پتانسیل های مرتبط با رویداد تفاوت پردازش عملکرد حافظه صادقانه در مقابل حافظه تمارض را نشان می دهد

Twenty-two undergraduate students completed a recognition memory test while event-related potentials (ERPs) were recorded. During the testing phase, subjects distinguished old from new words in a forced-choice format. There were two counterbalanced within-subject conditions, one in which subjects performed to the best of their abilities, and another with instructions to feign memory impairment. Test scores and response latencies differed significantly between the two conditions. Analysis of PCA-defined epochs revealed that old words were more positive than new in the control condition, with this difference confined to frontal regions and interpreted as reflecting familiarity-based recognition judgements. In the malingering task, this old/new word difference emerged earlier and was broadly distributed across the scalp. A discriminant function analysis using reaction time and ERP measures resulted in 82% correct classification of honest and simulated performance, with 79% correct on cross-validation.

An increasing range of methods to detect feigned memory impairment has been investigated recently. The majority of these use scores on existing neuropsychological and specifically designed tests to screen for non-optimal performance. However, test scores have been shown to be highly sensitive to coaching strategies which provide participants with information on how to present a believable deficit and thus avoid detection (Gunstad and Suhr, 2001, Lamb et al., 1994, Orr and Pitman, 1993, Rose et al., 1998, Suhr and Gunstad, 2000 and Youngjohn et al., 1999). As a result, an increasing number of researchers are now investigating other, more covert, measures to distinguish honest from feigned performance. For example, Rose et al. (1998) found significant differences in overall response latency between malingering, control and head-injured groups, but not between coached and uncoached malingerers. Other studies have suggested the value of event-related potentials (ERPs) as a means of detecting feigned deficits. These studies have predominantly focused on the P3 component of the ERP, and have demonstrated equivalent recognition of target stimuli in control and malingering subjects, despite reduced test performance in the malingerers suggestive of memory loss (Ellwanger et al., 1999, Rosenfeld et al., 1995 and Rosenfeld et al., 1998).