affective imagery: Sex differences. Psychophysiology, 17, 75-82. imagery in depressed and nondepressed subjects. Science, New York, 192, 489-491. changes. Biological Psychology. and tonic autonomic changes. Psychophysiology, 18, 403-409.

Two experiments tested the view that task‐induced autonomic‐somatic gradient parallelism does exist and that the steeper the physiological gradients, over the course of a task, the more involved the subject and the greater the effort. Thirty‐three male subjects performed easy and difficult versions of a continuous reaction time task. In both experiments the difficult task prompted steeper electromyographic (EMG) activity gradients than did the easy version. Scores on heart rate (HR) and skin conductance did not show clear gradients. However, task‐dependent effort was positively related to the magnitude of the initial HR acceleration and to the steepness of the EMG gradient. The autonomic‐somatic coupling hypothesis of Obrist did not explain the results. Instead, evidence for ventilatory‐somatic parallelism was found.