BIOLOGICAL PSYCHOLOGY: UNIT 2
Bio key assumptions
1) The importance of genetic influences on behaviour:
The physiological approach see us as being to a large extent who and what we are by the genes
inherited from our parents. We inherit 50% of our genes from our mother and 50% from our father.
The more closely related two people are the more likely they will share the same characteristics (e.g.
IQ, height, schizophrenia etc). A person has their ‘nature’ which is given to them by their genes, and a
‘nurture’ which is given to them by their environment.
2) The role of neurotransmitters on behaviour:
The central nervous system consists of our brain and spinal cord. The automatic nervous system
(ANS) which controls functions of the body such as the heart, lungs etc, which we have no conscious
control. The Peripheral nervous system (PNS) controls those parts of the body to which we have
conscious control such as flexing muscles. The brain guides behaviour through neurotransmitter
functioning.
3) Brain Structure and behaviour:
The brain has many parts, hippocampus is thought to be where STM occurs, and the hypothalamus
produces hormones that influences gender during pregnancy. The brain is in 2 halves, joined by a
mass of bundles called the corpus callosum. Brain lateralisation is the term used for considering the
two halves of the brain separately and studies have shown that males and females use these
hemispheres differently
The central nervous system
 Our nervous system is activated when we receive a stimulus from the
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environment and respond to it, the messages are transmitted by a series of
electrical impulses through nerve cells. Neurotransmitters are chemical
messengers that travel in the brain between neurons.
An electrical impulse travels down the axon and releases the neurotransmitter
into the synaptic gap
The receptors on the nearby dendrite receives the neurotransmitter if it ‘fits’ or
not. (lock and key)
If it is not taken up the message is stopped
If it is taken up the message continues to travel down that neuron’s axon so the
message continues
Key definitions recap
Central Nervous System (CNS) consists of the brain and the spinal chord and controls much of our behaviour
by passing electrical impulses around the body through nerve fibres made up of tracts of neurones.
Neurones are tiny nerve cells that communicate messages in the brain and around the rest of the body through
impulses passed around the nervous system via synapses.
A synapse is a junction between two neurones where messages are passed from one neurone to another. These
messages are passed through neurotransmitters which move from the terminal button of one neurone, to the
receptors on the dendrite of another neurone.
Neurotransmitters are chemicals that are released by neurones into the synaptic gap. Receptors (protein
molecules situated on the membrane of the neurone) on adjacent neurones allow the neurotransmitter to attach to
them if the neurotransmitter is the right shape to fit that particular receptor. This then changes the chemical
makeup of the neurone and therefore its voltage causing an electric charge to pass down the axon of the neurone
(called an action potential). When the charge gets to the terminal buttons at the bottom of the axon it causes
neurotransmitters held within that neurone to be released into the synapse.
A Hormone is a chemical which is released from a gland, travels in the blood and affects target organs such as
muscles, sex organs or other glands. For example sex hormones, such as oestrogen and testosterone are released
by the gonads (sex organs). Oestrogen is produced by the ovaries in sexually mature females and testosterone is
produced by the testes in sexually mature males (although a little of each is produced by both sexes). These
hormones are responsible for many of the changes that occur around puberty such as the deepening of the voice
in males and the onset of menstruation in females.
Brain lateralisation refers to the uneven distribution of tasks carried out by the hemispheres. Lateral means
side. Any function, e.g. language, which is found on one side of the brain is called a lateralised function
Genes are units of information that are inherited from our parents. They control, or influence characteristics such
as risk of mental health disorders, personality and sexual development. Genes are sections of strands of a
chemical called DNA found in our cells.
METHODOLOGY
Twin and Adoption Studies
Both these methods are designed to separate nature from nurture. Twin studies change the genes and keep the
environment steady, whereas adoption studies keep the genes steady and change the environment.
Twin Studies
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Twin studies are a research design which involve comparing identical (MZ) and non identical twins (DZ) in order
to determine the importance of genes and the environment on individual traits and behaviours.
