This intervals between warning stimuli and imperative stimuli
This research study was done to determine contingent negative variation in psychopaths. It rectified diagnostic and methodological problems witnessed in previous studies in order to bring out the definite findings on contingent negative variation in psychopaths. It sampled 29 male prisoners who had volunteered for study.
They were grouped into two; psychopaths and nonpsychopaths based on psychopathy check list score. Psychopaths forewarned reaction time task guided by time duration was performed in relation to warning stimulus and imperative stimulus and recorded on psychopathy check list. These results were later analyzed to determine psychopath’s contingent negative variation (Adelle & Robert, 1989).
Past research studies indicated that; psychopath’s anticipatory autonomic responses are different, they showed a weak behavioral activation system, normal behavioral activation system and are more responsive to rewarding than in punishment.
They also, indicated that a slow negative potential shift occurred in intervals between warning stimuli and imperative stimuli and it failed to show classic condition response by showing little or no contingent negative variation activity warning intervals. This scenario relates to Gray’s theory in that rewarding psychopaths prompted them to exhibit certain behavior, while punishment inhibited the same behavior (Adelle & Robert, 1989).
Raine and Venables criticized earlier research studies on psychopath’s contingent negative variation by concluding that there was no way of knowing whether or not any of the antisocial subjects would meet the criteria for psychopathy.
They added that previous studies were based on false premise concluding that psychopaths are generally poor at learning relation between events. They also highlighted that although autonomic data indicated that psychopaths are not fearful in anticipation of aversive stimulation there was no reason to assume that they were unaware of contingencies involved (Adelle & Robert, 1989).
Forth and Hare predicted that psychopaths were incapable of having cognitive or motivational process thought to underlie the contingent negative variation and they had the ability to focus on attention on events that interest them.
They also predicted that, psychopath’s contingent negative variation in tasks that are sufficiently interesting and motivating was larger than those of normal individuals. The difference between the early contingent negative variation and late contingent negative variation is that, early contingent negative variation reaches its maximum within the first few seconds after the warning stimulus.
It is largest over frontal regions and reflects task demands as well as the physical properties, significance, processing and warning stimulus. Late contingent negative variation peaks just before the imperative stimulus. It is largest over precentral and central regions and it may reflect motor preparation and response demand (Adelle & Robert, 1989).
In reference to early contingent negative variation and late contingent negative variation for psychopaths, this study had predicted that; psychopaths are interested in paying close attention to task relevant their demands, early contingent negative variation would be larger than those of nonpsychopaths, all subjects would be motivated to respond rapidly to imperative stimulus there by maximizing gains and minimizing loses, no group difference in the late contingent negative variation or in reaction time, and that psychopaths would show an enhanced early contingent negative variation and a normal late contingent negative variation (Adelle & Robert, 1989).
In this study, 29 white male inmates were voluntarily picked from provincial prison. Inclusion criteria included; age between 18 and 45 years, normal hearing and free from neurological impairment. To measure psychopathy; researcher used institutional files and conducted a semi structured interview to complete psychopathy checklist.
Participants completed the state trait anxiety inventory. Each participant was given 20 trials to push a button as quickly as possible in response to a 1300 Hz single tone. The reaction time of each participant was ordered from slow to fast and his criterion defined as the time falling at the 75th percentile of his distribution. The prediction of a difference for early contingent negative variation in psychopaths was lower than for non psychopaths. This difference was not statistically significant (Adelle & Robert, 1989).
There was no significant group or condition difference in the number of failures to respond faster than individually set reaction time threshold. Apparently, psychopaths could not be distinguished from non psychopaths on the basis of their performance. The difference for late contingent negative variation was not significant.
Interpretation of the early contingent negative variation difference was significantly larger in psychopaths than in nonpsychopaths. Psychopaths are proficient at allocating attention resources to events that interest them and are not deficient in psychological processes that underlie contingent negative variations (Adelle & Robert, 1989).
The weakness of this study was that the research design used lacked sufficient power to detect a reliable group difference. Research results did not confirm to predictions that psychopaths differ from the others in their ability to maintain attention during a long fore period and in the face of external distractions (Adelle & Robert, 1989).
This research study concludes by indicating that sufficiently motivated psychopaths show no evidence of electrocortical or behavioral impairment in contingent negative variation. It also indicates that, psychopaths are proficient in focusing attention on events of immediate interest to them (Adelle & Robert, 1989).
Adelle, E. F., & Robert, D. H. (1989). The contingent negative variation in psychopaths. The society for psychophysiological research, 26(6), 676- 681.