Psychology
Biological Psychology
9008
Summer 2001
HIGHER STILL
Psychology
Biological Psychology
Advanced Higher
Support Materials
*+,-./
CONTENTS
Introduction
Statement of standards
Guidelines for teachers
Approaches to teaching and learning
Learning environment
How to use this pack
Recording student attainment
Student information and activities
Outcomes 1 and 2 - Key Concepts and Theories
Outcome 3 - Issues
Psychology: Biological Psychology (AH)
Psychology: Biological Psychology (AH)
SECTION 1: GENERAL INFORMATION
UNIT
Biological Psychology (Advanced Higher)
NUMBER
D402 13
COURSE
Psychology (Advanced Higher)
Acceptable performance in this unit will be the satisfactory achievement of the
standards set out in this part of the unit specification. All sections of the statement of
standards are mandatory and cannot be altered without reference to the Scottish
Qualifications Authority.
OUTCOME 1
Analyse major theories in biological psychology.
Performance Criteria
(a) Competing theoretical explanations in biological psychology are explained
accurately and comprehensively.
(b) Competing theoretical explanations in biological psychology are compared
accurately in terms of their main features.
(c) Competing theoretical explanations in biological psychology are contrasted
accurately in terms of their main features.
Evidence requirements
To demonstrate accurately attainment of this outcome, candidates should produce
written or oral responses to cover all performance criteria. They are required to do so
for two theoretical explanations chosen from the following:
• neural and hormonal systems and behaviour
• cortical functions
• awareness
• motivation
• emotion and stress.
Written/oral responses will typically be extended responses of between 1000 and
1500 words for each theoretical explanation and associated research evidence,
integrating Outcomes 1 and 2.
OUTCOME 2
Evaluate research evidence relating to theories in biological psychology.
Performance Criteria
(a) Research evidence relating to theories in biological psychology is described
accurately.
(b) Research evidence relating to theories in biological psychology is explained
clearly and accurately in terms of its strength and support for the theories.
Psychology: Biological Psychology (AH)
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(c) Validity of conclusions based on this research evidence is explained clearly and
accurately.
Evidence requirements
To demonstrate satisfactory attainment of this outcome, candidates should produce
written or oral responses to cover all performance criteria. They are required to do so
for research evidence in two areas chosen from the following:
• neural and hormonal systems and behaviour
• cortical functions
• awareness
• motivation
• emotion and stress.
Written/oral responses will typically be extended responses of between 1000 and
1500 words for each theoretical explanation and associated research evidence,
integrating Outcomes 1 and 2.
OUTCOME 3
Analyse an issue in biological psychology.
Performance criteria
(a) An issue relevant to biological psychology is explained clearly and accurately.
(b) Essential arguments of this issue are explained accurately and comprehensively in
a balanced way.
(c) The contribution of this issue to biological psychology is explained accurately
and comprehensively.
Evidence requirements
To demonstrate satisfactory attainment of this outcome, candidates should produce
written or oral response to cover all performance criteria. They are required to do so
for one issue from the following:
• psychology as science
• the use of non-human animals in research
• hereditary and environment
• biological determinism
• mind/brain relationships.
Written/oral responses will typically be an extended response of between 1000 and
1500 words.
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SECTION 2: GUIDANCE FOR TEACHERS
Approaches to teaching and learning
In delivering this unit, it is useful if teachers/lecturers achieve a balance between
teacher/lecturer exposition and experiential learning. It is important to recognise that
learners acquire and process information in a number of ways to help them learn.
These include visually, orally, in discussion or exchange with others, during
group-based problem solving activities, and during solitary reflection.
Students should be encouraged from the beginning to draw on their own experiences,
perceptions, and their previous and current learning. Personal experience of
interacting with a variety of people, and in a number of different situations is an
invaluable source of knowledge and is highly relevant to Biological psychology. The
sharing of experiences and insights will promote general awareness that Biological
psychology assists self-understanding and an understanding of humans in a variety of
contexts.
Students should also be encouraged to gather and use information about different
people’s actions, thoughts and feelings and to consider how these affect themselves
and others. Relevant quality newspapers and/or magazine articles and video/film
productions are useful resources, which bring Biological psychology to life so that it
can be shared, by comparatively large groups of people at any one time. This remains
appropriate even when the material is fictional, provided it presents us with a true
picture of the human condition, which is not deliberately sensationalised.
In delivering this unit it is appropriate that a multicultural approach is taken since the
learning needs of individuals vary according to their cultural background. Case
studies, role-play and simulations should incorporate characters and elements from
different social and cultural backgrounds wherever possible.
Unit induction
At the beginning of the unit ‘Biological Psychology’, teachers and lecturers should
ensure that Students are clear about its nature and purpose. Induction for this unit
should last about two hours and should include an introduction to the content of the
unit, provide a programme of work and explain the arrangements for assessment and
reassessment. At this point Students can be given the Candidates Guide from the Unit
Assessment Pack. This helps explain what the unit is about and how it is assessed.
In order to allow Students to make a confident start, reference should be made to links
with previous or other current learning with which they are familiar. It is also
important to discuss and explore the nature of the course or Group Award being
undertaken by the group if appropriate.
It may be necessary to include induction exercises, particularly if the group is a new
one. The type and number of exercises used will however depend on the nature of the
particular group, their familiarity with each other and with the teacher/lecturer
concerned.
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Learning Environment
The expertise of the teacher/lecturer is invaluable in developing skills in, approaches
to, and insights about the subject of Biological psychology. Teachers/lecturers should
aim to create a relaxed and enjoyable learning environment, which is both motivating
and supportive.
In order that a people’ perspective is always present the following conditions should
be met:
• the provision of a learning climate in which students feel supported and able to
express their thoughts and ideas.
• a teaching style that promotes a supportive learning climate.
• teaching and learning methods which draw on students’ past and present learning
experience and which enable them to integrate new ideas and skills during their
interactions with others.
Further guidance can be found in the Psychology Subject Guide.
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HOW TO USE THIS PACK
Purpose of the pack
This pack is designed to provide guidance and support materials to help
teachers/lecturers in the delivery of the unit. The student information and activities are
designed to be used by teachers/lecturers in the way that suits their preferred style of
delivery and the needs of their particular student group.
This pack has not been designed for open learning purposes. Additional reading,
exercises, assignments etc. and answers to enclosed exercises and worksheets will be
provided and facilitated by the teacher/lecturer. The student activities in the pack will
require to be followed up and brought together by the teacher/lecturer in whatever
way is most appropriate.
The student activities in this pack cover the three outcomes and their performance
criteria at Advanced Higher level. The Unit in the teaching/learning situation calls for
two key concepts, their features and explanations and one issue to be covered. This
Teachers Support Pack will endeavour to cover three key concepts, their features and
explanations and two issues.
This sequence of delivery is by no means compulsory and may be rearranged at the
discretion of the teacher/lecturer responsible for delivering the unit.
Using the materials
The student activity and information materials in the pack include both Information
and Student Activities.
These support materials should be used as the focus of input by the teacher/lecturer
and to develop ideas further as part of question and answer sessions and group
discussions.
These information sheets can be photocopied, as a separate pack should the
teacher/lecturer prefer to use them either as teaching notes or as separate handout
materials. Alternatively, the materials could be assembled into smaller topic packs.
These general activities have been developed to include exercises for individuals,
pairs, triads and small groups to conduct. Teachers/lecturers may well wish to alter the
way in which these activities are carried out according to the needs of their particular
group.
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RECORDING STUDENT ATTAINMENT
A recording proforma for teachers/lecturers to complete for individual candidate
attainment is available in the Unit Assessment pack.
•
•
Candidate’s record of progress - for individual candidates to have a record of
their attainment.
Internal Assessment Record - to record their internal assessment results of the
whole student group.
Teachers/lecturers may devise their own alternative system for recording student
attainment.
GUIDANCE ON THE CONTENT AND CONTEXT FOR THIS UNIT
By introducing students to a range of concepts; and associated theories, research
evidence and issues in Biological psychology, it is intended to develop knowledge
and understanding of Biological Psychology generally and to emphasise the
significance of this area to the whole of Psychology.
A choice of concepts and issues is a feature of this unit. This provides flexibility for
centres to accommodate different needs and interests in studying Biological
psychology at this level.
Fuller information on the content of this unit is provided in the course details.
GUIDANCE ON LEARNING AND TEACHING APPROACHES FOR THIS
UNIT
General proposals regarding approaches to learning and teaching are contained in the
course details. Learning and teaching approaches should be carefully selected to
support the development of knowledge and understanding, investigation and
application. The learning experience at this level should be interesting, to encourage
enthusiasm for the subject and to stimulate and prepare candidates for independent
study.
The unit should be approached using a wide range of stimulus materials and teaching
approaches. Candidates should be encouraged to draw upon their own experiences
and should have access to resources. The material should be up-to-date and relevant to
the unit, the level of study and the interests of the candidates. The emphasis
throughout should be on active learning, whether as part of a whole class, in small
groups or as individuals. The outcomes are interconnected and should be approached
as such. Especially so at Advanced Higher it is recommended that, wherever
possible, outcomes should be covered in an integrated way. An outcome-by-outcome
internal assessment approach, which could lead to a compartmentalized view of
psychology, should be avoided.
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GUIDANCE ON APPROACHES TO ASSESSMENT FOR THIS UNIT
The National Assessment Bank will provide assessment instruments and guidance on
implementation. This does not preclude teachers/lecturers from devising their own
assessment tasks. Evidence of attainment of the outcomes for this unit may be
provided through a variety of methods. Where an integrated approach is used for
assessment, it will be necessary to identify in the candidate’s response where each
outcome has been met.
Where assessment evidence is gathered by means of a single assessment towards the
end of the unit, care should be taken to ensure that sufficient time is allowed for
remediation and reassessment if required. Where a candidate has failed to achieve one
or more of the outcomes, it is only necessary to reassess those outcomes that the
candidate has failed to achieve.
Where assessments are set which allow candidates to demonstrate performance
beyond the minimum standard required, evidence gathered for internal unit
assessment might also be used for grade prediction and for appeals for external course
assessment. For details of the grade descriptions for external assessment, please refer
to the Advanced Higher Psychology course specification.
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SECTION 3: STUDENT INFORMATION AND ACTIVITIES
THE STUDY OF BIOLOGICAL PSYCHOLOGY
Psychology is the name given to the science which seeks to provide explanations for
human behaviour and mental processes. Biological psychology, also known as
biopsychology, behavioural neuroscience or behavioural biology is the scientific
study of the biology of the brain and behaviour (Dewsbury 1991). The main
assumption of this discipline is that biological mechanisms underlie all behaviour.
Many psychology students when embarking on a course in biological psychology
question the relevance of such a ‘scientific’ topic. However, if we are to understand
the complex interaction between brain and behaviour, mind and body it is necessary
that we have a basic understanding of the cells and organs of the body and the
physical and chemical changes which help determine and influence our behaviour and
mental processes.
Biological psychology does not provide us with all the answers regarding human
behaviour but it plays an important part. Areas of research in this area include:
• the interaction between brain and behaviour
• the influence of hormones on growth and development
• the manner in which psychoactive substances affect cognitions and behaviour
• the role played by genetics and environment in influencing behaviour
(traditionally known as the nature-nurture debate).
Biological psychology also concerns itself with evolutionary psychology or ethology,
the study of instinctive behaviours and reflexes, such as the predisposition for
aggression, or nurturing. In more recent times biological psychology has also been
concerned with genetic research - looking for a genetic basis for certain illnesses,
e.g. cystic fibrosis, schizophrenia or behaviours such as alcoholism/drug addiction or
crime.
Biological psychology is closely related to many other disciplines such as Biological
psychology, health psychology, and psycho-pharmacology to name but a few. It is
also a branch of neuroscience (the study of the nervous system), which itself
combines elements of a number of subdivisions such as neuroanatomy,
neurochemistry and neurophysiology.
Biological psychology has close links with evolutionary history and psychology.
The theory of evolution was proposed by Charles Darwin who stated that the
strongest organisms with the best characteristics for survival reproduced more
successfully and thus passed their survival characteristics to the next generation. This
principle known as natural selection and it may apply to behavioural capacities, as
they are mediated by the physical body which has evolved.
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Biological psychology therefore concerns study of the following psychological
processes:
• certain key concepts in Biological Psychology
• Neural and hormonal systems and behaviour
• Cortical functions
• Awareness
• Motivation
• Emotion
• Stress.
This pack emphasises the three key concepts of neural and hormonal systems and
behaviour, motivation and stress. The issues included are the use of non Human
animals in Research and biological determinism.
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INTRODUCTION: OVERVIEW ON ‘BIOLOGICAL PSYCHOLOGY’
Biological psychology concerns the relationship between physiological processes and
behaviour. Physiological processes refer to the way that the brain and nervous system
are involved in behaviour and cognition. In this support pack, we will explore three
key concepts in biological psychology:
•
neural and hormonal systems and behaviour
•
motivation, and
•
stress.
These three concepts have been selected as they illustrate many of the physiological
processes connected to biological psychology such as genetics, the brain and nervous
system, hormones and changes in growth and development. This unit will also
investigate the role that physiology and biology play in everyday life. For example,
how adequate are homoeostatic motivation theories as an explanation for human
behaviour? In addition, complementary and opposing theories will be discussed.
The Philosophical and Psychological Roots of Biological Psychology
Psychology is a comparatively new discipline, dating only to the 19th Century and the
establishment of the first formal psychological laboratory at the University of Leipzig
by Willhelm Wundt. Therefore, biological psychology as a separate and distinct
discipline is comparatively young. However, the theory of ‘biology as destiny’ was
formulated many centuries ago.
Psychology has philosophical and scientific antecedents. Biological psychology is no
different.
Somewhat surprisingly the brain has not always been considered as the location of
mental activities. On the contrary Aristotle believed (rather romantically) that the
heart controlled mental activity. The Bible took a more earthy approach mentioning
the heart, stomach, liver and bowels, whilst omitting the brain. The Greek physician
Hippocrates did not moot the idea that the brain was involved in behaviour until
around 400 BC. In 1633 the philosopher Descartes proposed a theory which came to
be known as dualism. Humans according to Descartes possess a non-material soul
and a material body. Descartes believed that the mind and body were linked by the
pineal gland. Modern biological psychologists reject this notion.
It was not until the 20th Century that biological psychology was ‘born’. Prior to this
time scientists did not understand the manner in which the brain was related to the
mind and the body.
Scientific advances which resulted in the discovery of localisation of brain function
led the psychologist William James (1890) to conclude that humans could be best
understood by studying the nervous system.
The 20th century saw huge advances in biological psychology. Edward Thorndike
demonstrated how to measure learning and memory in animals. Ivan Pavlov and
B.F Skinner investigated the role of conditioned reflexes and reward systems in
behaviour and Tolman demonstrated the existence of cognitive mind maps.
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In recent years technological advances have greatly aided the study of biology
psychology.
CAT, PET AND MRI scanners have furthered our understanding of complex
physiological and neurological systems. Biological psychology is still coming into its
own and it is likely that the best is yet to come, and there is still some way to go
before we have achieved a full understanding of the relationship between brain and
behaviour.
Biological psychology emphasises the importance of physiological processes in
influencing human and animal behaviour.
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KEY CONCEPTS IN BIOLOGICAL PSYCHOLOGY: NEURAL AND
HORMONAL SYSTEMS AND BEHAVIOUR
We will consider the following in relation to the study of neural and hormonal systems
and behaviour:
• neurochemicals
• organisation and function of the endocrine system
• interaction of hormonal system and nervous system
• theories and research of hormonal influences on behaviour.
The most important part of the human body is undoubtedly the nervous system. All
human thought, behaviour, action and emotion are in some way controlled by this
system.
