Abnormal Psychology, Twelfth Edition by Ann M. Kring, Sheri L. Johnson, Gerald C. Davison, & John M. Neale & John M. Neale Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

 Chapter 4: Research Methods in the Study of Psychopathology Psychopathology I. Science and Scientific Methods II. Approaches to Research on Psychopathology III. Integrating the Findings of Multiple Studies © 2012 John Wiley & Sons, Inc. All rights reserved.

 Science = “to know” The systematic pursuit of knowledge through observation The systematic pursuit of knowledge through observation Scientists gather data to test theories Scientists gather data to test theories  Theory Set of propositions developed to explain what is observed Set of propositions developed to explain what is observed  A good theory is falsifiable  Allows for disconfirmation  Hypotheses Specific predictions about what will occur if a theory is correct Specific predictions about what will occur if a theory is correct © 2012 John Wiley & Sons, Inc. All rights reserved.

 Detailed biographical description of an individual Family history Family history Medical status Medical status Educational and work background Educational and work background Information about peer and romantic relationships Information about peer and romantic relationships Personality and adjustment issues Personality and adjustment issues Current difficulties and prior experiences in therapy Current difficulties and prior experiences in therapy  Usefulness Rich description, especially helpful for rare disorders Rich description, especially helpful for rare disorders Disprove hypothesis Disprove hypothesis Generate hypotheses Generate hypotheses  Limitations Paradigm may influence observations Paradigm may influence observations Cannot rule out alternative explanations Cannot rule out alternative explanations Cannot prove hypothesis Cannot prove hypothesis © 2012 John Wiley & Sons, Inc. All rights reserved.

 Do variable X and variable Y vary together? Are they related in a systematic way? Are they related in a systematic way?  Do people who experience more stress have more headaches?  Variables measured but not manipulated  Cannot determine cause or effect © 2012 John Wiley & Sons, Inc. All rights reserved.

 Correlation Coefficient (r.) Varies from -1.0 to +1.0 Varies from -1.0 to +1.0  e.g., -1.0, -0.65, -0.33, 0, +0.22, +0.70,  Strength The higher the absolute value, the stronger the relationship The higher the absolute value, the stronger the relationship  (-0.9 > +0.6; +0.9 > -.08)  Direction Positive Positive  Higher scores on Variable X associated with higher scores on Variable Y Negative Negative  Higher scores on Variable X associated with lower scores on Variable Y © 2012 John Wiley & Sons, Inc. All rights reserved.

 Statistical significance Probability ≤.05 Probability ≤.05 Can be influenced by number of participants Can be influenced by number of participants  Larger samples increase likelihood of significance  Clinical significance Is the association meaningful as well as statistically significant? Is the association meaningful as well as statistically significant? © 2012 John Wiley & Sons, Inc. All rights reserved.

 Correlation does not imply causality  Directionality problem Variable X may cause Variable Y Variable X may cause Variable Y Variable Y may cause Variable X Variable Y may cause Variable X  Third-variable problem Variable Z causes both Variable X and Variable Y Variable Z causes both Variable X and Variable Y © 2012 John Wiley & Sons, Inc. All rights reserved.

 Longitudinal Studies participants over time Studies participants over time Examines whether causes are present before disorder develops Examines whether causes are present before disorder develops High-Risk Method High-Risk Method  Include only those who are at greatest likelihood of developing a disorder  Reduces the cost of longitudinal research  Cross-sectional Causes and effects measured at the same time Causes and effects measured at the same time  Confounds Third variable may produce changes in two correlated variables Third variable may produce changes in two correlated variables © 2012 John Wiley & Sons, Inc. All rights reserved.

 Epidemiology Study of the distribution of disorders in a population and possible correlates Study of the distribution of disorders in a population and possible correlates  Three features of a disorder Prevalence Prevalence Incidence Incidence Risk Factors Risk Factors  The National Comorbidity Survey–Replication Large-scale national survey Large-scale national survey Used structured interviews to collect information on the prevalence of several diagnoses (Kessler et al., 2005). Used structured interviews to collect information on the prevalence of several diagnoses (Kessler et al., 2005). © 2012 John Wiley & Sons, Inc. All rights reserved.

