Physiological and behavioral concomitants of mild stress: The effects of accuracy of temporal information

Sixty human subjects were exposed to a mild auditory stress after a fixed anticipatory period during which they performed a reaction time task. Suspense subjects were correctly informed of the time of onset of stress; Surprise subjects were told to expect the stress 10 min. later than it actually occurred. Subjects were provided with elapsed time information either automatically or on demand. Suspence subjects showed larger anticipatory electrodermal responses and smaller responses to stress than Surprise subjects but the two groups did not differ in their ratings of the unpleasantness of the stress. Female subjects showed greater anticipatory responses and consistently slower reaction times than males. The data are discussed in terms of explanations of the negative preception effect.