Psychopathy and physiological responses to adrenalin.

Physiological recordings were taken while 16 psychopaths (P), 16 nonpsychopaths (NP), and 16 "mixed" (M) 5s received an injection of saline, followed 15 min. later by an injection of adrenalin. Tonic skin conductance of Group NP was generally greater than that of Groups M and P, a difference that increased throughout the course of the experiment. There were no significant group differences in tonic heart rate, respiration rate, blink rate, or electromyogram (EMG) activity. Both saline and adrenalin injections produced sharp increases in skin conductance, blink rate, digital vasoconstriction, and EMG activity, but these changes were more persistent with adrenalin. Adrenalin also produced large and prolonged increases hi heart rate, while saline had virtually no effect on heart rate. With one exception, there were no significant differences between groups in responsivity. The exception involved electrodermal activity—the increases in skin conductance following saline and adrenalin were smaller in Group P than they were in Group NP. Physiological responses given by each group were unrelated to scores on the Activity Preference Questionnaire. The results therefore do not support earlier claims that psychopaths show extreme cardiac lability in response to adrenalin. On the other hand, they are consistent with the view that psychopaths are electrodermally hypoactive.