The validity of the M test in a residential forensic facility

The validity of the M Test as a screening measure for malingering was assessed in a residential forensic treatment center. Clinically, malingering was recognized by the treatment staff as a significant problem among incompetent to proceed (ITP) defendants in this setting. A total of 79 ITP defendants completed the M Test under standard instructions. To assess the predictive validity of the M Test, its sensitivity and specificity were determined using three separate measures of malingering status. Using the original scoring procedure, the results provided estimates of sensitivity of 11, 31, and 29 percent and estimates of specificity of 67, 70, and 69 percent, respectively, for the three malingering status measures. A revised scoring procedure improved the sensitivity estimates to the statistically significant level of 86 percent for the malingering status measure that was defined as feigned or grossly exaggerated psychotic symptoms. The pattern of correlations between the M Test scales and a variety of other clinical measures suggested that, in this forensic treatment setting, the subject's pattern of responses to the M Test was primarily determined by the severity of cognitive impairment of that subject.