Some commentators have suggested that more sensitive assessment of psychological injury, including PTSD, can be achieved with psychophysiological measurement (Friedman, 1991; Pitman and Orr, 1993). This notion is based on the premise that malingerers may be less able to mimic biological markers of PTSD than self-reported symptoms. The basis for this perspective is the considerable evidence that people with PTSD can be distinguished from those without PTSD on a range of autonomic responses to cues that are specific to their trauma (for a review, see Orr and Kaloupek, 1997). For example, heart rate, skin conductance response, and eyeblink startle have been repeatedly found to be elevated in PTSD individuals when presented with trauma reminders. Further, there is recent evidence that functional magnetic resonance imaging (fMRI) can effectively distinguish the neural networks activated in PTSD and control participants when subliminally presented with threatening stimuli (Rauch et al., 2000). The extent to which these biological indicators can effectively discriminate between people with PTSD and those intentionally feigning PTSD has been rarely studied. Most reports that attempt to justify the use of psychophysiological assessment in psychological assessments tend to rely on a substantive literature that distinguishes the psychophysiological responses of people with and without a psychological injury (e.g. Neal et al., 1999). The utility of these measures in compensation matters relies, however, on their ability to differentiate between genuine claimants and those who are malingering. In one study, veterans without PTSD were able to increase their reactivity to a level that was comparable to veterans with PTSD (Gerardi et al., 1989). Orr and Pitman (1993) found that whereas veterans instructed to respond as if they had PTSD were able to mimic heart rate responses of veterans with PTSD, they could not mimic skin conductance and electromyogram patterns. Overall, psychophysiological measures cannot be regarded as reliable indicators of genuine or malingered PTSD. Although psychohysiological data can be used to present the claimant's physiological responses in the context of current knowledge about the psychophysiology of the disorder, reliance on current scientific knowledge precludes definitive comments being made about malingering on the basis of this type of evidence.
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