Personality characteristics of patients showing suboptimal cognitive effort.

This study examined the relationship between performance on the Portland Digit Recognition Test (PDRT) and the MMPI-2 in a group of veterans who were suspected of having motivation to exaggerate cognitive and/or psychiatric symptoms. Number correct on "easy" trials on the PDRT correlated inversely with MMPI-2 measures of psychopathology, whereas number correct on "hard" trials positively correlated with the same scales. Some individuals performed poorly across both types of PDRT trials and had significant MMPI-2 elevations, whereas others performed poorly only on "hard" PDRT trials and had less extreme MMPI-2 elevations. This study reinforces the need to assess the validity of both cognitive and psychiatric symptom complaints.