A Laboratory Word Memory Test Analogue Differentiates Intentional Feigning from True Responding Using the P300 Event-Related Potential

Symptom exaggeration and feigned cognitive impairment occur commonly in forensic and medicolegal evaluations. As a result, methods to detect feigned cognitive impairment are an indispensable component of neuropsychological assessments. This study reports the results of two neurophysiological experiments using a forced-choice recognition task built from the stimuli of the Word Memory Test and Medical Symptom Validity Test as well as a new linguistically informed stimulus set. Participant volunteers were instructed either to do their best or to feign cognitive impairment consistent with a mild traumatic brain injury while their brain activity was monitored using event-related potentials (ERP). Experiment 1 varied instructions across individuals, whereas Experiment 2 varied instructions within individuals. The target brain component was a positive deflection indicating stimulus recognition that occurs approximately 300 ms after exposure to a stimulus (i.e., the P300). Multimodal comparison (P300 amplitude to behavioral accuracy) allowed the detection of feigned cognitive impairment. Results indicate that, for correct responses, P300s were equivalent for the simulated malingering and good effort conditions. However, for incorrect responses, feigned impairment produced reliable but significantly reduced P300 amplitudes. Although the P300 is an automatic index of recognitioneven when knowledge is hiddenits amplitude appears capable of modulation by feigning strategies. Implications of this finding are discussed for research and clinical applications.