Maya Nelson, Raj S., Genevieve Sigaran, Zoie Tiller
Darwinism is based on five key
observations and inferences:
Species have great fertility. They make more offspring
than can grow to adulthood.
 Populations remain roughly the same size, with modest
fluctuations.
 Food resources are limited, but are relatively constant
most of the time.
From the three observations it must be inferred struggle for
survival must be considered among individuals:
 In sexually reproducing species, generally no two
individuals are identical. Variation is rampant.
 Much of this variation is heritable.

Natural Selection
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The prime motive for all species is to reproduce and survive,
passing on the genetic information of the species from one
generation to the other.
This causes the species to produce more offspring than it can
support. The lack of resources means increased competition for
them. As a consequence some organisms will not survive.
This 'weeding out' of less suited organisms and the reward of
survival to those better suited led Darwin to deduce that
organisms had evolved over time, where the most desirable
characteristics of a species are favored and those organisms
who have them survive to pass their genes on.
Changing environment would mean different characteristics
would be favorable in an environment. Darwin believed that
organisms had 'evolved' to suit their environments.
Descartes claimed to have discovered one fact beyond doubt:
that he is a thinking thing. This famous argument - called the Cogito
after the Latin phrase, “cogito ergo sum” (I think, therefore I am) –
tries to establish the mind as a separate substance from the body.
 The further the mind is taken away from its proper objects – logic
and pure reason – the more likely it is to fall into error. Thus, for
Descartes, the purpose of philosophy is to direct the mind away
from the confusing images of the senses towards the indubitable
truths contained within the mind itself.
 He concluded that the mind was completely separated from the
matter.
 Matter is easily described: it is measurable, has dimensions, can be
touched and seen, sometimes smelt and tasted, divided,
destroyed and altered. Mind, however, can almost be defined as
the opposite. It is invisible, without dimensions, immaterial,
unchanging, indivisible and without limit.

Descartes was a very religious man with a
sincere faith, so he connected his theories
to his beliefs.
 Mind so defined can be equated with the
soul, which in turn can be proven to be
distinct from the body and
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His ideas were based upon the context of the French Revolution,
which was the changing of the Old regime to the new ideals.
Psychology is with Cabanis directly linked on to biology, for
sensibility, the fundamental fact, is the highest grade of life and the
lowest of intelligence. All the intellectual processes are evolved
from sensibility, and sensibility itself is a property of the nervous
system.
The soul is not an entity, but a faculty; thought is the function of
the brain. Just as the stomach and intestines receive food and
digest it, so the brain receives impressions, digests them, and has as
its organic secretion, thought.
He had another theory which contradicted his first, Life is something
added to the organism; over and above the universally diffused
sensibility there is some living and productive power to which we
give the name of Nature.
It’s impossible to avoid ascribing to this power both intelligence
and will. In us this living power constitutes the ego, which is truly
immaterial and immortal.
NATIVISM VS. EMPIRICISM
Two views:
– Nativism: Knowledge is part of our innate
endowment (already “built in” at the time of birth).
– Empiricism: Knowledge comes from
 Plato’s (Socrates’) view:
– At some unconscious level, we know everything
already, but our knowledge is sometimes ‘hidden’.
– Knowledge is innate: It is carried over from an
earlier existence, but forgotten.
– Learning: recollecting (anamnesis)

“PLATO’S PROBLEM”
• How is it possible that native speakers
come to know things (about their
language) in conditions of sparse
evidence?
• In particular, native speakers know things
about their language which:
– they have never been taught;
– they have never experienced

