1. Comer, Abnormal Psychology, 6e – Chapter 2 1 Chapter 2 Research in Abnormal Psychology Slides & Handouts by Karen Clay Rhines, Ph.D. Seton Hall University

2. 2Comer, Abnormal Psychology, 6e – Chapter 2 Research in Abnormal Psychology Research is the key to accuracy in all fields Research is the key to accuracy in all fields Particularly important (and challenging) in the field of abnormal psychology 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 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 Only after rigorous testing can a theory or technique be considered valid or effective

3. 3Comer, Abnormal Psychology, 6e – Chapter 2 Research in Abnormal Psychology Clinical researchers face certain challenges that make their investigations particularly difficult: Clinical researchers face certain challenges that make their investigations particularly difficult: Measuring unconscious motives Measuring unconscious motives Assessing private thoughts Assessing private thoughts Monitoring mood changes Monitoring mood changes Clinical researchers must consider the cultural backgrounds, races, and genders of those they study 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 Clinical researchers must follow the code of ethics to ensure that their subjects are not harmed

4. 4Comer, Abnormal Psychology, 6e – Chapter 2 What Do Clinical Researchers Do? Clinical researchers try to discover laws and principles of abnormal psychological functioning: Clinical researchers try to discover laws and principles of abnormal psychological functioning: Search for nomothetic understanding Search for nomothetic understanding General or universal laws General or universal laws Generally do not assess, diagnose, or treat individual clients Generally do not assess, diagnose, or treat individual clients Use the scientific method to pinpoint relationships among variables Use the scientific method to pinpoint relationships among variables They systematically collect and evaluate information through careful observation They systematically collect and evaluate information through careful observation Use three methods of investigation to form and test hypotheses… Use three methods of investigation to form and test hypotheses…

5. 5Comer, Abnormal Psychology, 6e – Chapter 2 The Case Study Provides a detailed, interpretative description of a person’s life & psychological problems Provides a detailed, interpretative description of a person’s life & psychological problems Can serve as a source of new ideas about behavior Can serve as a source of new ideas about behavior Freud’s theories based entirely on case studies Freud’s theories based entirely on case studies May offer tentative support for a theory May offer tentative support for a theory May challenge a theory’s assumptions May challenge a theory’s assumptions May inspire new therapeutic techniques May inspire new therapeutic techniques May offer opportunities to study unusual problems May offer opportunities to study unusual problems

6. 6Comer, Abnormal Psychology, 6e – Chapter 2 The Case Study Has limitations: Has limitations: Observers are biased Observers are biased Relies on subjective evidence Relies on subjective evidence Has low internal validity Has low internal validity Provides little basis for generalization Provides little basis for generalization Has low external validity Has low external validity These limitations are addressed by the two other methods of investigation… These limitations are addressed by the two other methods of investigation…

7. 7Comer, Abnormal Psychology, 6e – Chapter 2 The Correlational Method & The Experimental Method Do not offer richness of detail Do not offer richness of detail Do allow researchers to draw broad conclusions Do allow researchers to draw broad conclusions Typically involve observing many individuals Typically involve observing many individuals Researchers apply procedures uniformly Researchers apply procedures uniformly Studies can be replicated Studies can be replicated Researchers use statistical tests to analyze results Researchers use statistical tests to analyze results

8. 8Comer, Abnormal Psychology, 6e – Chapter 2 The Correlational Method Correlation is the degree to which events or characteristics vary with each other Correlation is the degree to which events or characteristics vary with each other Measures the strength of a relationship Measures the strength of a relationship Does not imply cause and effect Does not imply cause and effect The people chosen for a study are its subjects or participants, collectively called a sample The people chosen for a study are its subjects or participants, collectively called a sample The sample must be representative The sample must be representative

9. 9Comer, Abnormal Psychology, 6e – Chapter 2 The Correlational Method Correlational data can be graphed and a “line of best fit” can be drawn Correlational data can be graphed and a “line of best fit” can be drawn Positive correlation = variables change in the same direction Positive correlation = variables change in the same direction Negative correlation = variables change in the opposite direction Negative correlation = variables change in the opposite direction Unrelated = no consistent relationship Unrelated = no consistent relationship

