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Psychopaths show deviant responses to aversive stimuli.

SANTA FE, N.M. -- Psychopaths show decreased startle responses compared with nonpsychopaths when viewing aversive photographs, Edward M. Bernat, Ph.D., reported in a poster presentation at the annual meeting of the Society for Psychophysiological Research.

The results support the notion that psychopaths are less physiologically reactive to aversive stimuli and lack empathy, concluded Dr. Bernat of the University of Minnesota, Minneapolis.

The study compared 28 male psychopaths incarcerated at a medium-security prison with 23 nonpsychopathic inmates. Investigators showed each inmate 66 photographs taken from the International Affective Picture System (IAPS), a set of normative emotional stimuli for experimental investigations of emotion and attention.

Pleasant stimuli included erotic and action images such as nudes, surfing, or racing. Unpleasant stimuli included threat and victim images, such as aimed weapons, attack, and injury. Neutral stimuli included household objects and expressionless faces.

Each photo was displayed for 6 seconds, and during the display participants were startled by a loud sound--a 50-millisecond, 105-dB white noise probe--3-5 seconds after the beginning of the display. The magnitude of the participant's blink reflex served as the measure of his startle response.

Nonpsychopaths--those scoring 20 or below on the Psychopathy Checklist-Revised (PCL-R)--showed increased startle responses to aversive stimuli and decreased startle responses to pleasant stimuli compared with neutral stimuli. Psychopaths--those scoring above 30 on the PCL-R--showed the normal decrease in startle responses to pleasant stimuli, but showed significantly less increase in startle to aversive stimuli.

When the aversive stimuli were ranked by intensity, nonpsychopaths showed increasing startle as they moved from low-intensity to moderate-intensity to high-intensity images. Psychopaths, on the other hand, showed no increase in startle to the most intense images.

Nonpsychopaths showed increasing startle with increasing intensity for both threat and victim stimuli. Psychopaths showed a lack of startle potentiation for victim stimuli and reduced potentiation for moderate-intensity and high-intensity threat stimuli.
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Title Annotation:Forensic Psychiatry
Author:Finn, Robert
Publication:Clinical Psychiatry News
Geographic Code:1USA
Date:Dec 1, 2004
Previous Article:Psychopaths appear less attuned to facial emotions.
Next Article:Incarcerated women experience mental decline.

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