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Methods and techniques in psychology:

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Methods and techniques in psychology: Why is psychology a science? – PowerPoint PPT presentation

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Title: Methods and techniques in psychology:


1
Methods and techniques in psychology
2
  • Why is psychology a science?
  • "Science" involves using the scientific method
  • Testable (falsifiable) hypotheses and theories
    (hence precise operational definitions of
    phenomena).
  • Empirically-obtained, publicly-available and
    replicable data (hence usually quantitative
    measurements).
  • Identification of causal relationships.
  • Parsimony ("Occam's razor").
  • Healthy scepticism.
  • Objectives of science
  • Description, Explanation, Prediction.

3
  • Science versus pseudoscience

Science Pseudoscience
Evidence-based Based on appeals to authority, e.g. "wisdom of the ancients"
Claims open to scrutiny and refutable Adherents protect claims from disproof
All evidence is considered,for and against claims Only apparently-corroborative evidence is considered
Observable, replicable phenomena Phenomena often unreplicable
Scepticism encouraged Scepticism discouraged
Parsimonious, and consistent with existing science Non-parsimonious, often inconsistent with existing science
Develops over time Static
4
  • Objectivity the need for operational
    definitions
  • Many psychological phenomena are poorly defined
    and/or have "folk psychology" definitions
  • e.g. play, aggression, anxiety, arousal, fatigue,
    frustration, intelligence.
  • Operational definitions are in terms of the
    processes needed to measure the phenomenon.
  • e.g. "social play" "wrestling behaviour between
    two young animals, accompanied by 'play signals'
    (exaggerated gait, inhibited biting) and
    unaccompanied by deliberate infliction of injury
    by either participant".

5
  • Definition of autism
  • DSM IV DIAGNOSTIC CRITERIA FOR AUTISTIC
    DISORDER A. A total of six (or more) items from
    (1), (2), and (3), with at least two from (1),
    and one each from (2) and (3) 1. Qualitative
    impairment in social interaction, as manifested
    by at least two of the following a) marked
    impairments in the use of multiple nonverbal
    behaviors such as eye-to-eye gaze, facial
    expression, body posture, and gestures to
    regulate social interaction. b) failure to
    develop peer relationships appropriate to
    developmental level. c) a lack of spontaneous
    seeking to share enjoyment, interests, or
    achievements with other people,
  • (e.g., by a lack of showing, bringing, or
    pointing out objects of interest to other
    people). d) lack of social or emotional
    reciprocity (e.g. not actively participating in
    simple social play or games, preferring solitary
    activities, or involving others in activities
    only as tools or "mechanical" aids).
  • 2. Qualitative impairments in communication as
    manifested by at least one of the following a)
    delay in, or total lack of, the development of
    spoken language (unaccompanied by an attempt to
    compensate through alternative modes of
    communication such as gesture or mime). b) in
    individuals with adequate speech, marked
    impairment in the ability to initiate or sustain
    a conversation with others. c) stereotyped and
    repetitive use of language or idiosyncratic
    language. d) lack of varied, spontaneous
    make-believe play or social imitative play
    appropriate to developmental level.
  • 3. Restricted repetitive and stereotyped patterns
    of behavior, interests and activities, as
    manifested by at least two of the following a)
    encompassing preoccupation with one or more
    stereotyped and restricted patterns of interest
    that is abnormal either in intensity or focus. b)
    apparently inflexible adherence to specific,
    nonfunctional routines or rituals. c) stereotyped
    and repetitive motor mannerisms (e.g hand or
    finger flapping or twisting, or complex
    whole-body movements). d) persistent
    preoccupation with parts of objects.
  • B. Delays or abnormal functioning in at least
    one of the following areas, with onset prior to
    age 3 years (1) social interaction. (2) language
    as used in social communication. (3) symbolic or
    imaginative play.
  • C. The disturbance is not better accounted for
    by Rett's Disorder or Childhood Disintegrative
    Disorder.

6
  • Objectivity the need for precise measurement
  • Independent variable - the thing you manipulate,
    as an experimenter.
  • Dependent variable - the thing you measure.
  • e.g. effects of status on initial interaction
    distance (Dean, Willis and Hewitt 1975)
  • IV status - operational definition military
    rank
  • DV interaction distance - operational defnition
    number of floor squares between interactors
    (various settings, all with standard floor-tile
    size)
  • Inter-observer reliability checked
  • Results status affected interpersonal distance
    initial distance was higher when a lower-rank
    person approached a higher-rank person, than when
    peers met or a higher-rank person approached a
    lower-rank person

7
  • Objectivity the need to avoid experimenter
    effects
  • Huge literature on how experimenters can bias
    results (Rosenthal 1966).
  • Ways to minimise these effects
  • Precise definitions of IV's and DV's.
  • Standardised instructions and procedures.
  • Double-blind techniques.
  • Independent replication.

8
  • Theories and data
  • Theories integrate and summarise scientific
    facts.
  • Give rise to hypotheses - specific predictions.
  • Interaction between theory and observation
  • theory guides observation, observation modifies
    theory

mental activity affects brain health
theory
listening to Beyoncé rots your brain
hypothesis
(a) study Beyoncé fans, or (b) experiment -
listeners vs non-listeners
test (observation, experiment)
revise theory
hypothesis
only long periods of exposure have ill-effects
test (observation, experiment)
prolonged mental activity affects brain health
9
  • History of psychology
  • 19th c. introspective methods - results open to
    dispute.
  • Early 20th c. Behaviourism - restriction to
    purely behavioural measures that are amenable to
    quantitative analysis.
  • Late 20th c. behavioural data used as an
    indirect measure of unobservable internal states
    (e.g. RT as an index of processing speed in
    cognitive psychology).