The nervous system is in effect a massive information processing system, capable of
input, processing and output. Input is received from the outside world by means of
sensory signals - taste, touch, sight, sound and smell. These details are processed,
and categorised. Finally, the brain acts on the information by activating the muscles
to take the appropriate action.
But just how is this achieved? And which parts of the nervous system are involved in
which actions?
The first thing to be aware of when studying biological psychology is that the
nervous system is actually comprised of two parts: the central nervous system and
the peripheral nervous system. Each part is responsible for different functions, and
working together, they mediate all bodily functions, thoughts, behaviours and
emotions. Problems in any one area impact on the organism as a whole and inhibit
optimum functioning.
Specific Functions of the Nervous System
The Central Nervous System (CNS) is the part of the nervous system which is
encased in bone, namely the brain and the nervous tissue within the spinal cord. All
information is sent to the central nervous system to be acted upon.
The Peripheral Nervous System contains all nervous tissue that lies outwith the
central nervous system. It contains two subsystems namely the somatic and
autonomic nervous systems.
The Somatic Nervous System acts as a two-way system carrying messages between
(a) the sense organs and the CNS and (b) the CNS and the muscles of the body.
Every movement made involves the somatic system.
The Autonomic Nervous System carries messages between the central nervous
system and the organs and glands of the body. This area of the nervous system
carries out actions which are largely outwith conscious control, that is independent or
autonomic. For example, when you turn over your exam paper and realise that you
have studied all the wrong subjects then it is the autonomic nervous system which is
responsible for making your heart beat just that little bit faster.
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To further complicate matters the autonomic nervous system is divided into two
parts - the sympathetic nervous system and the parasympathetic nervous system.
The sympathetic system is involved in mobilising the body for action in times of
stress, usually known as the fight or flight syndrome. The parasympathetic system
is responsible for the regulation of bodily functions to conserve energy. The
sympathetic and parasympathetic systems work together to provide the appropriate
response at the appropriate time. The sympathetic and parasympathetic systems are
closely linked to the endocrine system.
Diagram of Nervous System
How do these systems communicate with one another?
In order to understand biological psychology it is necessary to understand a little
about the mechanisms of the nervous system. For those of you who do not have a
biology background this may appear a little tricky. However it is not as difficult as it
sounds. Basically the nervous system is something like a vast computer system. Each
area performs specific functions. If any area fails to function properly, it affects the
organism as a whole. For example, the speed that a message is transmitted down an
axon is dependent on whether the axon is covered with a myelin sheath or not. The
sheath is made up of specialised glial cells. A condition known as multiple sclerosis
(characterised by severe sensory and motor dysfunction), is a disease in which the
body destroys its own myelin. Multiple sclerosis effects the cognitive, behavioural,
emotional, psychological and physiological functioning of the individual.
Perhaps the best way to approach this topic is to look at the similarities between the
nervous system and that basic building block of life the cell. The nervous system like
every other part of the body contains cells.
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Similarities between cells of the Central Nervous System and other body cells
1. Both have semi-permeable outer membranes.
2. Both have a nucleus - which contains relevant genetic information.
3. Both contain a structure known as mitochondria which transforms glucose
and oxygen into energy.
There are two major types of cell in the nervous system: the neuron, and the glial.
Each performs a specific function. The neuron transmits, receives and responds to
signals. The glial aids the growth of the neuron, maintains the necessary chemical
environment, repairs damage to the cell, helps bind neurons together and sends
messages between neurons. In effect, the neuron is the racing driver and the glial the
motor mechanic.
Structure of the Neuron
There are approximately 12 billion neurons within the nervous system, the majority
of which are located in an area of the brain known as the cerebral cortex. They come
in all different shapes and sizes. There are three types of neuron:
• the sensory (or afferent) which relays information from the sense organs to the
central nervous system
• the motor (or efferent) which carry information from the central nervous system
to the muscles and glands and interneurons (found only in the brain, eyes and
spinal cord) which receive signals from sensory neurons and send impulses to
motor neurons
• other interneurons.
All neurons have long thin fibres which extend outward from the cell body. These
fibres are known as either axons or dendrites. Each cell has only one axon, which
itself may have many branches. The axon is responsible for carrying electrochemical
signals away from the cell body. This electrochemical signal is known as the action
potential. Hundreds perhaps thousands of elongated axons joined together are known
as nerves.
Each neuron can have many dendrites which themselves can have many branches.
Dendrites act as a detector for signals coming from axons and other cell bodies and
their role is to carry electrochemical signals to the neuron.
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Diagram of Neuron
In order for an electrochemical signal to travel down the axon, it is necessary to
instigate changes within the neuron. In its resting state the neuron is electrically
negative relative to the outside. Positively charged sodium ions cannot enter it.
When an electrochemical impulse (action potential) occurs, the inside of the neuron
momentarily changes from positive to negative, the sodium channels are opened and
sodium ions flood in. This sets off a chain reaction, sodium channels open at adjacent
membrane sites all the way down the axon.
The temporary change in the potential of the axon is known as the action potential.
The neuron is now said to have fired. Firing is something of an all or nothing affair.
Cells either fire at full strength or not at all. For many years scientists believed that
axons alone were capable of generating action potentials. However, recent research
indicates that an action potential may begin in either the axon or dendrites.
Action potentials which begin in the axon have the potential to go backwards (through
the cell body and into the dendrites) or forwards (down the axon). In addition, it
appears that action potentials, which spread from the cell body to the dendrites, enter
only certain specific branches, possibly indicating that these messages are involved in
strengthening connections between neurons.
There is also a great variation in the speed of an action potential (ranging from 0.2
metres per second to approximately 120 metres per second). The speed of an action
potential is dependant on two factors:
1. the presence of myelin
2. the diameter of the axon.
Communication is fastest when it is transmitted via large, myelinated cells. These
cells are most likely to be found in areas of the nervous system which carry the most
urgently needed information. For example, sensory neurons which receive
information via the environment are fast-acting myelinated cells.
Although neurons fire in an all or nothing manner, they do have the ability to vary
their rate of firing. For example, a neuron can fire repeatedly during the time that the
sodium gates open. However, between each firing there will be a brief rest period,
known as a refractory period. During these rest periods the gates for potassium
open, temporarily re-polarizing the membrane.
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When this happens the neuron can fire again. Current estimates indicate that a
neuron can send action potentials via the axon at a rate of 1,000 per second.
Neurotransmitters
However, communication between neurons cannot be achieved by means of
electrochemical signals alone, for two good reasons. Firstly, neighbouring neurons
are separated by minute synapses or gaps. Secondly, certain substances necessary for
communication (for example calcium and sodium) cannot enter the semi-permeable
cell membrane without some help. In order for a neuron to communicate effectively
with other neurons, it has to find a way to overcome these two problems. This is
achieved by means of chemicals known as neurotransmitters which are stored in
little pockets (known as vesicles) at the tips of axons.
Once an electrochemical signal has travelled down the axon, and arrived at the
terminal button, it stimulates the vesicles to discharge neurotransmitters into the
synapse between the terminal button and the dendrite of the receiving neuron. The
neurotransmitter then spreads to reach the next cell (also known as the postsynaptic
cell). Once the neurotransmitter reaches the postsynaptic cell it binds to proteins
known as receptors. Although each neurotransmitter ‘fits’ or ‘binds’ only with
certain specific receptors, and each receptor recognises only one type of
neurotransmitter, each neurotransmitter ‘type’ can bind together to a number of
different receptor types. Therefore, the same neurotransmitter can be involved in
several different affects depending on the type of receptor to which it binds.
Hundreds of new neurotransmitters are discovered every year, and each
neurotransmitter can be:
(a) excitatory
(b) inhibitory, or
(c) act to modify the receiving cell.
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Classification of neurotransmitters
1. Amino acid transmitters - glutamate, aspartate, glycine Gamma-aminobutryic acid
(GABA)
2. Monoamine transmitters - noradrenaline, adreanline, dopamine and serotonin
3. Acetylcholine
4. Neuropeptides.
To recap, a neuron receives and transmits messages to neighbouring neurons by
means of axons and dendrites. In its resting state the neuron cannot transmit
messages. Therefore, changes to the environment have to take place. When an axon
fires an electrochemical signal it temporarily changes the inside of the neuron from
positive to negative, allowing sodium ions to rush in and causing adjacent sodium
sites to open all along the membrane. The action potential shoots down to the end of
the axon until it reaches the terminal button and causes the vesicles to release their
neurotransmitters which then relay the message to neighbouring neurons. The
channels which have opened up to allow sodium ions in then close releasing
potassium ions out into the area surrounding the neuron and allowing it to return to its
resting potential.
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THE ENDOCRINE SYSTEM
Communication between neurons is therefore achieved by means of electrochemicals
and neurotransmitters. However, neurons are not the only cells, which use
neurotransmitters to communicate with one another. Cells in the endocrine system
(closely linked to the autonomic system) also make use of neurotransmitters.
Though not quite as glamorous as the central and peripheral nervous system and
certainly less sophisticated, the endocrine system plays a vital role in human
behaviour.
The endocrine system is responsible for a number of functions such as response to
stress and physical growth. Communication between the cells of the endocrine
system is achieved by secretion of chemicals known as hormones into the
bloodstream. Hormones are rightly and wrongly blamed for many things, in
everyday life. However, it is not true that only women possess hormones which cause
them to nag, cry and generally act irrationally! In truth men and women possess the
same hormones they merely have different amounts of each. For example, the
‘average male’ has higher levels of the hormone testosterone than the ‘average
female’. The ‘average female’ tends to have lower levels of serotonin than the
‘average male’.
Organisation and Function of the Endocrine System
The endocrine system is the simplest form of communication system of the human
organism. In effect the nervous system is the high flyer, the central nervous system
the managing director and the endocrine system a lowly office junior. But like the
office junior it does an awful lot of vital work. Hormones play an important role in
determining metabolic processes, growth, sexual orientation, aggression, emotion and
motivation. Hormones are secreted by the endocrine glands directly into the
bloodstream. Some endocrine glands are activated by the nervous system; others are
activated by changes in the internal chemical state of the body. There are three
specific types of hormonal communication:
• Autocrine communication releases a hormone which acts on the cell releasing
it
• Paracrine communication diffuses chemicals to neighbouring cells, and
• Endocrine communication occurs when the hormone is taken up by selected
target organs.
Hormones can only affect cells with receptors which recognise that particular
hormone.
Unlike neural communication, hormonal communication is comparatively slow and
longer-lasting in its effects. Hormones are produced in short bursts and they are
influenced by biological and environmental factors. Each has different effects on
different tissues, organs and behaviours.
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Major Endocrine Glands and their Role
•
Hypothalamus
controls the pituitary gland.
•
Pituitary Gland
regulates growth, and controls the thyroid, reproductive,
pancreas and adrenal cortex glands. Regulates water and salt
mechanism.
•
Thyroid
controls the metabolic rate
•
Pancreas
regulates sugar mechanism and controls glucagen and insulin
rates.
•
Testes/ovaries
affects physical development, reproductive organs and sexual
behaviour.
•
Adrenal Medulla
prepares the body for action - secretes adrenaline and
noradrenaline.
•
Adrenal Cortex
regulates carbohydrates and salt metabolism. Releases
corticosteroids involved in resistance to stress.
Some Major Glands of the Endocrine System
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Differences between Neural and Hormonal Communication
1. Neural communication involves rapid electrochemical messages between specific
anatomical connections. Hormonal communication is slower and the messages are
sent throughout the body via the bloodstream.
2. Neural communication is more likely to be under the control of the organism than
hormonal communication.
Similarities between Neural and Hormonal Communication
1. Neurons and hormone glands both produce and store their chemicals for release at
the appropriate time.
2. Neurons are stimulated to produce an action potential/endocrine glands are
stimulated to secrete hormones into the bloodstream.
3. Some chemicals act as neurotransmitter and hormone.
4. Neurotransmitters react to receptor molecules on the postsynaptic membrane;
hormones react on the surface or inside of the target cell.
5. Certain hormones and neurons are capable of releasing more than one message.
Interaction between the Nervous System and Hormonal System
Hormonal communication occurs within the endocrine system. However, the
endocrine system is influenced by the hypothalamus. The brain in addition to being
a major target organ of the endocrine system is also responsible for the control of the
release of hormones, sometimes directly, sometimes indirectly. For example,
hormones are instrumental in the human fight-or-flight response. In this instance,
neurons in the hypothalamus respond to stress by secreting a substance called
corticotropin-release factor (CRF). The CRF stimulates the pituitary to release
adrenocorticotropic hormone (ACTH). ACTH travels through the bloodstream to
the adrenal glands and various other organs of the body, along the way some 30
other hormones, vital to ensure that the body responds to an emergency are released.
The adrenal gland working together with the sympathetic branch of the autonomic
nervous system releases adrenaline (epinephrine) which causes the blood vessels in
the stomach and intestine to contract and the heart to beat faster. At the same time the
adrenal gland releases noradrenaline (norepinephrine) which travels to the pituitary
gland and stimulates it to release a hormone which acts on the outside layer of the
adrenal gland. This second hormone stimulates the liver to increase blood sugar and
raise energy levels to prepare the body for fight or flight.
Communication between the neural and hormonal systems occurs in a cyclical
fashion. Neurons can stimulate the release of hormones and vice versa. Messages are
sent back and forth at a phenomenal rate. Working together these two communication
systems ensure that we are equipped to deal with any emergency.
Hormones however do not only prepare us to take emergency action. Hormones play
an important role throughout our lifespan. A brief overview of the main functions of
hormones follows.
Psychology: Biological Psychology (AH)
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Gonadal Hormones
Almost all reproductive behaviour is dependent on hormones. The gonadal hormones
androgen and estradiol released prenatally (about 12 weeks gestation) determine
whether the infant is male or female. Then prior to puberty the hypothalamus
stimulates the pituitary to increase the amount of growth hormone into the
bloodstream. Cells of almost all body tissue are duplicated. The pituitary gland
releases a hormone that stimulates the testes to secrete testosterone and the ovaries to
secrete oestrogen and progesterone, which facilitates the development of secondary
sex characteristics, menstruation and the bodily changes which occur during
pregnancy. In middle adulthood the production of the female sex hormone oestrogen
declines eventually triggering menopause.
Disorders associated with Sex Hormones
Androgenital Syndrome, a condition caused by an excess of testosterone during the
development of a female foetus. Androgenital syndrome results in biological females
whose external genitalia resemble that of a male.
Testosterone Insensitivity. This condition occurs when the foetus does not respond
to testosterone. Chromosomally an individual suffering from this condition is male
but their external appearance is that of a female.
Adrenal Hormones
The adrenal glands (located in the kidney area) play a vital role in neural functioning
and the ability to deal with stress. The adrenal gland comprises two parts - the outer
layer (cortex) and the inner core (medulla). The cortex is controlled by the pituitary,
and the medulla by the sympathetic nervous system. The cortex releases adrenal
steroids which aid the synthesis and storage of glucose in the blood enabling it to take
quick action. The medulla releases epinephrine and norepinephrine into the
bloodstream thus reinforcing, sustaining and supplementing energy release.
Disorders of the Adrenal Cortex/Medulla
A deficient adrenal cortex may result in Addisons disease. This disease generally
occurs in middle age and is more common in men than women. Symptoms include:
• lack of energy
• exhaustion
• apathy
• irritability, and
• lack of concentration.
As the disease progresses the sufferer may begin to experience hallucinations,
disorientation and delusions. If left untreated this condition can be fatal.
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A hyperactive adrenal cortex often manifests as Cushings disease (caused by an
excess of cortisol). Symptoms of this disorder include:
• obesity
• hypertension
• increased blood pressure
• anxiety
• depression
• fatigue
• memory and cognitive deficits.
This condition can be treated successfully.
Adrenal steroids are also thought to play a role in mental illness but the exact
mechanism is not as yet known.