Phineas Gage was a railroad worker who, through a freakish
accident, got a 3-foot-long rod through his head. The rod
went through his left cheek to exited the midline of the skull
anterior to the bregma, resulting in severe injury to his left
and, in all probability, his right prefrontal cortex.
 It was seen as impossible for anyone to survive and at first
Gage was the same. He remembered what happened
before the accident, could immediately walk, and
communicate sensibly.
 Overtime his contractors noticed a difference in his attitude.
He was once an efficient and capable foreman in their
employ previous to his injury but he became fitful, irreverent,
and indulging at times in the grossest profanity (which was
not previously his custom).
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
Gage is an example for the theory of
cerebral localization which described in
detail the focal mapping of the cerebral
function and of how frontal lobe injury can
result in changes of personality that are not
demonstrable by sensory and motor exam.
Paul Broca (1824-1880) was a well-known French surgeonanthropologist-neurologist. Best known for his work on
cerebral cortical localization and speech mechanisms,
Broca also carefully worked out skull and scalp
localization for underlying cortical regions.
 In 1871, Broca treated a man who had sustained a scalp
laceration from a blow to the head without loss of
consciousness or skull fracture. The patient exhibited a not
confluent aphasia about 1 month after injury and
became progressively dulled and eventually lacked
alertness.
 In a post-mortem autopsy Broca found the patient had a
lesion caused by syphilis in the left cerebral hemisphere.
This lesion was determined to cover the area of the brain
important for speech production.
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Dualism was somewhat accepted but did not add up
biologically. Human beings start their lives as entirely
physical or material entities and since nothing outside
of the domain of the physical is added later on in the
course of development, then we must necessarily end
up being fully developed material beings.
Its difficult for the dualist to explain where and why
there could have intervened some non-material, nonphysical event in this process of natural evolution.
Our development can be explained as the
accumulation of matter through the process of
nutrition.
Discoveries from people like Broca and Darwin only
hurt the idea of Dualism.
During the Enlightenment theorists moved
away from such Christian thinking and to
what the world really was made up of
other than what the church told them,
basically to find a way to explain their
existence.
 Dualism was acceptable but as the times
changed materialism became a basis for
thought and scientifically acceptable.
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Natural Selection: Darwin argued that if a
heritable trait contributes to an organism’s
survival or reproductive success, organisms with
that trait should produce more offspring than
those without the trait and that the prevalence
of that trait should gradually increase over
generations.
Controversy of Darwin’s Theory:
› Suggested that the diversity of life is a result of an
unplanned, natural process than that of a divine
creation.
› Implies that humans are NOT unique and that they
share a common ancestry with other species.
Due to the gradual increment nature of
evolution, adaption's sometimes linger in
a population even though they no
longer provide a survival or reproductive
advantage.
 Self Sacrifice explained: W.D. Hamilton
proposed the theory of inclusive fitness.
An organism may contribute to passing
on its genes by sacrificing itself to save
others that share the same genes.

Theorists have focused primarily on the
evolution of physical characteristics in
the animal kingdom but from the very
beginning Darwin recognized the natural
selection was applicable to behavioral
traits.
 Dualism
 Materialism
 Thought and consciousness
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Neurotransmitter are
chemical messengers
that carry signals across
the synapse (junction
between two neurons
where the axon bulb of
one neuron comes in
close proximity with
specialized receptor sites
on another neuron).

Action potential= neural impulses within
the neuron

Neurotransmitters will cause excitation in
the postsynaptic cell (receiving neuron).
› Excitation occurs when the neurotransmitters
make the postsynaptic cell MORE likely to fire
an action potential. When the
neurotransmitter binds with the receptor site,
it causes Na+ to leak into the cell, thus
making the inside of the cell more positive
and closer to the threshold of excitation.
› It depolarizes the postsynaptic cell.

Inhibition: When a neurotransmitter
further polarizes the postsynaptic cell
and it becomes less likely to fire an
action potential.
› The cell is less likely to fire an action
potential.
› Cause chlorine (CL-) to enter the neuron or
potassium K+ to leave the neuron.
Only a sum of the signals moves the
resting potential at the axon the
threshold (-55 mv) will the neuron fire an
action potential.
 Excitation starts actions in the nervous
system. Inhibition is required to slow
down and stuff off certain processes.
 Example: Bend your arm

› Muscles contract= excited
› Muscles relax= inhibited
Neurotransmitters are the brain's chemical
messengers.
 Inhibitory neurotransmitters balance mood
and are affected by excitatory
neurotransmitters, which stimulate the brain.
 Within the two types of neurotransmitters
are chemicals that serve to stabilize mood
and regulate the fight or flight response
associated with anxiety.
 When the neurotransmitters are out of
balance, it can lead to chronic anxiety or
other anxiety disorders.

“Acetylcholine (ACh) is a neurotransmitter
that links motor neurons and muscles. Ach
has an excitatory effect on muscles.
Dopamine, however inhibits muslces and
helps control the voluntary movements.”
 Endorphins= body’s pain relievers
 Diseases due to malfunctioning chemical
messengers:

› Alzheimer’s disease
› Parkinson’s disease
› Schizophrenia
1860s-Paul Broca's discovery that damage
to a specific part of the brain-the left frontal
lobe-was associated with speech
impairment.
 1874-Carl Wernicke identified the part of
the brain responsible for receptive speech
(the upper rear part of the left temporal
lobe),
 1870-Gustav Fritsch and J. L. Hitzig found
that stimulating different parts of the
cerebral cortex produced movement in
different areas of the body.
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Three main parts: brainstem, limbic
system, cerebral cortex.