10
  • History of neuropsychology
  • 19th c. detailed qualitative single-patient case
    studies.
  • Problem - results open to different
    interpretations.
  • Early 20th c. quantitative group studies.
  • Problem - group performance does not necessarily
    reflect individual performance.
  • Late 20th c. detailed quantitative
    single-patient case studies. Descriptions of
    patients supported by quantitative data (plus
    statistical comparisons of patient to group
    norms).

11
  • Tinbergen (1963) four "whys"
  • Ultimate and proximate causes of behaviour.
  • 1. Function (adaptation ultimate cause)
  • 2. Causation (proximate cause)
  • 3. Ontogeny (development proximate cause)
  • 4. Phylogeny (evolutionary history ultimate
    cause)
  • e.g. Why do starlings sing? (1) To attract mates
    to breed. (2) Increasing day-length affects
    hormone levels. (3) They learn to sing from their
    neighbours. (4) Song has evolved from simpler
    songs in ancestral bird species.
  • Psychology has traditionally focused on 2 and 3,
    neglecting 1 and 4.

12
  • Methods used in psychology

Advantages Disadvantages
Observation Naturalistic behaviour. Time-consuming. Unlikely to reveal causal relationships.
Interviews, Case Studies and Questionnaires In-depth, detailed information. Reporting bias. Lack of self-insight.
Experiments Best way to establish causal relationships Data sometimes too closely tied to theory. Artificial (ecological validity) Participant representativeness.
13
  • is it safe to use a mobile phone while driving?

Advantages Disadvantages
Observation (accident statistics) Information on real-world risks. Accidents involving phones are rare (Violanti 1998 5 users out of sample of 223,137 accidents !
Interviews, Case Studies and Questionnaires In-depth, detailed information. Reporting bias (Chapman and Underwood 2000 80 of near-accidents forgotten within 2 weeks).
Experiments Best way to establish how phone-use might increase risk of accident. Simulators cannot simulate real risks of driving real-world studies are unethical. Artificial tasks, in terms of content and timing of conversation. Participants often unrepresentative.
14
  • Problems with correlational techniques
  • Does smoking cause cancer?
  • Strong correlation between smoking and cancer
    -but does smoking cause cancer?
  • Alternative explanations
  • Cancer-prone people are attracted to smoking.
  • Stress causes people to smoke and to develop
    cancer.
  • Correlations usually have too many alternative
    explanations.

15
  • The experimental method is the best way of
    identifying causal relationships.
  • X causes Y if
  • X occurs before Y
  • Y happens in the presence of X
  • Y does not happen in the absence of X

16
The "Mozart Effect" babies that listen to Mozart
before birth are supposedly more intelligent as
children. X (listening to Mozart) is associated
with Y (intelligence). What causes the change in
intelligence? To demonstrate a causal
relationship, need to show that (a) listening to
Mozart precedes the change in intelligence (X
precedes Y) (b) the change in intelligence
occurs when babies listen to Mozart (Y happens in
presence of X) (c) the change in intelligence
does not occur when babies do not listen to
Mozart (Y does not happen without X i.e. other
explanations can be ruled out).
17
Alternative explanations for the Mozart
effect 1. Listening to Mozart directly affects
intellligence by stimulating neural
development. 2. Babies who listen to Mozart have
better - educated parents (more interested in
their children's development and education). 3.
Babies who listen to Mozart have better -
educated parents (wealthier and therefore
healthier). 3. Mothers who listen to Mozart are
more relaxed somehow this affects the baby's
neural development. 4. Babies who listen to
Mozart are more relaxed somehow this affects
their neural development.
18
Good experimental designs enable us to eliminate
some of these alternative explanations To
establish causality we use groups that differ
systematically only on one variable (the
independent variable) and measure the effects of
this on an outcome variable (the dependent
variable).
Pick pregnant women who do not differ
systematically on any variables (age, musical
preferences, SES, health, etc.).
Randomly assign half to listen to Mozart, and
half to listening to something else.
Measure the children's intelligence systematic
differences between groups are probably due to
the mothers' different experiences (i.e. Mozart/
no Mozart).
19
Experiment to test the Mozart effect
The ONLY systematic variation between
experimental and control groups is exposure to
Mozart worrying, happiness, motivation,
irritability, etc. vary randomly
(unsystematically) between groups
20
Why do we use statistics? Most studies compare
groups - Behaviour often shows variability hence
individual performance may be atypical. Individual
s in a group vary randomly around "average"
performance. Compare average of one group to
average of another.
21
Why do we use statistics? Exceptions -
Behaviourist studies. Psychophysical studies.
High degree of control over behaviour reduces
variability and enhances replicability of
findings.
Typical patterns of lever-pressing in response to
different schedules of reinforcement
22
The kinetic depth effect
Effects of frame-to-frame distance between dots
on perception of depth
23
Disadvantages of the experimental
method Intrusive - participants know they are
being observed, and this may affect their
behaviour. Experimenter effects. Not all
phenomena are amenable to experimentation, for
practical or ethical reasons (e.g. post-traumatic
stress disorder, near-death experiences, effects
of physical and social deprivation, etc.) Some
phenomena (e.g. personality, age or sex
differences) can only be investigated by methods
which are, strictly speaking, quasi-experimental.
24
Conclusion Experiments are a useful tool for
establishing cause and effect - but other methods
(e.g. observation) are also important in
science. A good experimental design ensures that
the only variable that varies is the independent
variable chosen by the experimenter - the effects
of alternative confounding variables are
eliminated (or at least rendered unsystematic by
randomisation). "Science" is mainly defined not
by what you study, but by how you study it.
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