Twin studies compare the amount of behavioural similarity between two types of twins – monozygotic twins and
dizygotic twins
Monozygotic (MZ) twins are genetically identical as they both developed from the same egg. Dizygotic (DZ) twins
only share 50% genes so are as genetically related as ordinary siblings.
Both types of twin will however share very similar environments as are born at the same time to the same family
so will be treated the same. Any differences in the amount of behavioural similarity shared by each type of twin
must therefore be due to the difference in genetic makeup. So if the behaviour of MZ twins is more similar than
the behaviour of DZ twins we assume it is because they are genetically identical and therefore behaviour is a
product of nature, not nurture.
An example of twin studies is research into schizophrenia which has found that monozygotic twins have a higher
concordance rate of schizophrenia than dizygotic twins suggesting that schizophrenia must have a genetic
element.
Sometimes MZ twins are separated at birth and raised in different environments. They can be traced and tested
for behavioural similarities to each other. Similar behaviour is therefore likely to be due to genetic
influences. These cases though are quite rare.
Evaluation of Twin
A strength of twin studies is that they provide a good natural experiment as nurture is kept
constant whilst genetic makeup varies so any differences between twins can credibly be
assumed to be due to nature. For example monozygotic twins have been found to have a
higher concordance rate for schizophrenia than dizygotic twins which clearly shows that
schizophrenia does have a genetic element.
A further strength of twin studies is that twin studies are highly true to life as nothing in the
environment is directly manipulated. The findings are naturally occurring and we can
therefore generalise the findings to their real situations as they are not artificial. Furthermore,
twin studies often collect a lot of data which is usually both quantitative and qualitative.
A weakness of twin studies is that they may suffer from a sampling bias. Twins used in
research often answer advertisements, therefore they are a volunteer sample, meaning that
they might only represent a certain type of person rather than be truly representative.
A further weakness of twin studies is that MZ twins, because they look the same, are in fact
treated more like each other than DZ twins who don’t look the same, therefore MZ may have
more similar environments too making it hard to draw conclusions about the role of nature
and nurture.
Adoption studies
An adoption study tracks the behaviour of children adopted away from their
biological parents at a young age. It looks for similarities between the child and
their biological parents and their adoptive parents.
If adoptive children are more like their biological parents then we attribute the
behaviour to nature – it is in the genes, but if they are more similar to their adoptive
parents then it is due to nurture.
Evaluation
A strength of adoption studies is that these
studies tend to be quite ethical because there is
no direct manipulation of the participants. The
adoption occurs naturally so the psychologists
simply track and measure behaviour.
A further strength of adoption studies is that
adoption studies are highly true to life as nothing
in the environment is directly manipulated by the
psychologists. The findings are naturally occurring
and we can therefore generalise the findings to
other real situations as they are not artificial.
Furthermore, adoption studies often collect a lot
of data which is usually both quantitative and
qualitative.
A weakness of adoption studies is that in practise
adoption agencies try and place children with families
similar to their birth family; this means that there is not a
complete change of nurture, so it may overestimate the
role of nature in causing any similarities between the
children and their birth parents.
A further weakness of adoption studies is that they may
suffer from a sampling bias. Adopted participants used in
research often answer advertisements, therefore they are
a volunteer sample, meaning that they might only
represent a certain type of person rather than be truly
representative.
PET and MRI Scanning Techniques
Brain scanning techniques are a major advance in biological psychology. They allow
researchers to examine the brains of living people and draw conclusions about the
relationship between brain structure/activity and behaviour. There are two basic types of
scan: functional e.g. PET and structural e.g. MRI. Structural scans take detailed pictures of
the structure of the brain and functional ones show activity levels.
Magnetic Resonance Imaging (MRI) Scans
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These are a form of structural scan that shows a
picture of the brain inside the skull so that
specialists can identify any areas of damage or
tumours.
They allow a real, living brain to be seen without
having to cut into the head of the patient.
Patients are placed in a very large scanner that
sends a strong magnetic field through their
head.
