Use of the Stroop phenomenon as a diagnostic tool for malingering

To assess a computerised version of the Stroop test for detection of malingering of cognitive deficit.

Sixty subjects were assessed using this test. Twenty had cognitive deficits due to brain damage of miscellaneous aetiologies. Ten were healthy, not acquainted with the test, and were asked to simulate cognitive impairment. Another 10 simulators were psychology students trained in the use of the test. Twenty healthy subjects served as controls. Results were analysed for reaction time, error percentage, and the Stroop effect.

There was a significant difference in reaction time among groups, showing a direct relation of age among control subjects, and also longer reaction time in patients with brain damage than in controls. Controls and patients with brain damage showed a clear Stroop effect. Simulators had a significantly prolonged reaction time, increased error percentage, and inverted or absent Stroop effect. This alteration of the Stroop effect is never present in organic cognitive deficits and seems to be a characteristic pattern of feigning, independently of knowledge of the test.

This technique is recommended as a valuable tool to detect feigned cognitive impairment.