Due Monday by 8:30pm Introduction to Abnormal Psychology

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Chapter Four

The Scientific Method in Abnormal Psychology

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The Scientific Method in Clinical Research

  • Replication:
  • Results must be repeated in multiple studies to reduce the chance of findings due to experimenter bias, methodological flaws, or sampling errors
  • Scientific method:
  • Provides systematic collection of data, controlled observation, and the testing of hypotheses

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The Scientific Method in Clinical Research (cont’d.)

  • Hypothesis:
  • Conjectural statement that usually describes a relationship between two variables
  • Theory:
  • Group of principles and hypotheses that together explain some aspect of a particular area of inquiry

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Characteristics of Clinical Research

  • Clear, systematic statement of hypotheses
  • Potential for self-correction
  • Hypothesize the relationship between variables
  • Operational definition:
  • Clearly stated definition of variable studied

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Characteristics of Clinical Research (cont’d.)

  • Reliability:
  • The degree to which a measure or procedure repeatedly yields the same results
  • Validity:
  • Measuring what is intended to be measured
  • Base rates:
  • The rates of natural occurrence of phenomena in the population being studied

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Characteristics of Clinical Research (cont’d.)

  • Statistical significance:
  • The likelihood that a relationship is not due to chance alone
  • Clinical significance:
  • Whether a statistically significant finding is meaningful

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Experiments

  • Experiments:
  • Perhaps best tool for testing cause-and-effect relationships
  • In its simplest form, an experiment has three parts:
  • Experimental hypothesis
  • Independent variable
  • Dependent variable

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Experiments (cont’d.)

  • Experimental hypothesis:
  • Prediction concerning how an independent variable will affect dependent variable
  • Independent variable:
  • (Possible cause) experimenter manipulates to determine effect on dependent variable
  • Dependent variable:
  • Expected to change as a result of changes in independent variable

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Experiments (cont’d.)

  • Two primary concerns of any experiment:
  • Eliminating extraneous or confounding variables promotes internal validity
  • Internal validity:
  • A high degree of certainty that change to dependent variable is due to an independent variable
  • Making sure results extend beyond experiment
  • External validity:
  • Findings can generalize to other groups or conditions

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Experiments (cont’d.)

  • Experimental group:
  • Subjected to independent variable
  • Control group:
  • Similar in every way to experimental group except not subjected to manipulation of independent variable
  • Placebo control:
  • Induces expectancy without actual treatment (no manipulation at all)

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Experiments (cont’d.)

  • Additional concerns in clinical research:
  • Placebo group can also show significant improvements
  • Participants may “guess” correctly that they are receiving placebo treatment, thereby reducing expectancy effects
  • Elimination of strong responders to placebo
  • Experimenter or participant expectations can also influence outcomes of studies

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Experiments (cont’d.)

  • Blind design:
  • Those helping with the study are not aware of research
  • Reduces impact of experimenter expectations
  • Double-blind design:
  • Neither participants nor experimenters are aware of experimental conditions
  • Reduces impact of experimenter and participant expectations

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Correlations

  • Correlation:
  • Extent to which variations in one variable are accompanied by increases or decreases in second variable
  • Variables are not manipulated
  • Statistical analysis is preformed to determine whether there is a relationship between the variables

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Correlations (cont’d.)

  • Correlation coefficient:
  • Symbolized by symbol r
  • Expresses relationship between variables
  • Has a numerical value between –1 and +1
  • Correlations indicate the degree to which two variables are related, not the reason for the relationship

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Correlations (cont’d.)

  • Positive correlation:
  • Increase in one variable accompanied by increase in the other
  • Negative correlation:
  • Increase in one variable accompanied by decrease in the other

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Correlations (cont’d.)

Figure 4-2 Possible Correlation Between Two Variables The more closely the data points approximate a straight line, the greater the magnitude of the correlation coefficient r. The slope of the regression line rising from left to right in example (a) indicates a perfect positive correlation between two variables, whereas example (b) reveals a perfect negative correlation. Example (c) shows no correlation whatsoever.