Brainstem (HINDBRAIN):
contains the
› Medulla - which controls
vital involuntary functions
(breathing), heart rate.
› Pons - involved in
sleeping and arousal.
› Reticular Formationnetwork like group of cells
that filter sensory
information and help
control sleep, arousal and
attention.
Brainstem (HINDBRAIN)= SO IMPORTANT YOU
WOULD DIE WITHOUT IT. NO LIE.
 The medulla sits at the top of the spinal
column at the point where the spinal cord
enters the base of the skull. There are no such
things as MINOR DAMAGES to the medulla, a
“minor damage” can lead to death from
heart or respiratory failure.

› Sneezing, coughing, vomiting, swallowing and
digestion.
The pons is located above the medulla,
where the brainstem bulges inside the skull.
CRUCIAL TO LIFE.
 Plays a role in respiration, consciousness,
sleep, dreaming, facial movement, sensory
processes and the transmission of neural
signals from one part of the brain to another.

› Sensory information coming from the right and left
sides of the brain will have to cross through the
pons before they can move on to other parts of
the brain.
Cerebellum is the large deeply grooved structure
at the base of the brain. NOT AS CRUCIAL TO
SURVIVAL as the medulla and pons.
 It is necessary for the balance of the body,
muscle tone, and performance of motor skills.
Some researches believe it plays a role in
learning motor skills.
 ALCOHOL impairs the functioning of the
cerebellum structure because (in part) it
produces the familiar symptoms of staggering,
clumsiness and slowed reaction time.

The Midbrain structure connects the hindbrain
with the more detailed forebrain. Primarily for
psychologists the most interesting structure is the
Reticular Activating System (RAS). It is located
near the pons, composed of a network of
neurons that extends from the hindbrain regions
into the midbrain.
 It regulates arusal levels in the forebrain, and
takes an important role in sleeping, attention and
consciousness.
 It also is believed by some that it plays a role in
regulating the cardiovascular activity, respiratory
functioning and body movement.
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The forebrain contains several groups of
structures that ultimately works as
subsystems.
› The Limbic system governs emotional and
motivational process.
› The diencephalon contains structures important
to sensory processing and motivation.
› The cerebral cortex is responsibly for cognition
and language.

It is divided into the right and left cerebral
hemispheres.

Limbic System- helps
govern motivation,
emotion and memory.
› Amygdala- linked to fear,
anger and aggression
› Hippocampus- performs a
key function in memory
formation.

Diencephalon
› Hypothalamus- regulates
autonomic nervous system,
emotions and basic drives. It also
serves as a point of connection
between the nervous system and
the endocrine system.
 Interestingly, it can also change
the hormone levels in the bloody
stream by communicating with
the endocrine system.
 Example: If the body needs
water, it “makes” you feel thirsty.
› Thalamus- relay station for sensory
information. Most of the
information our brain collects is
first sent to the thalamus before
being sent to the cortex.

Cerebral Cortex- controls higher-order mental
processes. Composed of two hemispheres and
four lobes.
› It is said to give us our humaness.
1.
2.
3.
Sensory areas specialize in receiving sensory
information. The somatosenory cortex receives
information from the touch receptors in the skin.
Motor Cortex-controls voluntary muscles.
Association Cortex- communicates with the
sensory and motor areas and house higher mental
processes.
Two areas that specialize in language:
1.
1.
2.
Brocas’s area- production of speech
Wernick’s area- involved in language comprehension

Cerebral Cortex

Frontal Lobe- (lies closest to the forehead).
› Broca’s area (production of speech).
› Plays a role in cognitive processes such as
problem solving, judgement, planning and
executing behavior, and certain parts of
personality.
› At the back of the frontal lobe is the motor
cortex (execute motor movements). On the right
side of the brain it affects movement on the left
side of the brain, and vice versa.
› SPECIFIC POINTS along the motor cortex
corresponds to particular points in the body.

Parietal Lobe (not much is known in
comparison)
› Is involved with reading.
› Damages to the parietal lobe is associated with
deficits in reading ability.
› Sensation: a thin strip of the lobe plays a role in
our sense of touch, pressure and pain=
somatosensory cortex (behind the motor cortex).
Specific points along the somatosensory cortex
corresponds to specific particular points in the
body
 Damage to the somatosensory cortex would often
result in numbness of the corresponding body part.