10. 10Comer, Abnormal Psychology, 6e – Chapter 2 Positive Correlation

11. 11Comer, Abnormal Psychology, 6e – Chapter 2 Negative Correlation

12. 12Comer, Abnormal Psychology, 6e – Chapter 2 No Correlation

13. 13Comer, Abnormal Psychology, 6e – Chapter 2 The Correlational Method The magnitude (strength) of a correlation is also important The magnitude (strength) of a correlation is also important High magnitude = variables which vary closely together; fall close to the line of best fit 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 Low magnitude = variables which do not vary as closely together; loosely scattered around the line of best fit

14. 14Comer, Abnormal Psychology, 6e – Chapter 2 Magnitude of Correlation

15. 15Comer, Abnormal Psychology, 6e – Chapter 2 The Correlational Method Direction and magnitude of a correlation are often calculated statistically Direction and magnitude of a correlation are often calculated statistically Called the “correlation coefficient,” symbolized by the letter “r” Called the “correlation coefficient,” symbolized by the letter “r” Sign (+ or -) indicates direction Sign (+ or -) indicates direction Number (from 0.00 to 1.00) indicates magnitude Number (from 0.00 to 1.00) indicates magnitude 0.00 = no consistent relationship 0.00 = no consistent relationship +1.00 = perfect positive correlation +1.00 = perfect positive correlation -1.00 = perfect negative correlation -1.00 = perfect negative correlation Most correlations found in psychological research fall far short of “perfect” Most correlations found in psychological research fall far short of “perfect”

16. 16Comer, Abnormal Psychology, 6e – Chapter 2 The Correlational Method Correlations can be trusted based on statistical probability Correlations can be trusted based on statistical probability “Statistical significance” means that the finding is unlikely to have occurred by chance “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 <.05), results are considered “significant” and thought to reflect the larger population By convention, if there is less than a 5% probability that findings are due to chance (p <.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 Generally, confidence increases with the size of the sample and the magnitude of the correlation

17. 17Comer, Abnormal Psychology, 6e – Chapter 2 The Correlational Method Advantages of correlational studies: Advantages of correlational studies: Have high external validity Have high external validity Can generalize findings Can generalize findings Can repeat (replicate) studies on other samples Can repeat (replicate) studies on other samples Difficulties with correlational studies: Difficulties with correlational studies: Lack internal validity Lack internal validity Results describe but do not explain a relationship Results describe but do not explain a relationship

18. 18Comer, Abnormal Psychology, 6e – Chapter 2

19. 19Comer, Abnormal Psychology, 6e – Chapter 2 The Correlational Method Two special forms of correlational study: Two special forms of correlational study: Epidemiological studies Epidemiological studies Reveal the incidence and prevalence of a disorder in a particular population Reveal the incidence and prevalence of a disorder in a particular population Incidence = number of new cases in a given period Incidence = number of new cases in a given period Prevalence = total number of cases in a given period Prevalence = total number of cases in a given period Longitudinal studies Longitudinal studies Observe one sample of participants on many occasions over a long period Observe one sample of participants on many occasions over a long period

20. 20Comer, Abnormal Psychology, 6e – Chapter 2 The Experimental Method An experiment is a research procedure in which a variable is manipulated, and the manipulation’s effect on another variable is observed An experiment is a research procedure in which a variable is manipulated, and the manipulation’s effect on another variable is observed Manipulated variable = independent variable Manipulated variable = independent variable Variable being observed = dependent variable Variable being observed = dependent variable Allows researchers to ask questions such as: Does therapy X reduce symptoms of disorder Y? Allows researchers to ask questions such as: Does therapy X reduce symptoms of disorder Y? Causal relationships can only be determined through experiments Causal relationships can only be determined through experiments

21. 21Comer, Abnormal Psychology, 6e – Chapter 2 Most Investigated Causal Questions in Clinical Research Does factor X cause a disorder? Does factor X cause a disorder? Is cause A more influential than cause B? Is cause A more influential than cause B? How does family communication and structure affect family members? How does family communication and structure affect family members? How does a disorder affect the quality of a person’s life? How does a disorder affect the quality of a person’s life? How does a person’s disorder affect family members? How does a person’s disorder affect family members? Does treatment X alleviate a disorder? Does treatment X alleviate a disorder? Is treatment A more helpful than treatment B? Is treatment A more helpful than treatment B? Why does treatment X work? Why does treatment X work? Does greater therapist expertise lead to greater progress in treatment? Does greater therapist expertise lead to greater progress in treatment? Can an intervention prevent abnormal functioning? Can an intervention prevent abnormal functioning?