The magnetic field causes the nuclei in hydrogen
molecules in the brain to spin in a particular way,
and this is picked up by the scanner.
Because hydrogen concentrations vary in
different parts of the brain, it is possible for the
scanner to produce a detailed image of the brain
based on the amount of hydrogen molecules it
identifies in different areas.
Positron Emission Tomography (PET) Scans
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PET scans are functional scans that show images
that can illustrate how the brain is working during
different tasks.
By identifying areas that are not working properly,
doctors can see areas that are damaged or areas
affected by tumours.
Patients are injected with water or glucose that
has been labelled with a radioactive tracer
substance. The substance travels around the
body until it reaches the brain where the brain
uses up the water or glucose as energy and the
tracer begins to decay. As the tracer decays, it
gives off positrons, so the more energy being
used in different areas, the more positrons are
being emitted. The positrons collide with
electrons and form gamma rays that are picked
up by the scanner and show the amount of
energy being used by different areas of the brain
Using animals in experiments
Describe
 Animals are used in a number of areas of study (language, memory and learning) in particular
how the brain works and the effects of genes.
 Laboratory experiments with animal subjects are essentially the same as with human
participants. An independent variable is manipulated in one condition and its effect is measured
on the dependent variable and compared to the dependent variable in other conditions in order to
establish cause and effect. All other variables are controlled and held constant across the
conditions.
 Animals are used when the independent variable is invasive and it would be unethical to apply it
to humans e.g. administering a drug to see its effect on behaviour or to gain the maximum control
over variables other than the independent variable/dependent variable e.g. animals can have all
aspects of their lives controlled for the purpose of the experiment and you can breed animals for
the experiment that are genetically similar so as you can remove the chance of individual
differences affecting the results
 Consider, ethics, practical issues and credibility. (Pavlov’s dogs and Skinner’s superstitious
pigeons are good examples to use)
Using animals in experiments
Evaluate
PRACTICAL ISSUES
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FOR
Small and easy to handle
Short reproductive cycles
Similar brain structure to humans
Short lifespan
Strict control of procedures
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AGAINST
Brains are not going to be identical to humans
Genetic structures are not the same
Human lives are complex
Some diseases have to be replicated in animals using drugs and
so might not be the same thing
ETHICAL ISSUES
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REASONS WHY
possible to carry out some procedures that you cant
do on humans (Cutting/damaging parts of the brain)
should protect humans first, animals come second
Drugs have been developed that could not have been
developed otherwise - treatments
Knowledge obtained helps animals as well as
humans
GUIDELINES
3R’s
Bateson Cube
A – Anaesthetic given
N – non animal expts cant be used
I – important enough to justify?
M – minimum used
A – appropriate accommodation
L – legislation followed
S – specialist and competent staff
CREDIBILITY
SUBJECTIVE
Does the data make sense to draw conclusions from
animals to humans?
Using animals can be seen as lacking credibility
because people think that animals are too different to
humans for the results to apply
OBJECTIVE
How strong is the data in respect of how good the
methodology is.
Using animals is scientific because there can be controls
and studies can be repeated to make sure the findings
are reliable.
KEY STUDIES
Money 1975
Aims: Wanted to find out about sex reassignment
Case Background/procedure: looked at an MZ boy (David Reimer) brought up as a girl
after a circumcision went wrong
Case Description: The baby’s penis was burnt off accidentally because the electric
current was too strong. The parents contacted Money and chose to go for sex
reassignment. They treated ‘Brenda’ as a girl and encouraged her to be socialized in
female role. Hormone replacement therapy and surgery was used as child developed.
‘Brenda’ was reported to have tomboy traits and being physically active. Could you add
any specifics in here?
Case analysis: Money concluded that a normal XY baby could be successfully nurtured as
a girl and therefore stronger than nature. ‘Brenda’ was told the whole story at 15yrs and
it emerged that she was never happy as a girl. His mother attempted suicide and his
father turned to alcohol. His brother became clinically depressed so the family was
under enormous pressure. ‘Brenda’ underwent surgery, was depressed and attempted
suicide himself. However, he married and had a job. His brother died of an overdose and
David had marital problems and eventually committed suicide.