Thyroid Gland
The thyroid gland is responsible for the production of thyroxine. Thyroxine is
released during periods of emotional excitement. It aids energy release, raises
alertness, heart rate and body temperature. It is also involved in the development of
the nervous system prenatally.
Disorders of the Thyroid
An overactive thyroid gland at or near the time of birth can result in severe mental and
physical retardation. This condition is known as cretinism, and sufferers are often
deaf-mute, have no secondary sex organs and exhibit severe mental impairment.
Fortunately this condition can be prevented by the administration of thyroxine, at or
near the time of birth.
Hormonal over-stimulation of the thyroid also causes Grave’s disease a condition
which causes rapid weight loss, anxiety, fatigue and irritability. A deficiency of the
thyroid causes myxoedema (mix-o-de-ma) which causes the sufferer to become
depressed and suffer a loss of appetite and energy.
Pituitary Gland
The posterior pituitary gland is directly controlled by the hypothalamus, and
produces antidiuretic and oxytocin hormones. Antidiuretic hormone controls
urination and the level of water in body cells. Oxytocin is involved in the birth
process, facilitating uterine contractions and milk production.
The anterior pituitary is influenced by other endocrine glands. It releases 6
hormones:
• the stress hormone (ACTH)
• thyrotrophic hormone
• gonadotrophic hormone
• somatotropic hormone
• lactogenic hormone, and
• melanophore hormone.
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Disorders of the Pituitary
A deficiency of antidiuretic hormone causes diabetes insipidus. Obviously any
problems with the endocrine system as a whole will have an effect on the release of
the named hormones above and the functioning of the organism as a whole.
Theories and Research of Hormonal Influences on Behaviour
Neural and hormonal communication systems play a vital role in human behaviour.
They help make us what we are. They determine our biological sex, our physical
growth and play a part in our mental and physical health. But is this the whole story?
Early theorists believed that ‘biology is destiny’ by this they meant that an
individual’s genetic inheritance, biological sex and hormonal make up determined
who they were. In short they believed there to be certain innate and therefore natural
differences between the genders. Contemporary textbooks often refer to this as the
‘mamawaw theory’ (‘men are men and women are women’). This is known as the
biological approach and it was very popular for a long time. But how valid is it? Let
us look at a few examples.
Aggression
As we said at the beginning, biological psychology has its basis in evolutionary
psychology and ethology. Therefore, animal behaviours are of great interest to
biological psychologists.
Evidence exists to support the idea of a biological basis for aggression in lower
species.
Experimental research undertaken by Smith, King & Hoebel (1970) showed that
stimulation of the hypothalamus in lab bred rats could cause the rat to kill a mouse
which shared their cage. The rats killed the mice in exactly the same way as a wild rat
would, despite never having seen this behaviour and showing no aggression to the
mice previously. This process was also turned on its head. The rats who had
spontaneously killed the mice after their hypothalamus had been tampered with were
then given an injection of a neurochemical blocker into the hypothalamus. They then
became (temporarily at least!) peaceful. This experiment indicates that aggressive
behaviour involves some innate reactions. In higher order animals, instinctive
patterns of aggression are influenced by the cortex rather than the hypothalamus and
aggressive behaviour is a result of biology and environment.
In humans a biological factor often linked to aggressive behaviour is the hormone
testosterone. Social aggression in most cultures is much more common in men than
women.
Genetic males are exposed to testosterone in the womb, which has led to the theory
that testosterone somehow masculinises their brain, and provides a blueprint for
aggressive behaviour to be reactivated at puberty when testosterone levels are high.
There is some support for this theory in animals. Mice who have been castrated when
young are not aggressive when adults, and adult mice if castrated cease to be
aggressive.
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However, research by Albert, Walsh & Jonik (1993) has shown that increased
testosterone levels at puberty have no impact on the behaviour of human males, and
that castration does not reduce aggressive behaviour.
A large scale study undertaken by Dabbs & Morris (1990) in which over 4000 male
veterans were tested for aggressiveness indicated that males who had the highest
levels of testosterone in their blood were the most likely to have a past history of
aggression. Studies by Archer (1991) have indicated that violent criminals have
higher levels of testosterone in their blood than non-violent criminals. However, it is
likely that it is aggressive encounters which increase testosterone levels and not the
other way round.
Other Possible Explanations
Biosocial Theory - states that behaviour is a product of biology and environment.
This theory highlights the fact that boys and girls are treated differently from birth and
that boys are encouraged to be unemotional, aggressive and competitive. Girls are
encouraged to be compliant, placid and nurturing. Assertive behaviour is encouraged
in boys. However, biosocial theory acknowledges that there are certain innate
biological differences between genders. For example, research by Moss (1967)
indicates that baby boys are generally more irritable than baby girls. It is likely that
these innate differences are instrumental in influencing parents and society, so that the
infants are then treated differently, thus resulting in greater differences in behaviour.
Biosocial theory is closely linked to social learning theory.
Social Learning Theory (SLT) - states that aggressive behaviour is a learned
response. It views aggression as one of several possible reactions to frustration.
Aggression is not a biological drive but a cognitive-emotive choice based on past
experience and the likely outcome of the behaviour. Notable psychologists in this
field include Bandura and Bronfrenbrenner. According to SLT individuals aggress
if this behaviour has a positive-incentive for them. For example, if a child’s
aggressive behaviour is rewarded by significant others it is likely that this behaviour
will be repeated. The reward acts as a positive reinforcement. Conversely, if acting
aggressively protects the child from a negative consequence then aggression has been
negatively reinforced. SLT maintains that we learn via observational learning, and
that individuals imitate or identify with appropriate others. If the ‘other’ is
aggressive then we are highly likely to adopt such behaviour.
Recent developments in the field of forensic (criminal and legal) psychology support
this theory. Carpenter (1990) has undertaken research regarding the increase in
aggression by females. She maintains that this is due to the fact that women are
choosing to identify with male rather than female role models; females increasingly
view aggression as a way to achieve goals and status. Durkin (1995) also found that
girls are often more aggressive than boys, particularly when indirect non-physical
aggression is being measured.
Psychology: Biological Psychology (AH)
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Sex and gender
The biological approach to sexual orientation states that the differences between men
and women are a result of:
1. genetic differences
2. hormonal differences, and
3. the process of sexual differentiation.
Again research with animals supports the concept of a biological base for sexual
orientation.
Experimental work with rats by Dorner (1968), has shown that if you remove a small
part of a newborn male rats brain it will then act as a female rat would. Research
undertaken by Imperato-Mcginley et al (1974) provides tacit support for the view
that biology determines human sexual orientation in humans. In this remarkable case
four children from the Batisto family spontaneously changed sex from female to male
when they hit puberty. In total, thirty seven children from the same village as this
family changed sex. All of the children had a common ancestor who is thought to
have passed on a mutant gene. Whilst in the womb these children developed
normally, their neural system was exposed to testosterone at around twelve weeks and
they ought to have been born boys. However, one vital component was missing. The
boys received testosterone but they did not receive the hormone dihydrotestosterone
(di-hi-dro-test-tost-er-own). Without this, their external genitalia could not develop.
When they hit puberty however the increased amount of testosterone secreted
produced enough dihydrotestosterone to change their external appearance. All of
the children involved have successfully adapted to their change of sex and have taken
on male roles, and have married women. However, it is important to note that the
individuals’ transition has been eased by the support they have received from their
family and community regarding their new male identity.
However, the cases of ‘Mrs Went’ and ‘Mr Blackwell’ refute the idea of biologically
based sexual orientation, (Goldwyn, 1979). Mrs Went suffered from a condition
known as testosterone insensitivity. In the womb she developed initially as a male,
and developed testes. The testes secreted their first hormone and the female genitalia
disappeared. However, when the testes produced testosterone the foetus did not
respond to it. Mrs Went has no womb cannot menstruate and therefore cannot bear
children. Chromosomally she is male, although her external appearance indicates that
she is female. She has chosen to live as a female.
‘Mr Blackwell’ was born a hermaphrodite (an individual born with both female and
male genitalia). At puberty he developed breasts, menstruated and ovulated.
Exploratory tests revealed that he possessed one active ovary and one active testicle.
Mr Blackwell expressed the wish to be male and had surgery to remove his female
parts. Mr Blackwell has chosen to live life as a man.
Further criticism of the biological basis of sexual orientation can be found in the case
of transsexuals (individuals who are born equipped with fully functioning male or
female genitalia, who are socialised in the appropriate role and who are biologically
capable of reproduction yet who believe themselves to have been born in the wrong
sex). Psychological tests have shown that male to female transsexuals are more like
biological females and female to male transsexuals are more like biological males.
Psychology: Biological Psychology (AH)
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However, it would be naive to assume that biology does not have some role to play
regarding sexual orientation. In 1974 Money wrote about a case known as The
Circumcision That Went Wrong. An accident during circumcision resulted in an
infant male losing his penis. Assuming that gender is primarily a social phenomenon,
Money advised the parents to raise the infant as a female. Money studied the child
throughout his early years and consistently reported that the infant had adjusted
successfully to his feminine role. However, recent reports and the comments of the
individual concerned indicate the opposite to be true. The child did not adjust
successfully to his female role in either childhood or adulthood and now chooses to
live as a male.
Other Possible Explanations
Psychoanalytic Theory - proposes that homosexual sexual orientation is caused by a
failure to successfully resolve the Oedipal Complex may result in male homosexuality
and an absent or distant father may result in lesbianism.
Social Learning Theory - sexual orientation is learned behaviour. Accordingly
homosexuality, bisexuality and transsexualism may arise due to an individual
imitating the behaviour they see in significant others.
Mental Illness
The biological approach to mental illness states that mental illness is caused by:
1. genetic predisposition
2. physiological malfunction
3. neurobiological malfunction.
This is known as the ‘medical model’ of mental disorder.
There is some support for this theory, particularly with regard to the condition known
as schizophrenia. Biological psychology states that schizophrenia is caused by an
excess of the neurotransmitter dopamine. Research indicates that schizophrenics do
indeed possess unusually high levels of dopamine (Iversen, 1979). Further support
for this theory centres on the fact that high doses of amphetamine (which increases the
activity of dopamine) seem to produce similar symptoms to that of schizophrenia.
There is also some evidence to support a genetic basis for schizophrenia. Studies by
Shields (1976, 1978) have shown that monozygotic twins (identical twins) have
higher concordance rates for schizophrenia than dyzygotic twins (non-identical
twins). Heston et al (1966) studied 47 adults who had been born to schizophrenic
mothers, and who were subsequently adopted and compared them with other adopted
individuals whose biological parent(s) did not have schizophrenia. Incidences of
schizophrenia were higher in the group whose biological parents had schizophrenia
than those who did not.
However biology alone cannot explain schizophrenia. Whilst there is some evidence
to support a biological or genetic basis to the condition, it has not been proven
conclusively that biology alone is responsible. If it were, then there would be a 100%
concordance rate for monozygotic twins. The highest concordance rate in studies into
this condition is 69% (Kallman, 1946).
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Other possible theories into Mental Illness
The Anti-Psychiatry Theory - this theory states that mental illness is a ‘social
construction’. People who are classified as mentally ill are merely individuals who
do not conform to societal norms and values. Advocates of this theory include
RD Laing and Thomas Szasz.
Social Learning/Behaviourist Theories - assume that all abnormal behaviour
(including mental illness) is a result of maladaptive learned behaviour.
Summary
Our nervous systems and endocrine systems work in conjunction prenatally to define
our biological make-up. They continue to work throughout our lives, instigating and
monitoring our response to our environment, and ensuring the optimum functioning of
the organism. Communication takes place by means of neurotransmitters, and
electrochemical signals. Some chemicals act as both neurotransmitter and hormone.
Hormonal communication is generally slower and longer lasting than neural
communication. Disorders of the endocrine or neural system can have an impact on
the functioning of the organism as a whole.
Animal experiments tend to support earlier ethological and sociobiological theories.
In the lower animals behaviour does appear to be biologically determined to a very
great extent. However higher order primates and humans do not appear to be quite so
biologically determined. Our nervous system responds to the information received
from internal and external sources. How we perceive any given situation is a result
of, biology, individual personality traits, and the socialisation process.
In conclusion, biology does definitely have a role to play in influencing and mediating
human behaviour, but it does not act in isolation.
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QUICK QUIZ
1.
The endocrine system is closely related to the ........................... system.
2.
Communication between the cells of the endocrine system is achieved by
chemicals known as .............................
3.
Hormones are entirely responsible for the differences in behaviour exhibited
by men and women. True/False?
4.
Hormones are secreted by ............... glands and ................. glands.
5.
Some chemicals act as neurotransmitters and hormones. True/False?
6.
The central nervous system is the part of the nervous system encased in
...........
7.
The two subsystems of the peripheral nervous system are known as the
................. and ........................... nervous system.
8.
The autonomic system carries messages between the ................... and the
............ and ............. of the body.
9.
The sympathetic nervous system is involved in mobilising the body for
action in times of stress. This is known as the fight or flight response.
True/False?
10.
The parasympathetic system is responsible for the regulation of bodily
functions to conserve energy. True/False?
11.
Neurons ................ ..................... and ...................... to signals.
12.
Glial cells ..........................................................................................................
13.
Each cell has many axons. True/False?
14.
Dendrites carry signals to the neuron. True/False?
15.
Axons carry signals away from the neuron. True/False?
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GLOSSARY OF TERMS
Action Potential - the firing of a neuron.
Autonomic nervous system - the system which carries messages between the central
nervous system and glands and organs.
Axons - long thin fibres which extend from the cell body and carry messages away
from the neuron.
Biological Determinism - the theory that our biology determines our behaviour and
actions.
Central Nervous System - the part of the nervous system encased in bone, contains
the brain and spinal cord.
Dendrites - long thin fibres which extend from the cell body and carry signals to the
neuron.
Forensic Psychology - a branch of psychology concerned with legal and criminal
issues.
Glial cell - cell of the nervous system (but not a neuron)
Hormones - chemicals secreted into the bloodstream.
Neuron - cell of the nervous system
Neurotransmitters - chemicals which aid communication between neurons.
Parasympathetic Nervous System - responsible for the bodily functions which
conserve energy.
Peptides - short chains of amino acids, some of which function as neurotransmitters.
Peripheral Nervous System - contains all nervous tissue that lies outside the CNS.
Has two subsystems the somatic and autonomic nervous systems.
Resting Potential - the steady membrane potential of a neuron at rest.
Semi-permeable - allows only certain substances to pass through.
Somatic Nervous System - carries messages between the CNS and the muscles of the
body and between the sense organs and the CNS.
Sympathetic Nervous System - mobilises the body in times of stress.
Synapse - the space between neighbouring neurons
Vesicles - small pockets found at the tips of axons which store neurotransmitters.
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Psychology: Biological Psychology (AH)
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KEY CONCEPTS IN BIOLOGICAL PSYCHOLOGY: MOTIVATION
Motivation, a key concept in biological psychology can be roughly defined as a
factor(s) which influences the initiation, direction, intensity and persistence of
behaviour (Evans 1989).
We will consider the following in relation to the study of motivation.
• homoeostatic and non-homoeostatic motivation
• physiological factors in motivation
• theory and research of motivation.
MOTIVATION: INTRODUCTION
Psychologists describe motivation as the intervening variable (a factor which helps
explain the relationships) between environmental stimuli and behavioural
response. Different stimuli can provoke the same response and conversely the same
stimuli can provoke different responses in individuals. Clearly motivation is a
complex topic. We as individuals are all motivated to act in certain ways, seek certain
rewards, or deny ourselves certain pleasures. Below are some factors we must
consider in relation to the study of motivation.
1. Motivation cannot be directly observed it is a hypothetical construct.
2. Motivation can be intrinsic (internal) or extrinsic (external).
3. Motivation may be transient (short-term) or permanent (long-term).
4. Motivation can be:
• biological (the desire for food, water)
• emotional (fear, hate, love, envy)
• cognitive (arising from our perceptions and beliefs)
• social (arising from the influence of our social environment, our parents or our
friends).
