Research in Abnormal Psychology

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Chapter 2

• Research in Abnormal Psychology

Slides Handouts by Karen Clay Rhines,
Ph.D. Seton Hall University
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Research in Abnormal Psychology

• Research is the key to accuracy in all fields
• Particularly important (and challenging) in the
  field of abnormal psychology
• Theories and treatments that seem reasonable and
  effective in individual instances may prove
  disastrous when widely applied
• Only after rigorous testing can a theory or
  technique be considered valid or effective

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Research in Abnormal Psychology

• Clinical researchers face certain challenges that
  make their investigations particularly difficult
• Measuring unconscious motives
• Assessing private thoughts
• Monitoring mood changes
• Clinical researchers must consider the cultural
  backgrounds, races, and genders of those they
  study
• Clinical researchers must follow the code of
  ethics to ensure that their subjects are not
  harmed

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What Do Clinical Researchers Do?

• Clinical researchers try to discover laws and
  principles of abnormal psychological functioning
• Generally do not assess, diagnose, or treat
  individual clients
• Search for nomothetic understanding
• General or universal laws
• Use the scientific method to pinpoint
  relationships among variables
• Use three methods of investigation

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The Case Study

• Provides a detailed description of a persons
  life psychological problems
• Is helpful because it can serve as a source of
  new ideas about behavior
• Freuds theories based entirely on case studies
• May offer tentative support for a theory
• May challenge a theorys assumptions
• May inspire new therapeutic techniques
• May offer opportunities to study unusual problems

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The Case Study

• Has limitations
• Observers are biased
• Relies on subjective evidence
• Is low on internal validity
• Provides little basis for generalization
• Is low on external validity
• These limitations are addressed by the two other
  methods of investigation

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The Correlational Method the Experimental
Method

• Do not offer richness of detail
• Allow researchers to draw broad conclusions
• Typically involve observing many individuals
• Researchers apply procedures uniformly
• Studies can be replicated
• Researchers use statistical tests to analyze
  results

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The Correlational Method

• Correlation is the degree to which events or
  characteristics vary from each other
• Measures the strength of a relationship
• Does not imply cause and effect
• The people chosen for a study are its subjects or
  participants, collectively called a sample
• The sample must be representative

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The Correlational Method

• Correlational data can be graphed and a line of
  best fit can be drawn
• Positive correlation variables change in the
  same direction

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Positive Correlation
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The Correlational Method

• Correlational data can be graphed and a line of
  best fit can be drawn
• Negative correlation variables change in the
  opposite direction

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Negative Correlation
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The Correlational Method

• Correlational data can be graphed and a line of
  best fit can be drawn
• Unrelated no consistent relationship

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No Correlation
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The Correlational Method

• The magnitude (strength) of a correlation is also
  important
• High magnitude variables which vary closely
  together fall close to the line of best fit
• Low magnitude variables which do not vary as
  closely together loosely scattered around the
  line of best fit

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High (Positive) Correlation
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Moderate (Positive) Correlation
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The Correlational Method

• Direction and magnitude of a correlation are
  often calculated statistically
• Called the correlation coefficient, symbolized
  by the letter r
• Sign ( or -) indicates direction
• Number (from 0.00 to 1.00) indicates magnitude
• 0.00 no consistent relationship
• 1.00 perfect positive correlation
• -1.00 perfect negative correlation
• Most correlations found in psychological research
  fall far short of perfect

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The Correlational Method

• Correlations can be trusted based on statistical
  probability
• Statistical significance means that the finding
  is unlikely to have occurred by chance
• By convention, if there is less than a 5
  probability that findings are due to chance (p lt
  0.05), results are considered significant and
  thought to reflect the larger population
• Generally, confidence increases with the size of
  the sample and the magnitude of the correlation

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The Correlational Method

• Advantages of correlational studies
• Have high external validity
• Can generalize findings
• Can repeat (replicate) studies on other samples
• Difficulties with correlational studies
• Lack internal validity
• Results describe but do not explain a relationship