Money Evaluation
Strengths:
V - Case is detailed and longitudinal
giving it validity.
Qualitative data from various sources Observation, questionnaires and
interviews from parents as well as
Brenda’s self report.
G - This was a real-life case that was
reported by Money so it has high
ecological validity because the boy’s
life and the events that happened to
him were all real.
A – due to the type of twin study it was
it provided a unique opportunity to test
the effects of nature versus nurture on
gender development due to the
matched control of a genetically
identical twin. This meant that it was
possible to compare the gender
identity of the two boys who had
identical genetic make-up but were
brought up differently.
Weakness:
G - Hard to generalise as unique case.
R - David was not typical of other children in a number of ways.
For example David had an identical twin brother which may have
also influenced his gender behaviour and his identical twin
brother suffered from schizophrenia which it is believed is partly
caused by genes
V - David was not happy as a girl so no validity
V / R - Concerns the subjectivity and bias of the psychologist
carrying out the study. It is very possible that Money interpreted
the findings as to fit in with his gender neutrality theory. It is
argued that behaviour of the twins was misreported by Money
who claimed that the study was successful in the reassignment
of Bruce’s gender. David’s later testimony does suggest that
Money’s was bias and misreported the findings
E - ethical issues surround this case study. The twins were
allegedly encouraged to pose naked in sexual positions which
they said was degrading Being involved in the case study was
alleged to have been a factor in the mental break down of Brian
Reimer, and the later suicide of David. It has been argued that
Money coerced Bruce’s parents into allowing him to study the
case and that the study’s reported findings were manipulated by
Money for his own gain and the potential effect on the children
was ignored.
Raine 1997
A: Wanted to find out about brain differences between murderers pleading NGRI and nonmurderers.
P: Sample and Design: 41 murderers charged with manslaughter. 23 had history of brain
damage, 6 with schizophrenia, 3 with substance abuse, 2 with mood disorder, 2 with
epilepsy , 3 with learning disability and 2 with paranoid personality.
The control group was matched for these features. The study took place in a University in
USA.
IV = whether participant was a murderer or not
DV = various measures of brain activity
Each PPt carried out a practice test and then injected with a trace, then given more tests.
After ½ hr a PET scan was taken. Slices of the scan were checked for glucose levels and
compared with the controls.
R: murderers had lower glucose metabolism in some prefrontal areas. There were no
differences in the temporal lobe. The murderers had lower glucose in the corpus callosum
and had different levels of activity in the area of the brain linked to aggression
C: murderers have lower glucose activity levels and abnormal activity in other areas.
Suggest biological cause. Could not conclude biological cause for violence just a
predisposition for it depending on the environmental triggers (nurture).
Raine Evaluation
Strengths:
R – High amount of control - For example
they used a control group who were
matched on variables such as age and
sex and they were screened for their
physical and mental health. Such
standardised procedures allow for
replicability and further studies have
been carried out by Raine gaining similar
results therefore improving the reliability
of the findings
V / R - PET scans allow for a wide range
of non intrusive studies and importantly
provide a large amount of quantitative
and objective measures of brain activity
from which sophisticated analysis can be
complete
G - Sample size is large enough for
generalisation to murderers pleading
NGRI
Weakness:
A / V - natural experiment, which means that the
researchers could not randomly allocate participants to
either of the two conditions. Therefore we have to be careful
in making cause and effect statements. It is possible that
any differences in brain activity between the two groups
could have been caused by other factors. We can only say
that the study shows a correlation and not a causal
relationship. For example, it could be that the differences
between the two groups might have been a result of the
crime and its consequences rather than a cause of it.