5. Individual motivation arises due to a combination of:
• our personality
• our genetic and biological inheritance, and
• our social environment.
The sheer amount of motives for human behaviour is inestimable. Consider, for
example, the possible motivation behind embarking on this course in biological
psychology. Clearly the motivation will not be biological (advanced biological
psychology does not satisfy a desire for food and drink). For some, the motivation
behind your behaviour may be cognitive (you may want to learn more about
psychology) or it may be social (all your friends are doing it). It may be both. Some
may experience transient motivation (during or after this course your motivation
may wane). Others will be permanently motivated, that is they will continue to
study this topic long after school or college.
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What do you think the teacher’s motivation is? Or indeed mine as I sit here writing
this article at 11a.m. on a rainy Thursday morning? Perhaps it would be interesting to
record the details of the motivation for the entire class at the beginning of the course
and again at the end? Do you think there will be any changes in the motivation of
your classmates? Has doing this course had a positive or negative effect on you, and
what result has this had on your motivation and subsequent behaviour?
It is relatively easy to understand the motivation behind socially acceptable
behaviours but it is more problematic to understand the motivation behind those that
are socially unacceptable. What motivation can possibly lie behind an individual’s
desire to kill or maim, to indulge in dangerous practices (drug taking, drink-driving,
etc) or to continually take risks? Strange as it may seem, the motivational factors
behind pro-social and anti-social are similar. Factors of personality, genetic
make-up and socialisation influence the individual’s response to situations.
Within this module we will consider the psychological theories of motivation, and
the manner in which nature and nurture interact to influence human behaviour.
Theories of Motivation
As with all other areas of psychology, the study of motivation has its roots in
philosophy and biology. Within psychology there were two opposing viewpoints
regarding human behaviour. The Rationalists believed that all human behaviour was
the result of reason and logic and, therefore, did not really consider the concept of
motivation in any depth. Thomas Hobbes (17th century British philosopher) on the
other hand proposed the theory of hedonism. According to Hobbes all behaviour was
motivated by the pleasure principle (seeking pleasure and reducing pain). The most
influential scientific theory of human behaviour was undoubtedly Darwin’s theory of
evolution, and later psychological theories of motivation such as psychoanalytic
theory were strongly influenced by this.
There are four main psychological theories of motivation:
• instinct theory
• drive reduction theory
• arousal theory and incentive theory.
Instinct Theory
The earliest psychological theory of motivation is instinct theory. McDougall
(1908) proposed that all human behaviour could be explained in terms of instinctual
response. Instincts are automatic, involuntary and unlearned behaviour patterns
consistently ‘released’ by particular stimuli (Tinbergen, 1989). This strongly
nativist view (the belief that all species are born with certain innate faculties)
explained behaviour in terms of fixed action patterns (genetically coded responses to
particular stimuli). Therefore, instinct theory is a biological theory.
There is some support for instinct theory. Lower animals do respond in specific ways
to specific stimuli. A wild dog or wolf will kneel before the dominant dog of the pack
in submission in response to the bared teeth of the aggressor. Rabbits beat their feet
against the ground to signal danger. Human babies possess instinctive sucking,
smiling and grasping reflexes. We do not have to learn how to be hungry or thirsty or
tired.
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However, instinct theory provides only a partial explanation regarding human
behaviour. Many of the actions of humans cannot be explained satisfactorily by fixed
action pattern responses. For example, food is a basic biological need, we require it
for our survival. If we were ruled entirely by instinct then disorders such as anorexia
and bulimia nervosa would not exist.
Examples of instinct theory: Buss (1994a, 1994b) undertook a massive survey in
which 10,000 men and women from over 33 countries and 6 continents were asked
what their ideal partner was. Men generally preferred youth and good health (ideal
breeding capabilities) when choosing a prospective mate whilst females preferred
mature, wealthy males (to provide a stable environment for their offspring). Buss
concluded that this must mean that males and females are instinctively motivated to
choose a partner who will ensure the survival of their offspring and therefore their
genes. Dawkins (1973) ‘Selfish Gene’ theory suggests that humans have evolved so
that they are motivated to behave in ways that are likely to ensure survival of their
individual genes. Selection of a ‘suitable’ mate is one of a range of behaviours that,
Dawkins claims, have their origins in this evolutionary principle. However, these
views have been challenged, such behaviours can easily explained in terms of
social-psychological factors.
Drive Theories
Drive theories are so called because of the concept behind their inception. Whereas
instinct theory explains motivation in terms of instinctive responses to specific
stimuli, drive theories take a different view. According to drive theory the machine
(the human organism) is relatively passive and human behaviour can best be
explained in terms of the drive or power behind the behaviour. To put it more simply,
a human is very much like a car. A car cannot function properly without petrol.
Humans needs ingredients from the outside environment to ensure that they function
properly (food, water etc). Homoeostatic needs are identified in the brain, which
transforms them into psychological motives. There are two main forms of drive
theory. Homeostatic Drive Theory (Cannon, 1929) and Drive Reduction Theory
(Hull, 1943).
Homeostatic drive theory explains motivation in physiological terms and as such is
the only purely biological theory. According to homoeostatic drive theory an
organism is motivated to engage in behaviours which ensure the optimum functioning
of the organism. The human body needs a regular supply of raw materials from the
external world. We need oxygen to breathe and food and water to ensure that our
tissue needs are met. Breathing is an involuntary action. We do not need to engage in
any specific overt behaviours to maintain a supply of oxygen. Our core body
temperature is also maintained automatically. If we overheat, we perspire to bring our
body temperature down; if we are cold we shiver. However, if our internal
equilibrium is disturbed because we crave food or water, then we need to engage in
certain behaviours to obtain nourishment from the outside world. Homeostatic drive
is the internally driven process by which we seek to satisfy our biological desires.
Example of homoeostatic drive theory: Research by Blundell & Hill (1995) has
shown that a close relationship exists between how hungry an individual is and how
much they eat. This would seem to support the idea that we are ‘refuelling’.
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Drive Reduction Theory
According to drive reduction theory, imbalances in physiological functioning create a
biological need for a return to optimum functioning. The body may crave water but it
alone cannot take the appropriate action to get it. The brain then responds to these
Homeostatic needs by creating a psychological drive. A drive is a feeling of arousal
which motivates the body to take the appropriate action, which in turn reduces
homeostatic needs, returns the body to its optimum state. Once this has been
achieved the drive diminishes.
For example: Exercise → tissue needs not being met due to dehydration
→Homeostatic functioning impaired → brain creating a state of arousal which
prompts you to take the appropriate action → you get a drink →the need for fluid is
satisfied→ normal homoeostatic functioning resumed →desire for fluid diminishes
(i.e. the drive is reduced).
Unlike instinct theory and homoeostatic drive theory, drive reduction theory
acknowledges that motivation is influenced by learning. It makes a distinction
between primary drives (the biological need for food and water) and secondary
drives (money, a nice car, a good job, etc).
Primary drives are instinctive. We do not need to learn to crave food.
Secondary drives are artificial. We desire things that we are conditioned to desire.
For example, a good bottle of wine is no better than a glass of water for quenching
thirst, and it serves no specific biological function, (alcohol does not meet our tissue
needs). Yet some people will spend vast amounts of money to posses it because it is
seen as desirable. It may be that the merely like wine but in that case it would not be
so important to possess this particular bottle. The same can be said for money. It has
no intrinsic value, but in our culture it is highly prized. The motivation behind many
behaviours is financial, primarily because having money enables us to satisfy our
primary and secondary drives.
Although drive reduction theory can provide an explanation for a wider range of
behaviours than either homoeostatic drive theory or instinct theory it does not provide
an explanation for all behaviour. For example, it cannot explain why humans and
animals choose to indulge in behaviours which do the very opposite of reducing
drives. Skydiving, bungee jumping or absailing, do not reduce any particular drive on the contrary they increase arousal.
Arousal Theory
Arousal theory attempts to address the limitations of the other theories by proposing
that arousal levels dictate motivation. It works on the principle that each individual
has their own optimum level of arousal and will indulge in behaviours which enable
them to maintain this. In general we perform best when arousal is moderate. Over
arousal inhibits performance as does under arousal. For example, Marshall (1947)
discovered that in battle 75%-85% of soldiers become so over aroused they do not fire
their weapons properly (which is probably a distinct disadvantage)!
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Generally people engage in behaviours to increase arousal when it is too low and
decrease it when it is too high. However, this is not always the case. Some individuals
have a higher optimum level of arousal than others. These individuals are likely to
indulge frequently in behaviours which are stimulating and sometimes risky. Those
with a lower level optimum level of arousal are less likely to indulge in highly
stimulating pursuits. Arousal theory would explain someone who spends all their time
lounging about, reading or watching television as having a low optimum level of
arousal and someone who enjoys, dangerous sports, spicy food and loud music as
having a high optimum level of arousal. The most obvious flaw in this theory is that
arousal levels do not remain static and are subject to external as well as internal
factors. For example, someone who is lethargic may be ill, or depressed. Someone
who continually puts themselves in dangerous situations and appears to ‘live life to
the full’ may be seeking attention, trying to impress someone, or they may be
mentally ill (psychopathic, manic-depression). An explanation of these terms is
available in the glossary.
Another disadvantage is that an individual’s optimum level of arousal cannot be
measured merely inferred.
Incentive Theory
Incentive Theory differs from the other theories of motivation in that it explains
human behaviour in terms of a response to external rather than internal stimuli.
Accordingly, incentive theory states that people are motivated to behave in certain
ways in order to obtain positive rewards. Behaviours which do not get a positive
response are avoided. Individual differences in behaviour arise because of the
incentives available and the value the person places on them. For example, if a small
child is ignored by his parents and his good behaviour goes unnoticed, he may indulge
in anti-social behaviours (spitting, biting, tantrums) because this behaviour gets a
response. It does not matter to him that the response is negative (i.e. he gets punished)
because the attention he receives is preferable to being ignored. Incentive Theory
provides a partial explanation as to why people indulge in behaviour which has
detrimental consequences, for example drug taking. Many people experiment with
drugs. If an individual gets a positive response then he is likely to continue that
behaviour, even if the actual physical act of drug-taking is not enjoyable. A positive
response in this case could be the praise of the other drug-takers, the feeling of being
‘cool and rebellious’, the feeling of belonging, and a sense of self-identity. This was
the theory behind Zinberg (1984) drug-set-setting model of addictive behaviours.
For those of you who have encountered the behaviourist B.F Skinner you may have
noticed that this theory is similar to that of operant conditioning, whose key concept
is reinforcement. However, incentive theory places emphasis on cognitive factors.
The Humanistic Theory of Motivation
Maslow’s Hierarchy of Needs explains human motivation as a combination of
biological, psychological, security and aesthetic needs. Humans are not automatons;
they possess free will. Once an individual has satisfied basic biological needs, his
behaviour will be motivated by a desire to achieve self-actualisation. As each
individual’s self-actualisation is unique to them, it follows that each individual’s
behaviour and motivation will also be unique to them.
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Maslaw’s hierarchy is seen as a pyramid. At the wide base are physiological needs
(food, drink, oxygen, rest, sex, etc); immediately above are safety needs (protection
from dangerous objects, situations and threats); and the third layer consists of loving
and belongingness (need for trust, affection and to be part of a group). Above these
in order are esteem needs, cognitive needs, aesthetic needs with self actualization
(becoming everything one is capable of becoming) at the top of the ‘pyramid’.
To Recap :
There are four main theories of human motivation:
• Instinct Theory
• Drive Reduction Theory
• Arousal Theory
• Incentive Theory.
Instinct, drive and arousal theories explain motivation in terms of a response to
internal stimuli. Incentive theory sees motivation as a response to external stimuli.
The theory that adheres most closely to the biological perspective is homeostatic
drive theory which explains behaviour solely in terms of a response to the internal
needs of the body. We experience a need for water and food because our body
requires a certain amount of nourishment in order to be able to function appropriately.
Drive Reduction Theory and Incentive Theory accept the importance learning has
on human behaviour and go some way to explaining individual differences in
motivation. However, none of the above theories alone provides an adequate
explanation for human behaviour. It is likely that human behaviour is motivated by a
combination of instinct, drive, arousal and incentive. Maslow’s Hierarchy of
Needs (1954) provides perhaps the most comprehensive theory of motivation as it
encompasses facets of all of the above.
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Physiological Factors in Motivation
While we accept that the biological perspective on its own cannot provide a complete
explanation regarding motivation, it is true that physiological factors play a huge part.
A great deal of psychological research concerning biological psychology and
motivation has been undertaken concerning hunger, thirst, and addictive behaviours.
We will now look at the physiological factors which influence these behaviours.
Hunger
Food is a basic human requirement. We need to eat or we will die. Biological
psychology states that the drive for food is innate. But it is not as simple as that.
Sometimes, we eat when we know we are not hungry, at other times we deny
ourselves food when we wish to eat.
Physiological Factors Regarding Hunger
The physiological factors concerned with hunger and eating are extremely complex.
Neural and hormonal mechanisms interact to determine when we require nourishment,
when we are satiated (no longer hungry) and to a certain extent what we require to eat.
Evolution may have, to some extent equipped our brain with the ability to detect the
appropriate foods and to avoid those that are poisonous.
As we go about our lives we consume energy. Over time, our energy supply is
diminished to such an extent that we require nourishment from outside sources.
Neural and hormonal systems interact to monitor the availability of essential nutrients
in the bloodstream and to instigate psychological drives for replenishment. Once we
have eaten the digestive system proceeds to break down food into three specific types
of energy, lipids (fats), amino acids (derived from proteins) and glucose (a simple
sugar, which is a derivative of carbohydrates, and which is the main source of fuel
utilised by neuron cells in the brain). Although we continuously use energy, we
consume it only intermittently. Therefore, the body retains a store of energy (fats,
glycogen and protein) for use between meals.
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Links between the gastrointestinal tract and CNS
The Brain and Hunger
Early research (c.1940-1950) in biological psychology suggested that the
hypothalamus played an important role regarding hunger. Satiety (the feeling of
fullness) was thought to be under the control of the ventromedial hypothalamus, and
the lateral hypothalamus was thought to control eating. The brain monitors the
presence of essential nutrients in the bloodstream. In addition to glucose, it detects the
presence of the other main sources of fuel, fatty and amino acids. A decrease in the
amount of these nutrients may trigger the brain to send hunger signals to the stomach
in the form of stomach contractions (hunger pangs), which in turn instigate a
psychological drive to eat.
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In addition to monitoring the presence of nutrients the brain also monitors the
presence of the following hormones:
•
•
•
Cholecystokinin (CCK) - performs a dual function acting as a neurotransmitter
in the brain and a hormone in the gut.
Insulin- as glucose levels in the blood rise, insulin is sent to the pancreas to make
use of any excess and so keep glucose levels stable. Insulin is also thought to
increase the satiety response to CCK.
Leptin - manufactured by the fat cells leptin is responsible for providing the
sensation of satiety.
Hormones and Hunger
Pancreatic hormones play a vital role in instigating the chemical changes necessary to
make energy available to the organism. During the cephalic phase (the time when the
body prepares and the absorbative phase (the time when the body has stated to utilise
and store energy from a recent meal) the pancreas releases insulin and glucagon.
Insulin helps us ingest glucose and converts other blood borne fuels into units which
can be stored by the body. Glucagon aids the release of fatty acids (the bodies
primary fuel source). Ingested food interacts with receptors in the gastrointestinal
tract triggering the release of chemicals known as peptides, which provide the brain
with information regarding the type and quantity of food currently in storage.