The Montor + Somatosenory Cortex

The Occipital Lobe (located in the very
back of the skull)above the cerebellum.
› Much of the area if responsible for processing
visual information.
 The visual cortex of the occipital lobe is composed
of layers of tissue that contain long axonal fibers.
An action potential is stimulated in specialized cells
of the visual cortex when our eyes see specific
types of visual stimuli.
 Damage to the visual cortex could result in
blindness. Additionally, in some cases of the visual
cortex damaging, blindness may occur even
though the eyes are functioning properly.

Temporal Lobe is in front of the occipital
lobe (behind our ears in side our skull).
› Major function: the processing of auditory
information (aka hearing). The temporal lobe
areas devoted to hearing is called the auditory
cortex.
› The left temporal lobe of most people contains
Wernicke’s area (responsible for the
comprehension of speech).
 Damage to Wernicke’s area results in have
difficulty or cant understand the meaning of
spoken words. They can hear them they just can’t
understand what they mean.

Temporal Lobe is in front of the occipital
lobe (behind our ears in side our skull).
› The inner surfaces of the temporal lobe is
important to the processing of memory. This area
has direct connection to the hippocampus.
› Also believe to play a role in integration of
diverse sensory information.
Communication between the nervous and
endocrine systems occur through the
hypothalamus and its connection with the
pituitary gland(“master” gland that is
responsible for regulating hormones release
in other endocrine glands).

The endocrine system is a chemical system of
communication that relies on the action of specialized
organs called endocrine glands.
 When stimulated, the endocrine glands will release
hormones into the blood stream. The body possess
special receptor sites to “accept” the hormones.
 When the hormone binds to the site: the create a
specific change in the functioning of an organ. In
the heart it can be a change of pace (depending
on the hormone).
 Stimulation created by the hormones last longer
than the that created by action potientals at the
synapse.

Hormones:
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The ovaries and testes are the best known
endocrine glands. They are responsible for
sexuality and reproduction. Ovaries release
estrogens where as testes release
androgens.
The adrenal glands that are located above
the kidneys are important for regulating
arousal and sexual behavior.

The adrenal medulla (inside of the Adrenal Gland)
releases nor epinephrine and epinephrine (adrenaline)
when the nervous system becomes active during times
of stress.

When they (nor epinephrine and
epinephrine) are released in the body
OUTSIDE of the central nervous systems they
act as hormones. Then due to the sudden
flooding of the bloodstreams with these
hormones, the heart rate, blood pressure
and respiration increases.

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The adrenal cortex (found externally on the adrenal glands)
produces adrenal androgens which are male sex hormones
found in both males and females.
Thyroid gland located in the throat, presides over important
aspects of metabolism.

Malfunctioning of the thyroid can lead to
serious physical symptoms.
 Hyperthyroidism (over active)= increased
metabolism, weight loss, bulging eyes,
weakness, cardiac problems.
 Hypothyroidism (underactive)= lowered
metabolism, obesity, menstrual abnormalities
in females and depression. They often copy
that of depressive psychological disorders.
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Biological rhythms are the periodic
fluctuations in physiological functioning.
The Circadian rhythms are the 24 hour
biological cycles found in humans (and
other species).
›
Regulation of sleep, blood pressure, urine
production, hormonal secretions, alertness, short
term memory ,etc.
“Biological Clock”

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The Suprachiasmatic SCN
nucleus (group of cells) in
the hypothalamus receives
information about
illumination through the eyes
and to the retina.
The SCN takes the
information on the lengths of
the day and night from the
retina, interprets it and
moves it to the pineal gland.
Which secrets melatonin (a
hormone). The secretion of
this hormone peaks at night
and recedes during the day.

Phases Markers of the Circadian rhythm:
›
›
Melatonin secretion by pineal gland.
Core body temperature [Research shows that
people fall asleep as their body temperatures
rises and falls.]