 Methods to determine genetic predisposition (concordance) to psychopathology Family Method Family Method Twin Method Twin Method Adoptees Method Adoptees Method © 2012 John Wiley & Sons, Inc. All rights reserved.

 Family studies First-degree relatives (parents, children, siblings) First-degree relatives (parents, children, siblings)  50% shared genes Second-degree relatives (aunts, uncles, grandparents) Second-degree relatives (aunts, uncles, grandparents)  25% shared genes Index cases/Probands Index cases/Probands  Sample of individuals with psychopathology  Twin studies Monozygotic (MZ) or identical twins Monozygotic (MZ) or identical twins  100% shared genes Dizygotic (DZ) or fraternal twins Dizygotic (DZ) or fraternal twins  50% shared genes Concordance Concordance  Co-occurrence or similarity of diagnosis  Adoption studies Study of adoptees who have biological parents with psychopathology Study of adoptees who have biological parents with psychopathology  Cross-fostering Study of adoptees who have adoptive parents with psychopathology Study of adoptees who have adoptive parents with psychopathology © 2012 John Wiley & Sons, Inc. All rights reserved.

 Association studies Examine the relationship between a specific allele and a trait or behavior in the population Examine the relationship between a specific allele and a trait or behavior in the population  Genome-wide association studies (GWAS) Examines the entire genome of a large group of people to identify variations between people Examines the entire genome of a large group of people to identify variations between people © 2012 John Wiley & Sons, Inc. All rights reserved.

 Provides information about causal relationships  Involves: Random assignment Random assignment Independent variable (manipulated variable) Independent variable (manipulated variable) Dependent variable (measured variable) Dependent variable (measured variable)  Can evaluate treatment effectiveness  Experimental Effect Differences between groups Differences between groups © 2012 John Wiley & Sons, Inc. All rights reserved.

 The investigator manipulates an independent variable.  Participants are assigned to the conditions by random assignment.  Researcher measures a dependent variable that is expected to vary with conditions of the independent variable.  Experimental effect Differences between conditions on the dependent variable Differences between conditions on the dependent variable © 2012 John Wiley & Sons, Inc. All rights reserved.

 Internal validity Extent to which experimental effect is due to independent variable Extent to which experimental effect is due to independent variable  Control Group Participants who do not receive treatment Participants who do not receive treatment Standard against which treatment effectiveness is judged Standard against which treatment effectiveness is judged  External validity Extent to which results generalize beyond the study Extent to which results generalize beyond the study  Would results apply to others besides the study participants? © 2012 John Wiley & Sons, Inc. All rights reserved.

 Research designed to answer the question: “Does treatment work?”  Empirically supported treatments Treatment Manuals Treatment Manuals Control Groups Control Groups  Placebo  Double-blind procedure Sample Composition Sample Composition  Exclusion of diverse populations Efficacy and Effectiveness Efficacy and Effectiveness Need for dissemination Need for dissemination © 2012 John Wiley & Sons, Inc. All rights reserved.

 Experiments not always possible in psychopathology Ethical or practical constraints Ethical or practical constraints  Examine related or similar behavior in the lab Induce temporary symptoms Induce temporary symptoms Recruit participants with similarities to diagnosable disorders Recruit participants with similarities to diagnosable disorders  College students who tend to be anxious or depressed Animal research Animal research © 2012 John Wiley & Sons, Inc. All rights reserved.

 Examine how individual participants respond to changes in the independent variable.  Reversal (ABAB) Design The reversal technique not always possible The reversal technique not always possible  Initial state may not be recoverable © 2012 John Wiley & Sons, Inc. All rights reserved.

 Meta-analysis Identify relevant studies Identify relevant studies Compute effect size Compute effect size  Transforms results to a common scale  Smith et al. (1980) Meta-analyzed 475 outcome studies Meta-analyzed 475 outcome studies  Involved 25,000 subjects Results: Psychotherapy is effective Results: Psychotherapy is effective © 2012 John Wiley & Sons, Inc. All rights reserved.

Copyright 2012 by John Wiley & Sons, Inc. All rights reserved. No part of the material protected by this copyright may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission of the copyright owner. © 2012 John Wiley & Sons, Inc. All rights reserved.