The Gastrointestinal Tract And Hunger
In 1912 Cannon &Washburn undertook an experiment which involved Washburn
(the somewhat unfortunate student) swallowing an empty balloon which was attached
to a tube. The other end of the tube was attached to a water-filled U-shaped glass tube
to record changes in air pressure. Apparently, Washburn had no objection to this
request! The balloon was gradually filled with hot air. Stomach contractions were
measured by means of air expelled through the tube. Increases in the amount of air
produced a momentary increase in the level of water in the tube. Each stomach
contraction was accompanied by a ‘hunger pang’. This experiment led to the theory
that hunger can be described as the contractions caused by an empty stomach whilst
satiety is felt when the stomach is distended.
Physiological Factors Involved in Thirst
Although an organism requires relatively constant sources of nourishment to survive,
it is possible to exist for a relatively long time eating very little. An individual can
survive with no food at all for up to six weeks. However, we require liquid on a daily
basis, and it is unlikely that we would survive more than a few days without fluid.
Humans do not possess the capacity to store huge supplies of water and lose fluid
constantly via bodily processes (urination, defecation, perspiration, respiration and
evaporation).
The regulation of sodium and water in the body is controlled by the kidneys, which
take what the body needs and jettison the rest (in the usual manner). The body is able
to differentiate between two different types of ‘fluid shortfall’, cellular deprivation
(a reduction in intracellular fluid) and hypovolemia (hi-po-vo-le-me-ea) (a
reduction in blood volume).
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The physiological processes involved in thirst are much less complex than those
involved in hunger, however we drink when we are not really thirsty just as we eat
when we are not truly hungry.
Cellular Dehydration and Thirst
Cellular dehydration is usually the result of too much sodium chloride (salt) in the
blood, however it can also be caused by excessive alcohol or caffeine. Drinking,
smoking and snacking on crisps and peanuts may well help you stay awake while
studying long into the night for your biological psychology, but it will be hugely
detrimental to your intracellular structure, not to mention forcing your osmoreceptors
(cells that detect cellular dehydration) to work overtime. However, you will be glad
to know that excessive salt consumption has little effect on the volume of blood in
your body!
Research by Blass & Epstein (1971) has indicated that osmoreceptors are located in
the lateral preoptic area of the hypothalamus. Osmoreceptors can induce thirst
directly (via neural mechanisms) and indirectly (via hormonal mechanisms). A
reduction in blood volume (Hypovolemia) is detected by baroreceptors (blood
pressure receptors) and blood-flow receptors (which monitor blood flow). On
detecting a drop in blood flow, baroreceptors release antidiuretic hormone (adh)
which triggers changes in the kidneys causing them to:
1. conserve remaining water sources by reducing the amount of urine produced
2. trigger a desire to drink. Water deprivation triggers the hypothalamic
osmoreceptors and the heart baroreceptors to release antidiuretic hormone
from the posterior pituitary.
Other Substances Involved in Thirst and Drinking
• Renin - a hormone release by the kidneys which stimulates the production of
angiotensin 11.
• Angiotensin 11- a peptide hormone, which instigates a response in blood
pressure.
• Aldosterone - a hormone released by the adrenal cortex which causes the kidneys
to reabsorb sodium.
• Dispogen - a substance produced by the kidneys which is thought to induce
drinking.
Physiological Factors in Addictive Behaviours
Many us of indulge in behaviours which adversely affect our health, mental well
being and financial security. A great many individuals do manage to stop smoking,
drinking, gambling etc, once it has started to have an adverse effect on their lives.
However, some others cannot stop, they are ‘addicted’ to their drug of choice. An
individual is said to be addicted when they exhibit signs of physiological and/or
psychological substance dependence. Physiological dependence is evident when
cessation of the behaviour results in withdrawal symptoms (cramps, headaches,
hallucinations etc). There is some evidence to support the theory of a biological basis
of addiction.
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The motivation behind a great deal of human behaviour is pleasure. It follows that
pleasurable behaviour is likely to be repeated. There is a theory, that the brain itself
has the ability to recognise pleasure, and that all pleasurable activities activate a
specific brain reward system, known as the mesolimbic dopamine system. Messages
are transmitted by means of the neurotransmitter dopamine. The mesolimbic
dopamine system can be stimulated by good food, falling in love, an evening with
friends, anything that brings pleasure to the individual.
Three major factors combine to make certain psychoactive drugs a more powerful
incentive than other substances.
1. They possess the ability to overactive the brain systems of reward, because they
can act directly on brain neurons. They provide a ‘super-reward’ which increases
the motivation to repeat the behaviour.
2. If certain drugs are taken regularly the reward systems in the brain may become
harder to activate, which leads to increased consumption and tolerance.
3. Certain psychoactive drugs have the ability to induce permanent changes in the
brain reward system. Repeated use of cocaine and heroin may cause neurons to
become permanently sensitised. This may lead to exaggerated craving for the
substance or similar substances. In some instances, a drug user can experience
cravings for the substance merely by looking at pictures of drug paraphernalia
(syringes, silver foil, etc).
Now that we have mentioned some of the physiological factors involved in motivation
we shall evaluate research undertaken concerning the biological basis of motivation.
Research which supports the Biological Theory of Motivation regarding Hunger
We have already established that homoeostatic drive theory states that the
motivation to eat arises due to an external response to an internal stimulus - our
body requires fuel to replenish energy and our brain creates a drive to eat. Early
research in biological psychology assumed that our hunger was controlled by a system
known as set-point. Set-point theories assume that eating is merely the action
necessary to ensure that our energy levels return to normal. All set-point mechanisms
have three components:
• a set-point mechanism which defines our individuals set point
• a detector mechanism : which detects deviations from this set point, and finally
• an effector mechanism: which acts to eliminate the deviations.
All set point systems are negative feedback systems. In any negative feedback
system, changes to one component will start off compensatory chain reactions in the
other direction.
Early research in psychology undertaken in the 1940s and 1950s worked very much
on the assumption of set-point theories. Theorists at this time formulated two set point
theories to explain hunger. Glucostatic theory maintains that we become hungry
when our blood sugar levels drop below a certain point and lipostatic theory which
states that every individual has a set point for body fat and deviations from this point
motivate us to eat to redress the balance.
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However, set-point theories of hunger have some serious faults. Set-point theories
maintain that we are motivated to eat only when our body detects that our energy
supplies are in need of replenishment. However, if we stop feeling hungry as soon as
our bodies have taken in nourishment we would not be able to survive periods when
no food was available. Our eating system must be more sophisticated than set-point
theories allow for. Further evidence against this theory is evident when we consider
the research undertaken by Smith et al (1972). Smith and his colleagues discovered
that blood glucose levels are maintained at almost constant rates by pancreatic
hormones even while we are fasting. Premeal injections of glucose do not suppress
eating Rowlands (1981) Thirdly, set-point theories provide no plausible explanation
for over-eating or indeed under-eating, and do not explain why we tend to choose to
eat things that are sweet but have little nutritional value.
In addition, the physical act of eating a large quantity of food is actually quite
stressful in the short term to the body and probably does more to upset homeostatic
balance than mild hunger itself. Woods (1991) states that the hunger pangs we
experience at regular intervals are not caused by a decrease in energy but by the body
preparing itself for the homoeostatic dis-equilibrium which will occur once we have
eaten.
These criticisms led in time to a theory of eating known as positive-incentive theory,
which explains eating as a behaviour which has a positive-incentive value. In short
we eat when such a behaviour has a high value and we fast when there is no value
attached to this behaviour. Many external and internal factors help determine the
value we attach to eating at any specific time. For example, Redd & de Castro
(1992) discovered that the presence of others can motivate us to eat up 60% more than
we would if eating alone.
Rogers & Blundell (1980) discovered that rats ate more food if a varied diet was
presented to them than if they were merely presented with one or two choices. This
indicates that satiety (feeling full) may be dependent on the taste of the food rather
than any homeostatic drive. If however, that food was replaced with something else,
the chances are that we would start eating again. If we think about it, this theory has a
great deal of validity. We have all been out to parties where we have sat and stuffed
ourselves with peanuts and crisps, and after a while we do not want to eat them
anymore (the food now has low-incentive value for us). However, if the hostess came
round with a tray of mini-trifles the chances are we would all eat one (at least). We
are not hungry, we merely require a different taste.
Positive-incentive theory is also useful in explaining eating disorders such as
anorexia nervosa (a condition in which the sufferers deny themselves food to the
point of emaciation, starvation and in some instances death) and bulimia nervosa (a
condition characterised by starvation, binging and purging of food). In both these
conditions, the incentive to avoid weight gain is stronger than the incentive to eat.
Psychology: Biological Psychology (AH)
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Hypothalamic Mechanisms in Hunger and Satiety
In 1940 Hetherington & Ranson undertook experiments on rats which involved
cutting the ventromedial hypothalamus. This resulted in a condition known as
hyperphagia (hi-per-pha-gia) or excessive eating. Research by Anand & Brobeck
(1951) indicated that cutting the lateral hypothalamus in rats caused aphagia
(a-fay-gia) a complete lack of eating. It would seem therefore that the hypothalamus
does play a role in control of hunger and eating. Earlier theorists went as far as to say
that it was the brain’s feeding centre. This is no longer accepted but research has
shown that the lateral hypothalamus contains neurons which respond to the positive
incentive properties of food Rolls & Rolls (1982).
Gut Satiety Peptides
Leibowitz (1992) has shown that gut peptides play an important role in determining
satiety by binding to receptors in the brain and reducing food intake.
However, although physiological factors do play a role in the motivation to eat or not,
it is likely that environmental factors are of similar importance. Eating is in many
cases a social activity, which serves an important psychological as well as
physiological purpose. In the Western world we are lucky enough to have adequate
food. Most of us do not go hungry. In fact many of us overeat. Despite this many of
us suffer from poor nutrition. We only have to look at the high incidences of eating
disorders to understand that our culture plays a huge part in the way we value food. In
contemporary society we are faced with the social pressure to be thin. Many
vulnerable individuals deny themselves food, perhaps, because it has less value to
them than social acceptance or other goals. Homeostatic theories alone cannot provide
an adequate explanation as to the motivation behind hunger and eating.
Research into Thirst
Given that we cannot survive for very long without fluid, water deficits provide a
powerful motivation to drink. However, just as we eat when we do not require energy
we drink when we do not require fluid. This is known as spontaneous drinking. It is
likely that the motivation to drink in these instances arises from the positive incentive
that accompanies the action, (in most cases this will be the flavour of the drink).
Research by Rolls, Wood & Steven (1978) has shown that when rats are presented
with water with sugar added to it, they will drink significantly more than they will
when presented with plain water. Conversely, if you add quinine to the water the rats
will drink less of it (smart rats)! However, when rats were presented with quinine
flavoured water only for a long period of time, then they will drink it and indeed they
will drink more of it than they would if there were alternatives.
All species tend to drink more than they require, and will increase their fluid intake in
anticipation of deficits. For example, long distance runners ensure that they drink
before setting out on their run and rats tend to drink more when presented with a high
protein diet (Fitzsimmons & Le Magnen, 1969).
Given these factors it would seem that set point theories cannot be applied to drinking
any more than they can to eating.
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Research into Addictive Behaviours
This is a tricky subject primarily due to the fact that ingestion of psychotropic
substances does undoubtedly have an effect (often long-term) on the neurotransmitters
and receptors of the central nervous system. If an individual’s mesolimbic dopamine
system has been exposed to these substances, it is possible that they will have great
difficulty in ceasing these behaviours.
Therefore there may well be a physiological basis to addictive behaviours, just as it is
possible that some individuals may be genetically predisposed to substance abuse.
Research which supports the biological theory of addiction includes that of Koob et al
(1993) who discovered that addicts who have abstained from drugs and then return to
the ‘scene of the crime’ at a later date experience conditioned withdrawal effects
opposite to the effect of the drug. This, in turn, elicits a powerful craving for the drug.
However, biological psychology cannot explain why certain individuals manage to
overcome their addictive behaviours and some do not. Again we have to look to
cultural and social influences.
Addictive behaviours are probably best explained as a combination of biological and
environmental factors. For example, Robinson & Berridge (1993) suggest that
individuals who are prone to addiction may be more sensitive to the effects of positive
incentive. They believe that the drugs themselves cause this sensitisation in the brain.
Therefore, these individuals could be seen to be physiologically and socially
motivated to continue to take drugs.
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SUMMARY
Psychology has long battled to understand the factors that motivate human behaviour.
A number of theories have been proposed instinct theory, homoeostatic drive and
drive reduction theories, arousal theory and incentive theory. Maslow proposed
that human motivation could best be understood in terms of the need to self-actualise
(achieve their full potential). Homoeostatic drives and instincts do explain some basic
human behaviours. However even relatively simple actions such as eating and
drinking cannot be explained fully by strictly biological theories. Motivation can be
intrinsic, extrinsic, transient, permanent, biological, social, cognitive or
emotional. The motivation for a behaviour may wane over time particularly if the
behaviour has a low or negative incentive value. Conversely it may persist due to the
fact that the behaviour is perceived as having a positive or high incentive value for
the individual. Incentive values provide a partial explanation as to addictive or
obsessive behaviours.
Human behaviour and the motivation behind it is so complex that we cannot state
categorically that any one theory of motivation provides a complete explanation. We
are all at least partially motivated by our internal needs, and as a consequence we
cannot completely exclude homoeostatic and drive reduction theories. However,
environmental factors do play a huge role and it would be wise to remember that what
we do is motivated to a great extent by those around us.
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QUICK QUIZ
1.
Motivation is always permanent. True/False?
2.
Motivation is unique to each individual. True/False?
3.
Homoeostatic and drive reduction theories provide the only explanation for
activities such as eating and drinking. True/False?
4.
Arousal Theory states that we all have the same optimum level of arousal.
True/False?
5.
The ‘reward system’ in the brain is located in the mesolimbic dopamine
system. True/False?
6.
Individuals who are addicted to drugs have no dopamine in the brain.
True/False?
7.
Glucostatic theory and lipostatic theory are the only possible explanations for
hunger. True/False?
8.
The drug-set setting model maintains that drug addiction is biologically
determined. True/False?
9.
We can be conditioned to desire certain things. The drive behind this is
called a ................…..
10.
Leptin is manufactured by the .............. cells.
11.
A reduction in blood flow is known as ....................................
12.
The regulation of sodium and water in the body is controlled by the
...................
13.
The presence of others causes most individuals to eat ........................
14.
Anorexia is a condition where an individual alternatively starves and binges
on food. True/False?
15.
An individual is said to be addicted when they display ...................... and
.................. symptoms once they cease taking a certain substance.
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GLOSSARY
Absorbative Phase - the phase in which the body is using the energy from a recent
meal and storing the excess.
Amino Acids - the breakdown products of proteins.
Arousal Theory - a theory which states that every individual indulges in behaviours
which allow them to function at their optimum level of arousal.
Cephalic phase - the phase in which a body prepares for food that is about to be
absorbed
Dopamine - a neurotransmitter thought to be involved in addictive behaviours,
schizophrenia and Parkinsons disease.
Extrinsic - not innate, external.
Glucagon - pancreatic hormone which helps release of fatty acids.
Homeostasis - the stability of an organisms internal environment.
Insulin - pancreatic hormone which facilities the entry of glucose into the cells
Intrinsic - innate, something internal to the individual.
Manic Depression - also known as bi-polar or uni-polar disorder. A condition
marked by periods of extreme depression and mania.
Mesolimbic Dopamine Centre - an area of the brain often known as the
‘pleasure/reward’ centre.
Negative Feedback System - systems in which feedback from changes in one
direction cause changes in another direction.
Psychopathy - a severe personality disorder characterised by a number of
characteristics and behaviour including: lack of empathy, emotion, guilt or regard for
others. Psychopaths are often said to have no conscience.
Self -Actualisation - realisation of one’s full potential - a motivation thought to be
unique to humans.
Transient – temporary.
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Psychology: Biological Psychology (AH)
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KEY CONCEPT: STRESS
We will consider the following in relation to the study of stress:
• stressors
• models and research of stress
• individual differences involved in stress
• coping with stress.
