Cardiac and Somatic Response Patterns During a Reaction Time Task in Children and Adults

Psychophysiological responses were studied in 25 fifth grade boys and 25 male college students during a choice reaction lime task. Attention to the task was manipulated through changes in two variables: uncertainly and motivation. Heart rate responses reflected changes in uncertainty for both groups. Heart rate, forearm EMG, eye blinks and movements, and general body movement differentiated between two levels of motivation. These results indicated that children and adults responded similarly, and that heart rate and forearm EMG were the most sensitive indices of changes in stimulus variables. Further examination of cardiac and somatic responses revealed an association between cardiac and task-relevant somatic activity. A study of response patterns over trials confirmed (his relationship, which was discussed in terms of a two-process model.