22. 22Comer, Abnormal Psychology, 6e – Chapter 2 The Experimental Method Statistics and research design are very important 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 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: Three features are included in experiments to guard against confounds: The control group The control group Random assignment Random assignment Blind design Blind design

23. 23Comer, Abnormal Psychology, 6e – Chapter 2 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 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 By comparing the groups, researchers can better determine the effect of the independent variable Rules of statistical significance are applied Rules of statistical significance are applied

24. 24Comer, Abnormal Psychology, 6e – Chapter 2 The Experimental Method Researchers must also watch out for differences in the makeup of the experimental and control groups Researchers must also watch out for differences in the makeup of 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 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 Examples: coin flip; drawing names from a hat

25. 25Comer, Abnormal Psychology, 6e – Chapter 2 The Experimental Method A final confound problem is bias A final confound problem is bias To avoid bias by the participant, experimenters employ a “blind design,” in which participants are kept from knowing which condition of the study (experimental or control) they are in To avoid bias by the participant, experimenters employ a “blind design,” in which participants are kept from knowing which condition of the study (experimental or control) they are in One strategy for this is providing a placebo – something that simulates real therapy but has no key ingredient One strategy for this is providing a placebo – something that simulates 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 which condition of the study participants are in To avoid bias by the experimenter, experimenters employ a “double-blind design,” in which both experimenters and participants are kept from knowing which condition of the study participants are in Often used in medication trials Often used in medication trials

26. 26Comer, Abnormal Psychology, 6e – Chapter 2 Alternative Experimental Designs It is difficult to devise an experiment that is both well controlled and enlightening 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: Clinical researchers often must settle for designs that are less than ideal and include: Quasi-experimental designs Quasi-experimental designs Natural experiments Natural experiments Analogue experiments Analogue experiments Single-subject experiments Single-subject experiments

27. 27Comer, Abnormal Psychology, 6e – Chapter 2 Alternative Experimental Designs In quasi-experimental designs, investigators do not randomly assign subjects to groups, but make use of group that already exist 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 Example: children with a history of child abuse To address the problem of confounds, researchers use matched control groups 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 These groups are “matched” to the experimental group based on demographic and other variables

28. 28Comer, Abnormal Psychology, 6e – Chapter 2 Alternative Experimental Designs In natural experiments, nature manipulates the independent variable and the experimenter observes the effects In natural experiments, nature manipulates the independent variable and the experimenter observes the effects Example: psychological impact of flooding Example: psychological impact of flooding Cannot be replicated at will Cannot be replicated at will Broad generalizations cannot be made Broad generalizations cannot be made

29. 29Comer, Abnormal Psychology, 6e – Chapter 2 Alternative Experimental Designs Analogue experiments allow investigators to freely manipulate independent variables while avoiding ethical and practical limitations 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 They induce laboratory subjects to behave in ways that seem to resemble real life Example: animal subjects 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 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

30. 30Comer, Abnormal Psychology, 6e – Chapter 2 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 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 Experiments rely on baseline data to set a standard for comparison Common experimental designs are ABAB and multiple-baseline designs Common experimental designs are ABAB and multiple-baseline designs

31. 31Comer, Abnormal Psychology, 6e – Chapter 2 Alternative Experimental Designs In ABAB (reversal) designs, a participant’s 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) In ABAB (reversal) designs, a participant’s 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 himself or herself rather than against control subjects The subject is, essentially, compared against himself or herself rather than against control subjects

32. 32Comer, Abnormal Psychology, 6e – Chapter 2 Alternative Experimental Designs Multiple-baseline designs examine two or more dependent variables for change when an independent variable is introduced Multiple-baseline designs examine two or more dependent variables for change when an independent variable is introduced

33. 33Comer, Abnormal Psychology, 6e – Chapter 2 Alternative Experimental Designs Both types of single-subject experiments are similar to individual case studies Both types of single-subject experiments are similar to individual case studies Both focus on one subject only Both focus on one subject only Both have low external validity 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 However, both types of single-subject experiments have higher internal validity than the case study, given the manipulation of an independent variable