Abstract
The current investigation was designed to examine the impact of underreporting response bias on the Multidimensional Personality Questionnaire (MPQ) and the utility of the Unlikely Virtues scale in detecting such responding. Study participants were randomly assigned to either the underreporting (n = 100) or standard instruction (n = 224) conditions. All participants first completed a series of extratest measures under standard instruction prior to the MPQ administration. The results showed that individuals in the underreporting condition scored significantly higher on MPQ scales that reflect positive emotionality and self-control and lower on scales that indicate negative emotionality compared to those in the standard instruction. Moreover, the psychometric validity of MPQ scale scores against extratest measures was substantially attenuated in the underreporting condition compared to the standard instruction condition. The Unlikely Virtues scale differentiated between the conditions at a large effect size magnitude (Hedges' g = 1.21) and showed promising classification accuracy though lower cut scores than those reported in the MPQ manual performed substantially better with respect to sensitivity. Future research needs to replicate these findings in more naturalistic settings with other research designs.
Significance: The present study evaluated the Multidimensional Personality Questionnaire in detecting individuals who engage in overly defensive responding. The results showed that a scale designed to assess positive impression management and overly virtuous responding was very promising in this regard. This finding will have important implications for the use of the test in personnel screening and selection.