Variation in physiological and behavioral activity as reflected in changes in arousal level

The purpose of the present study was to investigate heart rate, skin conductance, and reaction time as reflected in changes in arousal level in an effort to resolve some of the conflict between the various interpretations of the activation process. Three interpretations have been stressed in this paper: (a) general arousal theory, (b) stimulus specific theory, and (c) the Webb and Obrist Model. The last theory is considered to be part of a more general behavioral response which might have a common origin and be mediated by central processes. The subjects were four graduate psychology students, two male and two female, aged 21 to 43 years. The independent variables were threat of shock, schedule of stimulus presentation, and presence of relevant and irrelevant stimuli. The dependent variables included reaction time, heart rate, and skin conductance. Arousal level was manipulated by the use of shock and fixed and variable interval schedules. The idea that arousal or activation varies along a single continuum in accordance with the energy requirements of the situation and the direction of behavior was supported by the present study. Changes in both heart rate and skin conductance transient from one stimulus to the next reflected similar variations. Also, there appeared to be an increase in physiological activity across all subjects concomitant with increased arousal level despite individual idiosyncracies