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Underreporting of psychopathology on the MMPI-2: a meta-analytic review
1Department of Psychology, 115 Kastle Hall, University of Kentucky, Lexington, Kentucky 40506-0044, USA. rbaer@uky.edu
Abstract:
Meta-analytic techniques were applied to studies of the MMPI-2 in which participants given standard instructions were compared with participants instructed or believed to have been underreporting. Traditional and supplementary indices of underreporting yielded a mean effect size of 1.25, suggesting that underreporting respondents differ from those responding honestly by a little more than 1 standard deviation, on the average, on these scales. Analyses of classification accuracy suggested that several scales are moderately effective in detecting underreporting, although accuracy decreases if participants have been coached about validity scales. Base rates of defensive responding in relevant populations are reviewed, and methodological issues, including research designs, coaching, and incremental validity of supplementary underreporting scales, are discussed.
Insights
Underreporting respondents on the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) differ significantly from honest responders, with validity scales showing moderate accuracy in detection. Coaching reduces detection effectiveness.
Area of Science:
- Psychological assessment
- Clinical psychology
- Forensic psychology
Background:
- The Minnesota Multiphasic Personality Inventory-2 (MMPI-2) is a widely used psychological test.
- Assessing response validity is crucial for accurate interpretation of MMPI-2 results.
- Underreporting or "faking bad" can distort assessment outcomes.
Purpose of the Study:
- To quantitatively synthesize research on the MMPI-2's ability to detect underreporting.
- To evaluate the effectiveness of traditional and supplementary underreporting validity scales.
- To examine factors influencing the accuracy of underreporting detection.
Main Methods:
- Meta-analysis of studies comparing standard vs. underreporting instructions on the MMPI-2.
- Calculation of mean effect sizes for underreporting scales.
- Analysis of classification accuracy and factors affecting it.
Main Results:
- A substantial mean effect size (1.25) indicates significant differences between underreporting and honest respondents.
- Several MMPI-2 scales demonstrate moderate accuracy in detecting underreporting.
- Detection accuracy is diminished when participants are coached on validity scales.
Conclusions:
- MMPI-2 validity scales are generally effective in identifying underreporting.
- Awareness of validity scales (coaching) compromises their detection utility.
- Further research is needed on base rates and methodological considerations.