The effect of a threatening context upon motivation and task-induced physiological changes.

The effect of a threatening context upon tonic task-induced physiological changes was tested in an experiment where 14 male subjects performed a continuous perceptual motor task for 150 seconds, once with and once without threat of aversive electric shock (counterbalanced order). Results indicated that task-irrelevant muscular tension increased and skin temperature decreased over the course of a task, and these gradients were steeper with threat than for the no-threat treatment. Initial heart-rate increase was marked for the threat condition. For respiration, a trend parallel to muscular gradients emerged with no-threat as contrasted with a parallel respiratory-cardiac activation with threat. Subjects' ratings on items reflecting self-perception responded to the threat manipulation, but ratings on items reflecting task perception remained unaffected.