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Analogue Studies

  • Replicate or simulate real-life situations under controlled conditions
  • Used when not possible to control all variables in real-life situations
  • Advantage: allows study of phenomenon using experimental designs that are not possible with correlation studies

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Field Studies

  • Behaviors and events are observed and recorded in their natural environment
  • Employs data collection techniques (interviews, questionnaires, etc.)
  • Observers must be highly trained and must avoid disrupting behavioral processes being observed
  • Can be used to examine mass behavior after traumatic events

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Field Studies (cont’d.)

  • Limitations:
  • Determining causality is difficult
  • Many factors affecting real-life situations makes it impossible to control and distinguish all possible variables (difficult to interpret)
  • Observer can never be sure presence didn’t influence result

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Single-Participant Studies

  • Idiographic (in depth study of one person) rather than nomothetic orientation (study of large numbers of people)
  • Two types of single-participant studies:
  • Case study
  • Single-participant experiment

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Single-Participant Studies (cont’d.)

  • Case study:
  • Intensive study of one individual that relies on clinical data, such as observations, psychological tests, historical, and bibliographic information
  • Helpful in determining diagnosis, characteristics, course, and outcome of complicated disorder

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Single-Participant Studies (cont’d.)

  • Single-participant experiment:
  • Some aspect of a person’s behavior is used as a control/baseline for comparison with future behaviors
  • Multiple-baseline study:
  • Baselines on two or more behaviors or the same behavior in two or more settings are obtained prior to intervention

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Single-Participant Studies (cont’d.)

Figure 4-3 A Multiple-Baseline Study The figures show the percentage of time Bob and a non-Asperger peer spent behaving appropriately during cooperative learning, recess, and lunch. During baseline, the percentage of time Bob displayed appropriate behaviors in cooperative learning, recess, and lunch was under 10 percent. With the SODA intervention, the percentage increased to about 70 percent during cooperative learning and recess and to more than 40 percent during lunch. At a five-month follow-up, it was found that the gains in appropriate behaviors were maintained.

Source: From Bock (2007, p.92)

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Biological Research Strategies

  • Genetics and epigenetics:
  • Focus on influence of specific genes in development of psychopathology
  • Epigenetics: shedding light on how the environment influences gene expression
  • Genetic linkage studies:
  • Attempts to determine whether a disorder follows a genetic pattern

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Biological Research Strategies (cont’d.)

  • Endophenotypes:
  • Measurable characteristics (neurochemical, cognitive, etc.) that can give clues regarding the genetic pathways involved in a disorder
  • Can be inherited
  • Are seen even in family members who do not have the disorder
  • Occur more frequently in affected families than in the general population

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Other Concepts in Biological Research

  • Latrogenic effects:
  • Are unintended effects of therapy
  • Penetrance:
  • Degree to which a genetic characteristic is manifested by individuals carrying specific genes associated with it

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Other Concepts in Biological Research (cont’d.)

  • Biological challenge tests:
  • Used to determine effect of a substance on behavior
  • Animal models:
  • Allow for control of variables studied
  • Allow analysis across multiple generations
  • Permit experimental procedures that would not be practical to use with humans

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Epidemiological and Other Forms of Research

  • Some information-producing strategies:
  • Survey research
  • Longitudinal research
  • Historical research
  • Twin studies
  • Treatment outcome studies
  • Treatment process studies
  • Program evaluation

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Epidemiological and Other Forms of Research (cont’d.)

  • Epidemiological research:
  • Examines the rate and distribution of mental disorders in the population
  • Prevalence rates:
  • Percentage of individuals in targeted population with a particular disorder during a specific period of time
  • Incidence rate:
  • Number of new cases of a disorder that appear in an identified population within a specific period of time

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