V - PET scans cannot give us valid or subjective data about
how a person is actually thinking. Although we can see an
objective measure of murderers brain activity we do not
know what they are thinking. We have to infer the thought
patterns from different levels of activity in different parts of
the brain
G - the task used by the participants before the scan is a
general activity task and has no bearing on violent acts or
even the decision to be violent – lacks mundane realism
Lab study lacks ecological validity especially when
considering the environment when they committed their
crime
Also there were no violent criminals in control group so hard
to generalise beyond study
GENDER DEVELOPMENT
SEX DIFFERENTIATION
Gender= social term that refers to the norms and rules of being male or female
Sex = biological term that refers to our genetic sex, male or female.
 We have 23 pairs of chromosomes, each pair comes from our mother or father. (50%) a
male baby receives (XY) and female (XX).
 An embryo generates hormones within 8 weeks. The hormones influence the sex of the
baby. Hormones also carry messages and are produced by the endocrine gland. They
travel in the blood and are a lot slower than neurotransmitters.
 Sex differentiation goes through 4 steps
1. Fertilization determines the genetic sex (XX) or (XY)
2. During development the sex organs grow and a gonadal ridge develops. External genitalia look
female.
3. Hormones (androgens) start affecting how the fetus develops
Testosterone
andinandrogens
FEMALES:
and progesterone
4.MALES:
The gonadal
ridge changes,
males testes are
developed, Oestrogen
in females ovaries
develop
BRAIN LATERALISATION
 There are brain differences between males and females.
 The brain is divided into 2 hemispheres which are joined by the corpus callosum
which is larger in women.
 The left half controls language and the right is concerned with visuospatial ability and
perception.
 Evidence comes from scanning techniques:
 If male has damage to RH then visuospatial tasks are affected
 Men who do not have normal exposure to androgens tend to use both sides of the brain
more
 High levels of testosterone means slower neuron growth in the LH which supports males
using the RH more.
Strengths of biological explanation of
Weakness of biological explanation of
gender development:
+ high reliability because studies are
replicable.
+ Any experiment using animals or humans
are objective and scientific.
+ There is validity because different studies
use different research methods have similar
findings. (MRI scans, lab expt etc.)
gender development:
- difficult to generalise because many
findings come from animal studies.
- There are important differences in the
human brain so findings not credible.
- Can’t ignore influence of the environment
in behaviour
KEY ISSUES
The debate over whether transgender operations are ethical
Outline of the issue
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A transgender operation involves changing the physical sex of a person, e.g. changing a male into a female
physically
This can be done with adults because they feel they are in the wrong sex body
It can also be done on children if they appear to be of an indeterminate sex
However in the case of children there are ethical issues as it is the parents not the child who decides what sex
they become
Some argue it isn’t ethical to spend public money on what could be seen as a non essential operation
Application
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In the case of Money’s study at first it seemed that a male could successfully become a female
However in David Reimer’s later testimony it was clear it didn’t work as he changed back to a male
The case of Daphne Went would suggest it does work as she is biologically male but happy as a female
If gender is partly due to brain lateralisation then such operations won’t work as the child will still have the
original sex brain
However social learning theorists would argue that with appropriate role models children can learn to be a
specific sex
A study of 14 males who were raised as girls after surgery found that most of them still felt male showing it
often doesn’t work
Is autism an extreme male brain condition?
Description
 Autism affects a child’s ability to interact and build relationships with others
 Symptoms can include lower language abilities than others their age and problems with
communicating
 Almost ¾ of people with autism are male
 It is thought that an autistic brain structure is an exaggeration of normal male brain structures
Application
 Male brains are heavier than female brains, and people with autism have heavier brains
 In early development male brains grow faster than female brains and the brains of people with
autism grow even faster
 Males are better at spatial tasks than females, and people with autism tend to be even better
at them showing it could be due to brain function
 People with autism are slower than males who don’t have autism at developing language, with
females developing language the fastest
 However hormones could play a part as it could be due to exposure to male hormones which
explains why some females also have autism
 It may also be genetic as about 60% of MZ twins will have it if their twin already has it
Bio Practical
Aim: to investigate the difference in spatial skills abilities between males and females using a psychometric spatial
skills test
Background: Spatial ability is required in technical and design jobs where drawings and plans are used such as
architecture, surveying, engineering and design. It is also important in our everyday lives for things such as parking a
car and map reading. Some men have long held that women are deficient in these skills. Many women have
disagreed! Spatial skill is the ability to assess and orientate shapes and spaces.