Circadian rhythm disorders…
 Jet Lag
 Shift work sleep disorder (people who work
nights/rotating shifts)
 Delayed sleep phase syndrome- much later than
“normal” timing of sleep onset and offset; peak of
alertness in the middle of the night.
 Advanced sleep phase syndrome- difficulty staying
awake in the evening and staying asleep in the
morning.
 Irregular sleep-wake rhythm- sleeping at irregular
times; more that one per day (waking up frequently
during the night and naps during the day).
 Non-2-4-hour-sleep-wake syndrome- affected the
individual’s sleep occurs later and later each day;
period of peak alertness continuously moves around
the clock from day to day.
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Correlational studies are used to look for
relationships between variables.
There are three possible results of a correlational
study:
› a positive correlation
› a negative correlation
› no correlation
The correlation coefficient is a measure of
correlation strength and can range from –1.00 to
+1.00.
Positive Correlations: Both variables
increase or decrease at the same time. A
correlation coefficient close to +1.00
indicates a strong positive correlation.
 Negative Correlations: Indicates that as the
amount of one variable increases, the other
decreases (and vice versa). A correlation
coefficient close to -1.00 indicates a strong
negative correlation.
 No Correlation: Indicates no relationship
between the two variables. A correlation
coefficient of 0 indicates no correlation.
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While correlational studies can suggest
that there is a relationship between two
variables, they cannot prove that one
variable causes a change in another
variable.
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1. Naturalistic Observation
› Naturalistic observation involves observing and
recording the variables of interest in the natural
environment without interference or
manipulation by the experimenter
Advantages of Naturalistic Observation
› Gives the experimenter the opportunity to view
the variable of interest in a natural setting.
› May be the only option if lab experimentation is
not possible.
› Can offer ideas for further research.

Disadvantages of Naturalistic Observation
› Can be time consuming and expensive.
› Does not allow for scientific control of variables.
› Experimenters cannot control extraneous
variables.
› Subjects may be aware of the observer and
may act differently as a result.

The Survey Method
› In this method, a random sample of participants
completes a survey, test, or questionnaire that
relates to the variables of interest.
› Random sampling is a vital part of ensuring the
generalizability of the survey results.

Advantages of the Survey Method
› It’s fast, cheap, and easy. Researchers can
collect large amount of data in a relatively short
amount of time.
› More flexible than some other methods.

Disadvantages of the Survey Method
› Can be affected by an unrepresentative
sample or poor survey questions
› Participants can affect the outcome.
Some participants try to please the
researcher, lie to make themselves look
better, or have mistaken memories.


3. Archival Research
› Archival research is performed by analyzing
studies conducted by other researchers or by
looking at historical patient records.
Advantages of Archival Research
› The experimenter cannot introduce changes in
participant behavior.
› Enormous amounts of data provide a better view of
trends, relationships, and outcomes
› Often less expensive than other study methods.
Researchers can often access data through free archives
or records databases.

Disadvantages of Archival Research
› The researchers have not control over how
data was collected.
› Important date may be missing from the
records
› Previous research may be unreliable

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
A study is referred to as double-blind if both the
researcher and the participants are not aware of
which treatment each participant is receiving.
Ex: “a placebo is usually given to half the
participants and the actual medication of interest
to the remaining participants. In a double-blind
experiment, neither the researchers nor the
participants know who received the placebo and
who received the medication. “
Double-blind studies are conducted to prevent
bias on the part of the researchers and the
participants.
Test under controlled conditions where one
variable is manipulated to find out its effect
on the dependent variable.
 Four Types

› Laboratory experiments
› Field experiments
› Quasi experiments: these are experiments in
which the researcher does NOT randomly
allocate the participants to the conditions.
› Natural experiments :psychologists take
advantage of a naturally occurring event


Advantages
› The experimenter has control over variables
› Experiments are reliable – the procedure is standardized and
therefore replicable
› It is the only method that determines cause and effect
› Accurate recordings can be made
Disadvantages
› Laboratory experiments may lack ecological validity. As the
setting is artificial, the behavior of participants may be unnatural
and the findings may not be generalized to other settings.
› The independent and dependent variables tend to be very
narrow and specific. Psychologists have squeezed the study of
human life into a laboratory setting to the extent that it is
different from the natural setting.



This is an experiment carried out in the natural environment or setting
whilst the independent variable is still manipulated by the experimenter.
Advantages
› Field experiments are higher in ecological validity as the research is
conducted in a natural setting. Behavior is likely to be relatively
unaffected compared with an experiment conducted in a
laboratory.
› Field experiments are higher in ecological validity as the research is
conducted in a natural setting. Behavior is likely to be relatively
unaffected compared with an experiment conducted in a
laboratory.
› The researcher still manipulates the independent variable
› They are reliable – structured using a standardized procedure and
therefore replicable
Disadvantages
› Compared to a laboratory experiment, field experiments do not
have the same amount of control
› They are time consuming and expensive
› Field experiments raise serious ethical issues – it is almost impossible to
give informed consent in these experiments