Stress is a word which is part of everyday language. We all claim to be stressed at
least once a day (probably more) and we generally assume that stress in entirely
detrimental. It is often linked to negative emotions, thoughts and behaviour. We
rarely view stress in a positive light. However, stress is vital for our survival. It
provides us with the energy to meet the requirements of daily life, and to take action
in the face of potentially dangerous situations. Nevertheless stress can be
life-threatening and repeated long-term exposure to highly stressful situations can
have a detrimental effect on both physical and mental health. Environmental factors
which cause stress are known as stressors whilst the behaviours we exhibit and the
symptoms we experience are known as the stress response.
Stress is of immense interest to behavioural and health psychologists. Biological
theories of stress concentrate on the physiological and psychological reactions to
internal and external stressors. The concept of stress as a distinct physiological state
was formalised by the psychologist Walter Cannon in the early 20th century. The
Cannon-Bard Theory of Emotion (1932) states that the sympathetic branch of the
autonomic nervous system cannot distinguish between different types of emotional
stimuli . Therefore, it responds to all emotional stimuli in the same manner by
preparing the body for fight or flight. In physiological terms, the fight or flight
syndrome refers to a situation whereby the body is ‘turbo-charged’ for action. Heart
rate, respiration and blood pressure all increase, adrenaline and non-adrenaline are
released into the bloodstream. Fight or flight is vital for emergency situations
(coming face to face with an armed robber, being chased by an angry mob etc).
However, if stress is merely a physiological response to emotional stimuli, then we
must have some way of determining between positive and negative emotional stimuli
or we would live in a permanent state of physiological arousal. Individual
cognitions, personality and social factors help us determine what is stressful and what
is not.
In psychological terms, Stress is:
1) a process in which internal and external processes threaten an individual’s
well-being
2) a process which involves psychological, physiological, behavioural and
biochemical dimensions.
Groesch & Fuller (1995) define three categories of stress:
1) Stress as a stimulus - linked to the engineering model.
2) Stress as a response - linked to the physiological model
3) Stress as interaction between an organism and its environment - linked to the
transactional psychosocial model.
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Models and Research of Stress
The Engineering Model - this model views stress as something which happens to an
individual. External stressors arising from our environment (the car won’t start, the
bus is late, your cat dies) are all things that happen to you. Sometimes we can cope
with these stressful events - when we cannot we become stressed.
The Physiological Model - this model is concerned with what happens within the
person as a result of stress. Stress is defined as the ‘the non-specific response of the
body to any demands made on it’ (Selye, 1956). Selye noticed that some situations
seemed to elicit similar responses. For example, illness (regardless of type) tends to
be accompanied by loss of appetite, weight, strength and ambition. Selye believed that
these physiological symptoms were a result of the general adaptation syndrome, i.e.
the body’s adaptation to stress.
Three Stages of The General Adaptation Syndrome
Stage 1 - Alarm Reaction
This stage occurs when the body first becomes aware of a stressor and mobilises its
physiological defences. The sympathetic branch of the autonomic nervous system
stimulates the adrenal medulla to release the stress hormones (adrenaline and
noradrenaline).
Adrenaline and Noradrenaline are responsible for:
1) increasing heart rate, blood pressure, concentration and metabolism
2) releasing endorphins (the body’s natural painkiller) into the bloodstream
3) secreting carbohydrates into the bloodstream, which provide the energy for
emergency fuel consumption
4) temporarily shutting down the digestive tract to allows blood to be diverted to the
muscles.
Stage 2 – Resistance
If the stressor does not disappear then the body begins to recover from its initial alarm
response. Sympathetic activity decreases and the levels of adrenaline and
noradrenaline in the bloodstream is reduced. During this stage the hypothalamus
initiates activity within the endocrine system by:
1. secreting corticotropin releasing factor which stimulates the anterior pituitary
to release adrenocorticotropic hormone (ACTH)
2. adrenocorticotropic hormone provides the body with glucose energy and
stimulates the release of glucocorticoid hormone
3. glucocorticoid hormones provide the body with glucose and fats, increase blood
flow and stimulate the behavioural responses of the fight or flight syndrome.
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Stage 3 – Exhaustion
Once sufficient amounts of ACTH and glucocorticoid are released into the
bloodstream, the central nervous system shuts down the secretion of ACTH. This is
known as a negative feedback system. If the source of stress disappears at the
resistance stage, blood sugar levels will return to normal. However, if the stress
persists other parts of the brain override this negative feedback loop and instigate the
whole process again. Exhaustion occurs when the body’s resources become depleted
to the extent that they cannot function properly. In extreme cases this can lead to
death.
The Transactional Model (Lazarus, 1965), sometimes known as the psychosocial
model, combines elements of both the engineering and physiological model.
Accordingly stress is seen as arising from a combination of internal and external
factors. Stress is likely to result if there is an imbalance between the perceived
demands made on the individual and the individual’s perception as to how they will
cope.
Complex individual cognitive, emotional and physiological factors determine:
1) whether a situation is seen as positively stressful or negatively stressful ( for
example, falling in love is generally a positive thing, failing your driving test is
not)
2) whether the individual believes they can cope with the situation or not
3) the coping strategy adopted.
What Causes Stress?
Everyone differs in what they perceive as stressful. For example, I personally would
not find talking in public particularly stressful. On the other hand, if you asked me to
sit in the same room as a snake I would definitely experience the full range of fight or
flight responses (in fact if I am truthful I would probably faint)! Every individual
views situations differently and possesses different abilities to cope with them.
However, it is generally accepted that the following factors are likely to act as
stressors for the majority of individuals.
Frustration - Most individuals experience stress when they are frustrated in their
desire to do something. Failure to achieve your goals can be due to internal or
external factors. For example, you may wish to be a famous singer, but do not
possess the confidence (internal factor) to go for the audition, alternatively you may
possess the ambition, talent and drive but miss the audition because the bus was late
(external factor).
Conflict - this occurs when we experience a number of contradictory goals and
motives. There are three main types of conflict:
• Approach-Approach Conflict - this occurs when we have to choose between two
or more alternative course of action which are equally attractive. For example,
suppose you had been shopping and spotted and exceptionally nice pair of shoes
and a stunning coat which you just had to have. You can only afford one. What do
you do?
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•
Avoidance -Avoidance Conflict - this happens when you have to make a choice
between two equally unappealing choices. For example, you have an overdraft and
must decide whether to work long hours stacking supermarket shelves to pay it off
or get another nasty letter from the bank manager.
•
Approach-Avoidance Conflict - this happens when a situation has both desirable
and undesirable attributes. For example, say that like me you have a fear of snakes
and you have been offered a free holiday in Egypt (where you have always wanted
to go). Do you go keeping a wide eye out for slithery things or do you turn down
the holiday?
Disruption of Circadian Rhythms
Most life forms work best when they perform physiological and behavioural functions
in a rhythmic manner. These circadian rhythms are endogenous (internally
controlled). We can adapt to some changes relatively quickly, others take longer
(adrenal cortical hormone and core body temperature). Disruption of circadian
rhythms, particularly those relating to sleep and activity can have a hugely detrimental
affect on the body’s ability to cope. Whilst our bodies are acclimatising to new
conditions, we experience what is known as internal desynchronization Aschoff
(1979). This is very stressful and can result in a variety of physical symptoms.
Disruption of circadian rhythms is experienced on a regular basis by shift-workers and
those who cross time zones whilst travelling. Research by Blakemore (1988)
indicates that shift workers experience insomnia, depression, irritability, fatigue and
digestive problems. Individuals who change shifts on a weekly basis are involved in
more accidents than those who do not and have lower productivity.
Think back over the last few months. Write down something that has happened to
you. I can guarantee that all of you will have experienced some change in your lives.
It might be something as little as having your haircut or going on holiday, or it might
be something fairly major like moving house. Holmes & Rahe (1967) believed that
stress results from anything which causes us to change our behaviour. They created
the Social Readjustment Scale (SRRS) in order to test whether exposure to stress led
to illness. Participants were required to indicate which of the 43 items on the list they
had experienced in the last year. The score is tallied together and the higher the score
the greater likelihood of health problems. The SRRS is given on pages 64-65 of
Biological Psychology (Higher) support materials (HSDU, 2001).
Not surprisingly catastrophic life events top the SRRS. These events are potentially
life threatening and include, personal injury or illness, death of a loved one, and being
sent to jail.
The effects of any of the above tend to be long lasting and, prolonged stress during
this period, may lead to physical and mental exhaustion and post-traumatic stress
disorder.
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Further down the scale we find stressors including losing your job, getting a new job,
marriage, financial problems and moving house. These stressors are not
life-threatening on their own but they can lead to stress in other areas. For example,
losing your job can cause financial hardship, relationship difficulties and a change in
living conditions.
At the bottom of the scale we find things which involve relatively little change in your
daily routine, but which are irritating in the short term. These include things like,
Christmas, holidays and minor violations of the law.
A number of studies seem to show a correlation between life changes and illness. In
general individuals who score 300 or more on the Social Readjustment Scale appear
to be more susceptible to physical or mental illness. However, it is not possible to
ascertain categorically that exposure to significant life events causes the illness.
Indeed, certain stressful life events may themselves be early manifestations of a
developing illness. Another problem with these studies is that may of them are
retrospective (after the event) which often produces unreliable data.
The Social Readjustment Scale is rather old now and rather out of date. If you were
writing the SRRS now what stressors would you get rid of and which ones would you
add?
Environmental Stressors
These can be very stressful. Environmental stressors include overcrowding,
background noise, pollution, excessively bright or dim light. Many workers are
exposed daily to repeated stress, whether it be in the risk to their health (exposure to
pesticides, toxins and chemicals) or to their sanity (too much pressure, deadlines,
conflicting information, lack of control over work or poor social relationships with
colleagues). Home and family life can also be very stressful.
Research by Dennerstein (1995) indicates that the traditional role of the wife and
mother is responsible for the highest rates of stress and mental health problems.
Occupational Stressors
Unsurprisingly research has shown nursing, social work and work in the emergency
services to be the most stressful occupations Health Education Authority (1988)
probably due to the fact that these occupations usually involve responding to
uncontrollable and sometimes dangerous situations. Can you think of any other
highly stressful occupations?
Poor Health
Poor health can be very stressful, particularly if the illness is chronic or terminal. Pain
and discomfort can be both physiologically stressful (infections, viruses etc) or
psychologically stressful (poor quality of life, reduced social interaction and fear).
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Psychological Responses to Stress
These can take 3 forms:
• an emotional stress response
• a cognitive stress response
• a behavioural stress response.
Emotional Stress Response
Emotion invariably accompanies stress. Complex emotions can act as a stimulus
(stressor) a response (stress response) or both (transactional model). Certain emotions
are associated with stress namely embarrassment, fear, anxiety, depression,
excitement and frustration. These are known as the stress emotions. An individual’s
emotional response to stress is a result of physiological factors (fight or flight
syndrome) and individual appraisal of the situation (transactional model). Individual
differences exist with regard to emotional response to stress. A situation which one
person would find challenging and exciting may cause fear and anxiety in another.
Cognitive Stress Response
Stress reduces our ability to process information properly. If the stress is relatively
short lived then this should not present many problems. However, repeated exposure
to stress can have a hugely detrimental effect on cognitions (the way we think about
things). Negative thinking (no one likes me) is a cognitive stress response as is
catastrophic thinking (the world is going to end tomorrow and there is nothing I can
do about it). Negative and catastrophic thinking can have disastrous consequences on
cognitions and may actually increase the likelihood of experiencing stress. Negative
thought patterns may be the stimulus for or response to mental health problems such
as stress, depression or anxiety.
Behavioural Stress Response
Stress is similar to emotion and motivation. All have physiological and psychological
components that result in a change in behaviour. Below are some important
behavioural responses to stress.
Facial Expression: the emotional response to stress is likely to show in a change in
non-verbal communication communicating anger, fear, disgust, shock, anxiety, etc.
Body Language and Posture: emotional stress responses are apparent in our body
language and posture. A stressed individual may appear jittery, or adopt an aggressive
stance; the voice may change in pitch and tone. On the other hand, extreme stress can
also result in almost total lethargy.
Avoidance Behaviour: when a stressor is intense, an individual may come to fear the
stressor and try to avoid it. Confronting a stressor (particularly one which causes a
real threat to life and limb requires courage) and it is often easier to avoid the stressor
altogether. For example, rather than confront a bully at work or school, it is easier to
remove yourself from the situation - in this case resign or change schools. Extreme
examples of avoidance behaviour include drug abuse and in some tragic instances,
suicide.
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Anti-Social Behaviour - our stress response is not always pretty or rational. Many
individuals attempt to deal with stress by transferring their own negative emotions and
cognitions onto others. If they are frustrated in their desire to do something they rid
themselves of the stress this causes them by acting aggressively towards others.
How does Stress affect our Health?
We have seen that exposure to stress stimulates a physiological response (general
adaptation syndrome) which prepares us for emergency action (fight or flight
syndrome). Undoubtedly this is an extremely useful response. But what happens if
such a response is not required?
Stress may result in damage to the immune system. Repeated exposure to stress
seems to inhibit the production of endorphins (the body’s natural painkillers
manufactured by the pituitary gland). Research by Goetsch & Fuller (1995)
indicates that endorphins play a vital role in helping the body cope with stress.
Participants who were given a drug which inhibited the production of endorphins
showed increased anxiety, depression, lack of concentration and poorer levels of
overall functioning.
Repeated exposure to stress is also thought to inhibit the activity of lymphocytes
(Lim-fo-cites) which help fight off viruses and infections. We have probably all
experienced this. Think back to an important and stressful time in your lives for
example, preparing for exams. How many of you caught a cold or flu during or
shortly after that period of time? In many instances illnesses such as these are the
body’s outward response to an internally stressful event. However, they may perform
an important healing function. If you catch a cold or flu you are forced to endure a
period of relative inactivity (lying at home, watching television, sniffing into your
handkerchief, and being waited hand on foot by your mum or dad). This enforced
inactivity gives your body a chance to recharge physical and psychological batteries,
thus reducing your stress levels.
More disturbingly, recent research indicates that exposure to prolonged stress can
permanently change the structure of the hippocampus in the brain (McEwen, 1997).
In addition, a study reported in the Journal of the American Medical Association
recently has discovered that abuse in early childhood permanently changes the brain
chemistry of female victims. It is thought that abuse over stimulates stress hormones
to such an extent that these women are incapable of having a ‘normal’ stress response
in later life. Many suffer depression and anxiety which does not respond to treatment
and impairs their cognitive functioning, throughout their lifetime. Sadly, negative
thoughts themselves increase the likelihood of stress and so the cycle is perpetuated
again and again. The outlook for the mental and physical health of these individuals
is quite poor.
Parkes (1993) cites the following psychosocial changes as the most damaging to our
health:
• events which require us to make a major change in the way we view the
world
• events which have lasting consequences
• events which happen relatively quickly and allow us little time to adjust.
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For example, say a loved one died very suddenly and unexpectedly. This tragic event
meets all of the above criteria and, therefore, would be extremely stressful.
Individual differences involved in Stress
We all experience stress differently. Below are a number of important factors which
have a bearing on individual stress response and coping strategies.
Personality
Personality types can partially determine stress response. Friedman& Rosenman
(1974) divided personality types into three groups known as Type A Personality,
Type B personality and Type C Personality.
Type A personalities are usually competitive, impatient, hostile, insecure, highly
motivated, obeys rules and regulations without question.
Type A stress response: anger and hostility, inability to relax, excessive smoking,
drinking or drug taking.
Health problems associated with Type A: high risk of coronary heart disease and
high blood pressure, high cholesterol levels. Rosenman et al (1975) maintains that
type A men are two and a half times more likely to develop coronary heart disease
than type B personalities.
