Anticipation Of Electric Shock Research Articles

Induced fear reduces the effectiveness of a placebo intervention on pain

Fear was induced by the anticipation of electric shock in order to investigate whether fear reduced the effectiveness of a placebo intervention on reported pain and the acoustic startle reflex. Thirty-three subjects participated in a 3 Condition (Natural History [NH], Placebo [P], Placebo+Fear [PF])×3 Test (Pretest, Posttest 1, Posttest 2) within-subject design, tested on 3 separate days. Measures of fear were fear of pain (FOP), measured by the Fear of Pain Questionnaire (FPQ-III); fear-potentiated startle; and a self-report measure that assessed the effectiveness of the fear induction procedure. In the pain intensity data, there was a trend towards a placebo effect. This trend was abolished by induced fear, and was most pronounced in subjects who were highest in measures of fear. The placebo manipulation also caused a reduction in startle reflex amplitude. This effect was abolished by induced fear, and was strongest amongst high FOP subjects. In conclusion, induced fear abolished placebo analgesia, and this effect was strongest in subjects who had high scores on measures of fear.

Fear-potentiated startle in posttraumatic stress disorder

Exaggerated startle is reputed to be one of the cardinal symptoms of posttraumatic stress disorder (PTSD); however, objective studies have given conflicting results as to whether or not startle is increased in PTSD. The present study investigated startle in PTSD during the threat of shock (fear-potentiated startle). The eyeblink component of the startle reflex was measured at various times preceding and following the anticipation of unpleasant electric shocks in 9 PTSD subjects and 10 age-matched, healthy controls. Startle amplitude was significantly greater during baseline and during shock anticipation in the PTSD subjects, compared to the controls. Habituation of the startle reflex was normal. Because other studies in the literature, as well as in our own laboratory, have failed to find exaggerated startle at baseline (i.e., absence of stress) in PTSD patients, it is unlikely that the present results reflect a chronic elevation of startle in this group. Instead, the higher levels of startle in the PTSD group probably resulted from a greater conditioned emotional response in this group, triggered by anticipation of electric shocks that generalized to the unfamiliar experimental context in which testing occurred. Hence, emotionally charged test procedures may be especially informative in distinguishing PTSD patients from other psychiatric diagnostic groups.

Measuring the time course of anticipatory anxiety using the fear-potentiated startle reflex.

The time course of the facilitation of the acoustic startle reflex induced by anticipation of electric shocks was measured in 20 normal volunteers. Shocks could be administered during the last 10 s of 45-s threat conditions but not during 50-s no-threat conditions, each condition being signaled by a different light. Consistent with previous data, overall eyeblink startle levels were higher during the threat than during the no-threat conditions. However, the magnitude of this fear-potentiated startle effect became progressively larger in the threat condition the longer the light was on and then abruptly decreased with the onset of the light signaling the no-threat condition. These effects of the threat of shock on startle were interpreted in terms of anticipatory anxiety. Other interpretations, such as changes in selective or generalized attention, were also discussed. This paradigm provides a method to assess the time course of anticipatory anxiety in humans.

The effect of chlordiazepoxide on the anticipation of electric shocks

The action of 20 mg chlordiazepoxide upon two different anxiety-evoking conditions in comparison with a control condition was investigated in a double-blind, placebo controlled study with 90 healthy male students. The Ss were told to expect an electric shock two times as strong under one condition and five times as strong under the other one in relation to a shock they had previously found unpleasant. During the anticipation interval of 20 min duration HR, GSR, respiration rate, and a rating of subjective emotional arousal were continuously recorded. The greatest effects of stress could be observed within the last 2 min of the anticipation interval, while interactions between drug- and stress-conditions occurred only at the beginning of the 20-min interval. Under the strong stress condition chlordiazepoxide showed an anxiety-reducing effect, under the control condition, however, paradoxical effects.

Aversive situational effects on alpha feedback training.

Anticipation of electric shock did not depress alpha activity in a feedback situation though it was associated with reported anxiety and heightened arousal indexed by greatly increased heart rate and number of spontaneous skin conductance responses. Contrary to previous reports, a reduction in alpha activity is not a necessary consequence of apprehension or heightened arousal.

Vigilant and nonvigilant coping strategies and pscyhophysiological stress reactions during the anticipation of electric shock.

Vigilant and nonvigilant coping strategies and pscyhophysiological stress reactions during the anticipation of electric shock.

Anticipation of electric shock: A psychophysical study

Successive measures of emotional intensity were obtained by a two-step scaling procedure from 23 subjects anticipating an electric shock to be given at the end of a 45-min period. Half of S s had a clock available, while the other half had to estimate apparent time. The emotional reaction was shown to increase exponentially as time before shock decreased. Heart rate also increased as time for shock was approaching, but the trend was not regular.