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The Correlational Method

• Two special forms of correlational study
• Epidemiological studies
• Reveal the incidence and prevalence of a disorder
  in a particular population
• Incidence number of new cases in a given time
  period
• Prevalence total number of cases in a given
  time period
• Longitudinal studies
• Observe one sample of participants on many
  occasions over a long period of time

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The Experimental Method

• An experiment is a research procedure in which a
  variable is manipulated and the manipulations
  effect on another variable is observed
• Manipulated variable independent variable
• Variable being observed dependent variable
• Allows researchers to ask such questions as Does
  therapy X reduce symptoms of disorder Y?
• Causal relationships can only be determined
  through experiments

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The Experimental Method

• Statistics and research design are very important
• Researchers must eliminate all confounds those
  variables other than the independent variable
  that may also be affecting the dependent variable
• Three features are included in experiments to
  guard against confounds
• The control group
• Random assignment
• Blind design

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The Experimental Method

• A control group is a group of participants who
  are not exposed to the independent variable, but
  whose experience is similar to that of the
  experimental group
• By comparing the groups, researchers can better
  determine the effect of the independent variable
• Rules of statistical significance are applied

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The Experimental Method

• Researchers must also watch out for preexisting
  differences between the experimental and control
  groups
• To do so, researchers use random assignment
  any one of a number of selection procedures that
  ensures that every participant in the experiment
  is as likely to be placed in one group as another
• Examples coin flip drawing names from a hat

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The Experimental Method

• A final problem with confounds is bias
• To avoid bias by the participant, experimenters
  employ a blind design, in which participants
  are kept from knowing what condition of the study
  (experimental or control) they are in
• One strategy for this is providing a placebo
  something that looks or tastes like real therapy
  but has no key ingredient
• To avoid bias by the experimenter, experimenters
  employ a double-blind design, in which both
  experimenters and participants are kept from
  knowing what condition of the study participants
  are in
• Often used in medication trials

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Alternative Experimental Designs

• It is difficult to devise an experiment that is
  both well controlled and enlightening
• Clinical researchers often must settle for
  designs that are less than ideal and include
• Quasi-experimental designs
• Natural experiments
• Analogue experiments
• Single-subject experiments

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Alternative Experimental Designs

• In quasi-experimental designs, investigators do
  not randomly assign subjects to groups, but make
  use of group that already exist
• Example children with a history of child abuse
• To address the problem of confounds, researchers
  use matched control groups
• These groups are matched to the experimental
  group, based on demographic and other variables

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Alternative Experimental Designs

• In natural experiments, nature manipulates the
  independent variable and the experimenter
  observes the effects
• Example psychological impact of flooding
• Cannot be replicated at will
• Broad generalizations cannot be made

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Alternative Experimental Designs

• Analogue experiments allow investigators to
  freely manipulate independent variables while
  avoiding ethical and practical limitations
• They induce laboratory subjects to behave in ways
  that seem to resemble real life
• Example animal subjects
• Major limitation of all analogue research is that
  experimenters cannot be certain that the
  phenomena observed in the lab are the same as the
  psychological disorders being investigated

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Alternative Experimental Designs

• In a single-subject (n of 1) experiment, a
  single participant is observed both before and
  after manipulation of an independent variable
• Experiments rely on baseline data to set a
  standard for comparison
• Common experimental designs are ABAB and
  multiple-baseline designs

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Alternative Experimental Designs

• In ABAB (reversal) designs, a participants
  reactions are measured during a baseline period
  (A), after the introduction of the independent
  variable (B), after the removal of the
  independent variable (A), and after
  reintroduction of the independent variable (B)
• The subject is, essentially, compared against him
  or herself rather than against control subjects

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Alternative Experimental Designs

• Multiple-baseline designs examine two or more
  dependent variables for change when an
  independent variable is introduced

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Alternative Experimental Designs

• Both types of single-subject experiments are
  similar to individual case studies
• Both focus on one subject only
• Both have low external validity
• However, both types of single-subject experiments
  have higher internal validity than the case
  study, given the manipulation of an independent
  variable

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