Correlates of Differences in Time to Recover from Startle

The present study was designed to test the hypothesis that those who recover quickly from startle would reveal physiological differences from those who recover slowly. Forty-two male undergraduates served as subjects. The following variables were recorded: systolic and diastolic blood pressures; finger, face, and axillary temperatures; palmar and volar skin resistances; heart and respiration rates; stomach motility; finger pulse volume; and frontal, temporal, parietal, and occipital brain potentials. Indices computed were Wenger's estimate of autonomic balance (Ā), percent-time alpha, and time to reappearance of alpha. Subjects were instructed to depress a reaction time key as quickly as possible after hearing a pistol shot. Following preliminary measurements and 12 minutes of collecting resting data, a .22-caliber blank pistol was fired, after which recording continued for another 4 minutes. Of the 42 subjects, the 10 with the fastest reaction times were compared to the 10 with the slowest reaction times. The groups differed significantly only in diastolic blood pressure in their prestimulus resting levels, the fast reactors having the higher pressure. Following stimulation, the slow reactors showed greater increases in systolic blood pressure, pulse pressure, palmar skin conductance, heart rate, and decrease in finger pulse volume. It was concluded that greater autonomic responsiveness is associated with slower recovery from startle.