Pavlov’s Dog
› Classical conditioning is one of the major topics studied by
students in every introductory psychology class. You may be
surprised to learn that it was actually a physiologist who made
this important psychological discovery. The Asch Conformity
Experiment
Asch Conformity Experiment
› Researchers have long been interested in the degree to which
people follow or rebel against social norms. During the 1950s,
psychologist Solomon Asch conducted a series of experiments
designed to demonstrate the powers of conformity in groups.
 The Stanford Prison Experiment
› Philip Zimbardo's famous experiment cast regular students in the
roles of prisoners and prison guards. While the study was originally
slated to last two weeks, it had to be halted after just six days
because the guards became abusive and the prisoners began
to show signs of extreme stress and anxiety


A conversation, such as one conducted by a reporter, in which
facts or statements are elicited from another.

Two Types
› Formal (structured) which use a questionnaire
› Informal (unstructured) – interviewee talks freely

Ex: A researcher will ask a series of questions in which you must
answer. Some questions that could be asked are…
› Is there a history of mental illness in your family?
› Have you ever been prescribed medication for bi-polar
disorder?
› How old are you?
› What is your daily schedule like?
› Have you ever thought about suicide?
› When was the last time you engaged in sexual activity?

Advantages
› High in VALIDITY – the interview should
measure what it claims to measure, and
the responses should give a true and
accurate picture. Their flexibility enables
the clarification of meanings
› Qualitative data – the responses provide
insights about peoples’ feelings, attitudes,
beliefs, opinions – about the experience
of being a human being. They may yield
hypotheses for testing
› Primary source of data
› Cooperation of the interviewee

Disadvantages
› Lack reliability – reliability refers to structure. An
unstructured interview lacks structure – it is not consistent,
trustworthy in terms of procedure; it is not replicable
› Interviewer bias – the characteristics of the researcher,
such as age, sex, race, may affect the responses. The
greater the status differences e.g. young interviewer/old
interviewee, the greater the effect on the results. LABOV
found that black children would not talk to white
interviewers and this was interpreted as black children
being unintelligent. Labov also found that if interviewers
got down to the same level as children, the children
would speak much more.
› Interviewer bias – leading. Leading refers to how the
interviewer might guide the responses of an
interviewee. Leading may be effected verbally by the
actual words used, and by the use of paralanguage –
pitch and tone of voice. Leading may also be effected
non-verbally by body language, by nods and gestures
› Time consuming, expensive




A case study is an in-depth study of one person.
In a case study, nearly every aspect of the
subject’s life and history is analyzed to seek
patterns and causes for behavior.
The hope is that learning gained from studying one
case can be generalized to many others.
Unfortunately, case studies tend to be highly
subjective and it is difficult to generalize results to a
larger population.
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Common sets of questions set out on paper or the internet
There are two types of questionnaires
› OPEN ENDED – a respondent may talk freely – qualitative data
› FIXED CHOICE – a respondent is given options to select – tick box
– quantitative data
 Advantages
› RELIABILITY – this refers to consistency, trustworthy. As the
procedure is standardized, it is high in reliability. Everyone
receives the same questions in the same order and this ensures
consistency
› LARGE NUMBERS mean that the sample is likely to be
REPRESENTATIVE – ALIKE THE TARGET POPULATION IN EVERY
IMPORTANT RESPECT
› Reach a wide geographical area – sample is more likely to be
representative
› Simple quick and easy to use – participants understand what is
required of them

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Disadvantages
› Lack VALIDITY – with regard to method, it should measure
what it claims to measure and with regard to data, it
should provide a true and accurate picture. In the case
of questionnaires, memories could be faulty, LaPiere noted
that what people say and what people do are two very
different things, and people may mislead – be deceitful
› NON-RESPONSE – many people fail to answer
questionnaires and this may be significant if NON
RESPONDENTS DIFFER SIGNIFICANTLY FROM THOSE WHO
DO RESPOND
› Pre-determined questions means that important
assumptions about the phenomenon being investigated
have already been made.
• Nature vs. Nurture:
• Researchers focus on twin studies. Twin studies
compare specific traits between pairs of
identical twins (100% of their genetic code) and
fraternal twins (no more genetically related that
other siblings.
• If identical twins have similar traits more than
then fraternal twins do, a genetic basis for the
trait is implied. HOWEVER, if identical twins and
fraternal twins do no differ in similarities there is
less support for the existence of genetic
influence on trait.
• Identical twins in different environments?
• Identical twins in same environment