More can be found in your “How Science Works” packs
? Could it be that spatial skills such as map reading and parking may be difficult for some women because they had
too little testosterone in the womb?
Some of you looked at gender differences others looked at length of ring and index finger. Ensure you have a
hypothesis in relation to your study – italics below are dependent on which one you did
Procedure
Participants were approached in the class and asked if they would consent to take part in a study on spatial ability.
Pps were briefed and gave verbal standardised instructions. Pps were then asked to stay quiet and given the spatial
awareness task to complete. This consisted of a number of shape rotation tasks to see which shape matched a
number of rotated alternatives. Pps were given 10 minutes to complete the test, which was timed. Participants were
asked to write their sex – male/female on their answer sheet but not their name. They then examined their own ring
finger to see if it was shorter/longer/the same as their index finger. This was also marked on the answer sheet.
Pps answers were then scored and a total obtained for each pp.
Can you answer these questions?
What were the IVs? How was the DV measured? What sampling method was used? How many male pps were there?
How many female pps were there? Who were your pps? Age range / occupation / target population. What is the
research method? What is the research?
(We completed the statistical test to get an observed (or calculated) value. If we are conducting a Mann Whitney U
test it is called the U value. To know if this is significant, we need two pieces of information:
1.Did the study have a directional (one tailed) or non directional (two tailed) hypothesis?
2.How many _________________ are in each group. We call this N1 and N2 (N1 is usually the smaller group)
Using this information, we compare our observed value (the one you calculate) with the critical value from the
table. If the observed value is equal to or higher than the critical value, we accept the experimental hypothesis and
reject the null hypothesis. If the results are not statistically significant then we accept the Null and reject the
experimental hypothesis.(NB: if our result is significant, but in the opposite direction than that which we
predicted, i.e. girls are better at spatial awareness tasks than boys then we still have to reject the experimental
hypothesis).
NB: If the number on the table of critical values is lower than U (your observed or calculated value),
it is not significant. If the number on the table of critical values is equal to or higher than U, then the
result is significant.
Results: What where the results of your analysis.
Calculated U (observed value)= _____
Critical value for significance at 0.05 = ___________ (directional hypothesis)
Calculated U is greater/less than the critical value of U. Therefore this is/is not significant at 5% level.
P≤/≥0.05. This means the probability of the results being a fluke is greater / less than 5%. This means we
are/are not 95% sure that the IV had an effect on the DV.
Conclusions: State your conclusions, including statements of significance relating to the hypothesis.
The experimental results were/were not significant at the 5% level therefore the experimental hypothesis can
be ____________ and the null hypothesis __________________. The results do not support/support the
hypothesis that males perform better on spatial awareness tasks.
Evaluation of Practical
G - could refer to how far the sample represents the target population. As our hypothesis
states that males perform better on spatial awareness tasks, then we would need to look at
our sample to see if it is representative of males and females
Who was the target population?
Was there an equal distribution of males and females?
Was the sample big enough for us to generalise our findings?
Was there a wide range of ages sampled?
Which sampling method was used (opportunity/self-selected samples) tend to be biased and therefore
not representative
R - refers to the extent to which a test or other instrument is consistent in its measures. The
test we used is a well-established psychometric test, so we can say that it is reliable.
A - can you think of why this research is useful? How could these type of findings be used?
V - refers to whether a test is actually measuring what we think it’s measuring. We are using a
shape rotation test to measure spatial ability. This is certainly part of what spatial ability is.
However, how far does it relate to how people use their spatial ability in their everyday life?
The setting was also not a natural one so the study lacks ............................... validity.
A more valid way of measuring people’s spatial ability would be to:
E – what did you consider??