Type B personalities are usually relaxed, not excessively competitive, relatively
emotionally and psychologically secure.
Type B stress response: likely to be less hostile than Type A response and to result
in fewer health problems for the individual.
Type C personalities are usually passive, have difficulty expressing emotions.
Health problems associated with Type C personality: Research by Weinman
(1995) indicates that a difficulty in expressing emotion (particularly negative
emotions such as anger, fear and grief) can affect the ability to survive cancer.
Optimists Versus Pessimists
The Hardy Personality
The three traits associated with this personality type are a sense of commitment,
mastery of environment and willingness to embrace challenges (Kobasa, 1979).
Kobasa discovered that hardy people have good physical and psychological health.
The Optimist
‘Smile and the world smiles with you, cry and you cry alone’. There is a great deal of
evidence available which suggests that optimism has important health benefits.
Optimistic coronary-bypass patients heal faster than pessimistic patients (Scheier et
al, 1989). Optimistic students experience fewer physical symptoms at the end of term
(Aspinwall & Taylor, 1992).
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The Pessimist
Pessimists tend to suffer poorer physical and mental health. They are more likely to
respond emotionally to stress and experience negative emotions or guilt, distress and
shame. They tend to react defensively rather than positively to stressful situations.
Self-Esteem
If you value yourself then you are highly likely to have a positive outlook on life. This
affects the way you interact with your environment and the way your environment
interacts with you. People who appear confident are more likely to achieve their goals
in life because people are attracted to them. Those with low self esteem on the other
hand tend to adopt defensive coping strategies which may leave them isolated and
open to manipulation by others. Good self-esteem is vital in the fight against stress.
Cultural and Ethnic Factors
The environment we live in and the societal norms and values we are expected to
adhere to can cause a great deal of stress. Anderson (1991) defines three categories of
cultural stressors:
Level 1 Stressors
racism, overcrowding, poor living conditions and
excessive noise
Level 2 Stressors
major life events included in the SRRS
Level 3 Stressors
daily life events and hassles
Gender
From birth onwards men have a higher mortality rate than women (higher death
rates), however, women tend to suffer higher rates of morbidity (poor health). Why if
women suffer poorer health do they live longer than men? Several theorists argue that
women exhibit a weaker response to stress than men. Frankenhauser (1983)
compared male and female students adrenaline output in response to a stressful
situation and found that females produced less adrenaline than males. However,
females who are employed in ‘typically male’ occupations show the same adrenaline
output as their male colleagues (Frankenhauser et al, 1983). This suggests that the
difference between male and female stress response is learned via the socialisation
process rather than an innate difference. Esiler & Blalock (1991) suggest that
women suffer less stress than men because they are less likely to be Type A
personalities. However, other theorists state that women actually suffer more stress
than men, in their traditional roles. The difference may lie in the socialisation process.
Women are encouraged to be compliant and passive, men are encouraged to be
assertive, competitive and unemotional. It may be that male frustration manifests as
stress and aggression whilst women’s stress manifests as depression and anxiety.
Locus of Control
In general it is life events or situations which are outwith our control which cause us
the most stress. Humans exhibit a strong desire to control their destiny and dictate
their own actions. They do not enjoy being at the mercy of external forces. When
people expect to have control over a situation, but for some reason do not, the initial
response is often proactive, that is they will take positive steps to turn the situation to
their advantage.
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However, if they learn through repeated bad experiences that they are incapable of
changing the situation they may experience what is known as learned helplessness
Seligman (1975) which often manifests as stress or anxiety/depression disorders.
Research indicates that internals (individuals who believe that they are responsible
for their own destiny) are less likely to suffer an adverse physical reaction (they are
less likely to become ill) as a result of exposure to significant stressors than externals
(those who believe that their fate is controlled by external forces).
It follows that individuals who perceive that they have little control over their lives
(whether this is true or not) are likely to respond more negatively to stress.
Stress Reduction
What do you do when you are stressed? Do you hide away from the world, or go to
the gym for an invigorating workout? Perhaps you talk over the situation with close
family or friends? You may have a good cry or you may deny there is a problem at
all.
Cohen & Lazarus (1979) named five classes of coping strategy for dealing with
stress:
• Direct Action Response - a direct action response involves changing the
relationship between yourself and the source of stress. Examples: escaping from
the stress or removing the stress.
• Information Seeking - the most rational action, this involves the individual trying
to understand the situation and putting into place cognitive strategies to avoid it in
future. For example: imagine you were extremely stressed during an exam to the
extent that your performance was affected. Information seeking would involve
working out the reasons why. For example, ‘I was stressed because I didn’t revise
enough. I didn’t get enough sleep the night before the exam. I was convinced I
would fail.’ Once you had identified the reason you would take the appropriate
action to ensure that it did not happen again, e.g. you would revise properly, get
more sleep, or work on your self-esteem. Information seeking is a cognitive
response to stress. However, it is very difficult to be rational if you are suffering
from stress.
• Inhibition of Action - this involves doing nothing. In certain instances this may
well be the best response, particularly if the stressful situation is short-term.
However, in the long term this can be hugely detrimental and may have a negative
affect on your physical and mental health. An example of long-term inhibition of
action is a condition known as learned helplessness (Seligman, 1975). Learned
helplessness occurs when a person has learned through past experience that they
are powerless to change the situation they find themselves in, after a time they will
not even attempt to escape or take alternative action. This condition is often
evident in those who have been victims of domestic violence and abuse.
Individuals who exhibit learned helplessness often have very low self-esteem.
• Intrapsychic or Palliative Coping - this occurs when a person reappraises the
situation by means of psychological defence/coping mechanisms or through the
use of palliatives, i.e. sedatives, stimulants, or relaxation techniques (drugs,
alcohol, yoga, etc). Palliative coping is generally less helpful (in the long term)
than intrapsychic coping.
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Whilst reliance on psychotropic substances may be beneficial in the short-term,
long-term reliance does not reduce stress; it merely reduces negative physiological
and psychological symptoms, and gives the illusion of coping.
•
Turning to Others - The theory behind this is basically ‘a problem shared is a
problem halved’. Friends, family or trained counsellors can provide emotional
support at times of stress. Many people find this coping strategy helpful. Factors
of personality, gender and social environment will determine whether it is
acceptable to ask for help from others. For example, women are more likely to
use this as a means of coping with stress than men because it is more acceptable
for women to ask for help. The Type B personality is more likely to use this than
the Type A. Adequate and non-judgmental social support can provide an
important ‘safety valve’ against stress, depression and anxiety.
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Coping Mechanisms
Objectivity is the ability to separate one thought from another, or to separate our thoughts and feelings,
in order to enable us to evaluate our actions objectively and understand how we think and feel.
Defence mechanism: isolation.
Logical analysis is the ability to find explanations for our problems by systematically analysing them
and take measures to solve/resolve them based on a given set of circumstances (i.e. the reality of the
situation).
Defence mechanism: rationalisation.
Concentration is the ability to put aside unpleasant or uncomfortable feelings and thoughts in order to
focus on whatever requires attention at that time.
Defence mechanism: denial.
Empathy is the ability to pick up on other people’s feelings and tailor our actions/reactions to take
these into account.
Defence mechanism: projection.
Playfulness is the ability to use feelings, ideas and behaviour usually associated with childhood in
order to aid the solution of problems and to stimulate enjoyment of an otherwise serious experience
Defence mechanism: regression.
Tolerance of ambiguity is the ability to function in situations where we are unable to make clear
decisions because the situation is unclear or complicated.
Suppression is the ability to consciously forget about feelings and thoughts until the time comes when
it is appropriate to express them.
Defence mechanism: repression.
Substitution is the ability to consciously replace our true thoughts and feelings with those that meet the
demands of the situation.
Defence mechanism: reaction formation.
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Lazarus & Folkman (1984) maintain that effective coping depends on the situation.
They make a distinction between problem focussed coping and emotion focussed
coping.
Problem focussed coping involves taking direct action to solve the problem as in
direct action response, information seeking and, to a certain extent, turning to
others.
Emotion focussed coping involves trying to reduce the negative emotions associated
with stress as in intrapsychic or palliative coping. In general, individuals classed as
internals (those who believe that they are responsible for what happens to them) are
less vulnerable to stressful life events than those who believe that their lives are
controlled by fate, luck or significant others (externals) Johnson & Saranson
(1978). Internals tend to have high self-esteem and adopt problem focussed coping
strategies, externals tend to have low self-esteem and rely on emotion focussed coping
strategies. However, personality characteristics aside, some problems can best by
solved by using a combination of problem focussed and emotion focussed strategies.
The transactional/psychosocial model states that stress is a result of the interaction
between an individual and their environment coupled with their perception as to their
ability to cope with the situation. Studies have shown that we find it harder to cope
with situations that we believe to be outwith our control than those that we believe
that we can control. Collins, Baum & Singer (1983) undertook a survey of residents
of Three Mile Island (the site of a nuclear accident) . They discovered that residents
who experienced the most psychological problems after the event were those who
used the problem-focussed coping strategy. The situation was outwith the control of
individual residents, therefore problem focussed coping did not reduce the stress.
Individuals who used emotion focussed coping tended to fare better.
Knowledge of a stressor is also likely to reduce stress. Support for this theory comes
from two experiments by Brady (1958) and Weiss (1972).
Brady (1958) Executive Monkey Experiment:
This involved tying pairs of monkeys to an apparatus which delivered electric shocks
every 20 seconds. Each monkey could press a lever to avoid the shock. However, only
the ‘executive monkeys’ lever worked. The executive monkeys developed severe
ulcers and died.
Weiss (1972) repeated Brady’s with two differences
1) rats were used instead of monkeys, and
2) rats were warned of the shock before it happened.
Although the rats were stressed none of them died. Weiss concluded that knowledge
of a stressor reduces stress.
Contemporary theorists state that the transactional/psychosocial model offers the
most appropriate interpretation of stress, i.e. as a result of interaction between an
individual and their environment. Therefore, the most appropriate coping strategy (in
the majority of situations) is likely to be one which tackles external and internal
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factors. Stress is very rarely (if ever) solely the individual’s problem, however despite
this it was, and still is, commonplace to ‘blame the victim’.
Thankfully it appears that societal attitudes towards stress do appear to be changing,
albeit slowly. For example, there is increasing recognition of workplace stress as an
industrial disease and employers have a certain responsibility for prevention of it.
Making Stress work for You
At this point in time you may well be panicking. ‘I don’t know my dendrites from my
axons’. ‘What is motivation?’ Or worst case scenario ‘What is biological
psychology?’ If this is the case then you are probably getting stressed. Here are a few
friendly tips on how to deal with it:
1. Always remember stress is your friend as well as your enemy.
2. Listen to what your body and mind are telling you.
3. Do not try to be perfect (perfect people are very annoying!)
4. Take time out (axons, dendrites and biological psychology take time to
understand)
5. Talk to your friends or family. Do not try to struggle on alone with anything that
is worrying you.
6. Have fun (but don’t burn the candle at both ends)
7. Be optimistic (I can do this and I will succeed!)
8. Adopt a problem-solving approach.
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SUMMARY
Stress can be defined as a response to external demands that involve physical changes
in the body. Within this module we are concerned with four aspects of stress:
• stressors
• models and research of stress
• individual differences involved in stress, and
• coping with stress.
Stressors can be internal or external. Most people find that frustration, conflict,
poor health environmental and social factors can act as stressors. Catastrophic
life events are thought to cause the most stress as they involve us making substantial
changes to our lives often in a relatively short time. Stress is an interactive process
between the individual and the environment. Therefore, there are individual
differences in what is stressful; the perception of coping and control and the
strategies adopted (defensive or coping mechanisms).
The transactional model (Lazarus, 1965) emphasises the importance of such
appraisals.
Stress response falls into four categories:
• Physical
• Emotional
• Cognitive, and
• Behavioural.
Cannon (1932) is credited with identifying the emergency stress response known as
fight or flight response. Selye (1956, 1976) formulated the General Adaptation
Syndrome which has three main stages of stress response. Each stage involves
distinct physiological processes. The three stages are:
• Alarm
• Resistance, and
• Exhaustion.
Our body responds to stress by releasing hormones into the bloodstream. The
physiological models of Lazarus and Selye do not acknowledge the psychological
factors involved in stress. Biological psychologists now recognise that the perception
an individual has regarding an event is vital in determining whether they view it as
positively stressful or negatively stressful. In general optimistic and hardy
personalities cope better with stress than do pessimistic individuals. Optimists and
internals (those who believe that they control their destiny) tend to adopt
problem-solving strategies do deal with stress. Those with low self-esteem (externals,
those who believe they have little or no control over their live and pessimists) tend to
adopt emotive coping strategies to help themselves cope with the situation. However,
many situations require a stress response which involves problem focused and
emotion focused strategies. In general events which are out of the control of
individuals will cause stress in even the most positive person.
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Prolonged or extreme stress can inhibit the optimum functioning of the human
organism and inhibit the production of endorphins (natural painkillers) impair
cognitive functioning and leave the individual more vulnerable to physical ill health
(infections, flu viruses) or mental health problems (anxiety, depression).
However, despite the negative effects of stress, it can be a positive force, motivating
us to meet challenges take risks and perhaps most importantly of all escape potentially
dangerous situations. Stress can be the body’s friend as well as its enemy.
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QUICK QUIZ
1)
The stress response is entirely physiological. True/False?
2)
Men are more stressed than women. True/False?
3)
The Transactional model provides the best model regarding stress.
True/False?
4)
Stress involves a ........................ .......................... ............................
and....................response to a stressful situation.
5)
Optimists generally experience ............... stress than pessimists.
6)
The three stages of the General Adaptation Syndrome are .........................
.................... and ................................
7)
Prolonged exposure to stress can affect..................... health and
...................... health.
8)
Learned helplessness is a condition where ......................................................
9)
People who believe that they control their own destiny are known as
............................
10)
The fight or flight response is ..........................................................................
...........................................................................................................................
11)
Prolonged exposure to trauma in early childhood is said to affect the
............................. in the brain.
12)
Endorphins are the ................................................................ Stress does not
affect the production of endorphins. True/False?
13)
Problem focused coping strategies include
………………………………..........................................................................
………………………………………………..................................................
14)
Stress is always caused by negative emotions. True/False?
15)
Stress can be your enemy as well as your friend. True/False?
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GLOSSARY
Cognitions - the way we think about things.
Coping Strategy - the way we cope with stress can be problem focussed or emotion
focussed.
Endorphins - the body’s natural painkillers
Optimist - a person who looks on the bright side of life.
Palliative Coping - using drugs (anti-depressants, etc) to relieve stress.
Pessimist - a person with a negative outlook on life.
Stressors - things that cause us stress.
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ISSUES
The following issues may be studied in biological psychology:
• psychology as a science
• use of non-human animals in research
• hereditary and environment
• biological determinism
• mind/brain relationships.
For the purpose of this pack the issues covered will be use of non-human animals in
research and biological determinism.
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ISSUE 1: USE OF NON-HUMAN ANIMALS IN RESEARCH
Both human and non-human animals are used in biopsychological research. Rats are
the most common non-human subjects although mice, cats, dogs and nonhuman
primates (chimpanzees, etc) are also used. The use of animals in experiments is
highly controversial and many people including some scientists feel somewhat
uncomfortable with this procedure.
However, personal feelings aside using animals as subjects has some advantages,
namely:
1) Animals have simpler brain structures and less complex behaviour patterns.
Therefore, the study of animals is likely to reveal basic patterns of brain-behaviour
reaction.
2) Animal experiments allow us to compare the differences and similarities between
different species (the comparative approach).
3) It is possible to conduct research on laboratory animals that would not be possible
to conduct on ethical grounds on human subjects. For example: Brady’s
‘Executive Monkeys’ (1958).
Advantages of using Human Subjects
1) The greatest advantage in any study of the human brain function is quite simply
that we possess a human brain.
2) Humans are often cheaper to use.
