Effects of psychological defense on processing of neutral stimuli indicated by event-related potentials (ERPs)

The Defense Mechanism Test (DMT) is claimed to identify personnel with a high risk for accidents. A new explanation for why the DMT seems to predict performance when survival depends on split second decisions is proposed. Sixteen right-handed, adult male students were tested with the DMT and with an ERP paradigm (two sine wave tones, presented binaurally). Each subject was tested with a one-stimulus paradigm, and a passive and an active oddball paradigm. Under the passive oddball condition, High defensive subjects differed from Low, having significantly smaller N2 amplitudes (low immediate perception), and significantly larger P3 amplitudes (rely on later associative mechanisms). High defensive subjects seem to have less ability to perceive the environment correctly immediately. This slowness may be fatal when life depends on split second decisions. The fundamental neurophysiological difference may also be the basis for the very complex cognitive and perceptual mechanisms involved in psychological defense mechanisms.