3) Humans can report on their subjective experience.
4) In certain instances it is ethically less complicated - humans can give informed
consent i.e. using language.
Arguments which support the use of Animals
1) Certain animal species have a CNS which is very similar to humans in structure
and function, therefore, certain behaviour patterns (sleep, emotion) can be
assumed to be similar, allowing generalisations to humans.
2) Laboratory animals breed rapidly, therefore results are obtained quickly.
3) Using animals is cost-effective.
4) In general, laboratory animals are usually well treated.
5) Many experiments, do not involve suffering (e.g. maze learning).
6) In evolutionary terms, it is normal for one species to exploit another.
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7) If research on non-human animals were stopped, much human suffering would
continue which could otherwise be alleviated. Therefore a ban on animal research
would represent an infringement of human rights. As a species, humans have a
duty to each other to use whatever resources are available, including other species,
to improve our own well-being.
8) Animals do not feel pain in the same way as humans.
Arguments Opposed to the use of Non-Human Animals
1) Species are not similar enough, therefore, we cannot generalise findings to
humans.
2) Research on live animals is often unnecessary, e.g. for teaching purposes one can
use video or computer simulation. Tissue culture can be used for research.
3) We do not fully understand how and to what an extent an animal suffers pain. It is
difficult for humans to understand animal’s signs of distress.
4) Causing pain/distress is never justifiable, i.e. a moral absolute (Justin & Singer,
1976).
5) Exploiting animals for the benefit of humans is ‘speciesist’.
Ethical Implications of Animal Research
The Guidelines For The Use Of Animals In Research was published by the
Scientific Affairs Board Of The British Psychological Society in 1985. It contains the
following points which researchers should consider prior to embarking on
experiments on animal subjects.
Researchers should take care to:
1) minimise pain or discomfort to living animals,
2) consider whether the likely scientific contribution of the work justifies the use of
living animals, and
3) discuss any future research with experts in the field and their local Home Office
Inspector.
However, these guidelines themselves raise further questions namely, how do we
know that animals suffer and what goal can ever justify subjecting animals to pain?
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What Criteria Should Be Used To Judge Animal Suffering?
CRITERIA
EVIDENCE
Physical Health
Disease/injury e.g. executive monkey experiment (Brady,
1958 – see below) where a pair of monkeys gave electric
shock to the other with resulting ulcers and death would be
condemned by the scientific community today (Mapstone,
1991).
Mental Suffering
Does confinement (e.g. in a zoo) lead to mental suffering not
evident physically? (Dawkins, 1980). Zoo animals show
compulsive behaviour. Transporting food animals results in
subtle physiological effects.
Other means of
assessing animal
feelings
Animal behaviour may indicate feelings. For example, giving
pigs access to light switches at the Agricultural Research
Council showed they quickly selected the sort of lighting they
preferred.
Adapted from R Gross ‘Psychology, the Science of Mind and Behaviour’ 3rd ed.
London (Hodder and Stoughton)
Justification for Animal Experiments
Gray (1987) maintains that the main justification for animal experiments is :
1. the advance of scientific knowledge.
2. medical advances.
Ethical guidelines state that if the experiment requires the animal to be harmed,
stressed, confined or restrained in any way great care must be taken to ensure that the
end justifies the means. Experiments must not be undertaken just because it is
possible to do so. For example:
Brady’s 1958 Executive Monkey Experiment would not be sanctioned nowadays
because the motivation behind the research was to discover why business executives
develop stress. This is insufficient justification to expose animals to such suffering.
Experiments are often justified on the grounds of medical advances. However, what
may work on an animal subject may not work on a human subject. For example, the
drug thalidomide was tested on rabbits and subsequently approved for use as an
anti-nausea drug. Hundreds of pregnant women took this drug and ended up giving
birth to children with missing or deformed limbs. More recently the MMR (measles,
mumps and rubella triple vaccine) has been associated with Crohn’s disease and
autism (although nothing has been categorically proven). Presumably the vaccine
was tested on animals prior to use on humans.
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However, animal experiments have resulted in the development of drugs which could
not have been developed otherwise, most notably anti-cancer drugs, anti-depressant
drugs, anti-AIDS treatments and anaesthesia (Green, 1994).
Another argument against the comparative approach (comparing different species)
concerns the use of primates in research. It has been discovered that chimpanzees
possess almost identical brain structures to human beings. Researchers estimate that
chimpanzees share 98.4% of human brain structures and genetic inheritance. How
can we adopt the comparative approach on a species so similar to our own?
In conclusion, the use of non-human subjects in experiments will continue to arouse
strong emotions. From a psychological standpoint it has strengths and weaknesses and
in some instances it is the only possible approach available. However, technological
advances (in the form of PET, CAT and MRI scans) now allow us unprecedented
access to the brain. These in time may reduce the necessity of using animals in
research. However, it is likely that animals will continue to be used for testing of new
medical drugs and treatments. The utmost care must be taken to ensure that animals
do not suffer any physical or mental discomfort. Although the majority of scientists
do respect and care for their non-human subjects, some do not. Recently a newspaper
reported a story of a scientist who left a mouse with his skull clamped open and his
brain exposed for over 48 hours. The mouse was discovered by two of the scientists
colleagues who humanely destroyed the mouse and reported the colleague to their
superior. He subsequently lost his job.
Exercise 1:
Divide the class into two groups one who has to put the case for the use of non-human
animals in experiments and one who has to argue against such a practice.
Exercise 2:
You are a parent whose son/daughter is suffering from a currently incurable condition.
Would you allow him/her to be treated with a drug tested on animals? If not why not?
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ISSUE 2: BIOLOGICAL DETERMINISM
In order to be classed as an objective ‘science’ psychology has struggled to remain
value free. Given the fact the psychology is concerned with the human mind and
behaviour this has proved somewhat difficult. Humans can be objective and rational
but often they are not.
Biological determinism refers to the idea that ‘biology is destiny’. Men and women
are naturally different and, therefore, suited to different roles (the MAMAWAW
theory). Darwin’s Theory of Evolution was a determinist theory as was early
biological psychology and Freud’s psychoanalytic theory.
Some Biologically Determinist Views and Myths
1. Males are genetically predisposed towards aggressive behaviour due to the
influence of testosterone on the brain.
2. Women are naturally predisposed towards nurturing and caring roles.
3. Men are biologically determined to be better at spatial tasks than women (maths,
physics, etc).
4. Women have smaller brains than men therefore they are naturally intellectually
inferior.
5. Women’s hormones are responsible for their lack of intellectual achievement and
‘irrational behaviour’.
6. We are biologically predisposed towards survival of the species, therefore,
homosexuality, bisexuality, asexuality and transsexualism are ‘unnatural
behaviours’.
7. Women are the weaker sex, suffering poorer mental and physical health than men
do.
8. Men are biologically programmed to rape to ensure the survival of the species.
9. ‘Big boys don’t cry’. Men are naturally less emotional than women.
10. Mental illness is a result of neurobiological malfunction.
As the above examples show, men and women are often presented as two quite
separate and distinct categories. Biological factors have been used to explain different
social roles and behaviour and often provide the justification for treating men and
women differently. Many of the societal norms and values to which we are expected
to adhere are based on biological determinism.
This can be dangerous and misleading. Our behaviour is a result of a complex
interaction between biological, emotional, intellectual and social factors. A few
examples are examined over.
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•
Males are biologically predisposed to be aggressive
Although men are generally involved in more aggressive acts, the idea that there is a
biological basis towards aggression has not been conclusively demonstrated. Research
indicates that although gender differences are relatively large when we consider
physical aggression, studies have shown that women are more likely to show indirect
aggression than men (social manipulation, scape-goating, ostracism and gossiping)
(Hines & Fry, 1994). In addition, gender differences between men and women are
relatively small when there is justification for the aggression.
For example, Zur & Morrison (1989) gave students a questionnaire about war. One
of the statements was ‘Any country which violates the rights of innocent children
should be invaded’. There was no significant difference between male and female
responses to this question. Lightdale & Prentice (1994) have also shown that there is
little difference in the aggressive behaviour of men and women when the
perpetrator/victim is anonymous. These findings and others indicate that aggressive
behaviour is more socially acceptable for men than women. The socialisation process
may be more relevant in influencing aggression than testosterone levels.
•
Women are naturally predisposed towards nurturing and caring roles
Feminist psychologists would argue that this is a social construction rather than a
biological imperative. There is no evidence to support the notion that women are
naturally more caring than men. Assuming a biological basis for this behaviour has
merely resulted in keeping women in the home and men in the workplace. If you
practice at anything, you improve. Men are not expected to nurture but it does not
mean that they cannot do it. Further evidence against a biological basis for nurturing
and caring comes from the fact that increasing numbers of women are choosing not to
raise a family.
•
Men are better at spatial tasks than women
Again this has not been conclusively demonstrated. Kimball (1989) found that
females tend to receive better marks in mathematical classes than males. However,
Kimura (1987) found that men perform best on spatial tasks if they have low levels
of testosterone, females tend to perform better if they have high levels of testosterone.
It may be that spatial task performance is affected by both biological and
environmental factors. Research has indicated that teachers are more likely to spend
time with boys discussing mathematics than girls (Leinhardt et al, 1979). Research
in the field of Biological psychology proposes that differences in spatial ability
between boys and girls may be explained by the fact that boys are given toys which
aid their spatial development (construction toys, building blocks, model aeroplanes,
etc) girls tend to be given toys which relate to their role in life (ironing board, doll,
pram).
•
Women have smaller brains and are therefore intellectually inferior
Early research inspired by evolutionary theory stated that the highest mental
capacities were located in the frontal lobes of the brain, research showed that men had
bigger frontal lobes than women. Therefore, ‘men were naturally more intelligent
than women’.
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However, some years later, researchers stated that higher mental capacities were
actually located in the parietal lobes. Strangely enough research now showed that
women had larger frontal lobes than men. Current research (James, 1994) indicates
that men and women are similar in intellectual functioning and that women are
superior on certain cognitive tasks.
•
Women’s hormones are responsible for their irrational behaviour
Dalton (1979) states that in the week prior to menstruation, fluctuation in hormones
has a significant affect on female functioning. Women suffer cognitive impairment
and are more likely to commit crime, beat their children and attempt suicide at this
time. However, many women do not exhibit such behaviours. Hormone levels are
very difficult to measure and it is impossible to determine whether this behaviour is
entirely biologically determined. What is known is that many women who suffer from
pre-menstrual syndrome are also suffering from stress and or depression. Irrational
behaviour is again both biologically and environmentally influenced.
•
Heterosexuality is the only ‘Natural’ Sexual Behaviour
This statement proposes that anything other than heterosexual orientation is deviant
sexual orientation. Research has indicated that prenatal hormones are instrumental in
determining sexual orientation. If we were biologically determined solely to ensure
the survival of the species, then there would be no homosexuality. The notion of
‘abnormal sexuality’ is a value judgement. Research has indicated that there may
indeed be a biological/genetic basis for homosexuality rendering it ‘natural’ (Byne,
1994). Research by Hamer et al (1993) attempts to explain male sexual orientation in
terms of the specific structure of the X chromosome.
•
Women are the weaker sex suffering poorer mental and physical health than
men
Women do visit their doctors more than men. However, this does not necessarily
mean that they suffer poorer health. Society encourages women to depend on the
judgement of others. Men are encouraged to be stoical and not to complain. Women
are also supposed to be biologically predisposed to depression due to lower levels of
serotonin in their brain. However, recent figures published by The Samaritans
indicate that 75% of all suicides in the United Kingdom and Ireland are male.
Cultural attributes of machismo make it unacceptable for men to admit to suffering
from ill health.
•
Men are biologically predisposed to rape
Rape is a complex topic which cannot be explained by biological factors alone. If
men are biologically programmed to rape, then why do not all men rape? Rape is
about power rather than sexual desire or biological drive.
Society has encouraged men to believe that they are the dominant species, therefore,
the motivation to rape may be cognitive (to increase their self-esteem), emotional (to
release anger and frustration) or behavioural (to assert their power and dominance)
rather than a strictly biological imperative.
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•
Men Are Less Emotional Than Women
This is potentially one of the most damaging views of all. Men are not encouraged to
show their emotions. They learn through the socialisation process that admitting to
weakness or showing fear is ‘unmanly’. Repressing these emotions may have a
hugely detrimental effect on the mental and physical health of men, and can have a
detrimental effect on their interpersonal relationships.
•
Mental Illness is a Result of Neurobiological Malfunction
There is evidence to support a biological basis for some forms of mental illness.
However, it cannot be explained by biology alone. Most contemporary theorists agree
that mental illness is a result of biological and environmental stressors.
Biological determinism is a reductionist theory. It has often been used to enforce
political and social values. Biology however is only a part of our destiny. What we
are and what we become is a result of our personality, environmental adaptation,
genetic inheritance and biological predisposition.
Theoretical Implications of Biological Determinism
Biological explanations are deterministic in that they regard our behaviour and
experience as being “controlled” by our genes, nervous system and hormones rather
than seeing individuals as making free decisions on how to act on their environment.
This can have important consequences for, for example violent criminals - are they
responsible for their crimes, or do we blame their ‘genes’? If their genes are to blame
does this mean that some people will never resort to violent crime regardless of
situational factors? If certain criminals are genetically predisposed to violence, what
action should we take? Should we imprison them en masse regardless of whether
they have committed a crime (just in case they do) or do we have any right to
imprison them for something which is outwith their control? If we take this argument
to its logical conclusion, do individual’s carrying the ‘violent crime’ gene have a right
to have children who are highly likely to have inherited anti-social tendencies?
Should society enforce sterilisation programmes for these unfortunates in order to
safeguard society as a whole?
In the same vein, if homosexuality is genetically determined how should society treat
homosexuals? How can we overcome social norms which imply covertly that
‘homosexuals are unnatural’? How would organised religion which has fought a long
and vehement battle against homosexual priests and vicars, react to the ‘proof’ that
homosexuality was genetically determined and, therefore, according to religious
ideology ordained by God?
Biological explanations are reductionist and potentially harmful in underestimating
the influence of social/environmental factors; if as some believe, intelligence is
genetically determined, why bother educating innately ‘inferior’ individuals?
Finally biological explanations emphasise the extent to which behaviour is the result
of biology, and in assuming that our biology is immutable, fails to recognise that the
reverse is also true, i.e. our behaviour and experience alters the structure and functions
of the brain.
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Exercise 1
Evaluate biological determinism as a theory and argue the case for or against it.
Exercise 2
Identify biologically determinist theories and the consequences for the individual and
society in adhering to them.
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BIBLIOGRAPHY
There are a number of books you may find helpful when studying biological
psychology.
Bernstein et al: Psychology 4th Edition - Chapter 3.
Breedlove, S.M (1994): Sexual differentiation of the Human Brain. Annual Review
of Psychology, 45, 389-418.
Changeux, J.P (1993, November): Chemical Signalling in the Brain. Scientific
American, 269, 58-62.
Dawkins, R (1976): The Selfish Gene, Oxford University Press.
Gross, R (1996): Psychology - The Science Of Mind And Behaviour 3rd Edition.
Lea. S.E.G (1984): Instinct, Environment and Behaviour: Methuen Press.
Matlin, M (1996): The Psychology of Women 3rd Edition. Harcourt Brace Publishers.
McCaugh, J (1971): Psychobiology Behaviour from a Biological Perspective,
Academic Press.
Pinel, J (1997): Biopsychology 3rd Edition.
Plomin, R (1990): Nature and Nurture: An Introduction To Human Behavioural
genetics: Pacific Grove, CA: Brooks/Cole.
Woods, S.C & Strubbe, J.H (1994): The Psychobiology of Eating. Psychonomic
Bulletin & Review, 1 141-155.
In addition there are a number of very good web sites which deal with biological
psychology. The best ones are generally accessed via yahoo or alta vista.
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