Effect of the orienting response on sensory discriminability.

The effects of orienting responses to different types of stimuli on acquisition of information were studied. Subjects underwent a standard habituation series of 15 trials. On Trial 16, they received one of following three stimuli: (a) no-change stimulus--same stimulus as habituation stimulus, (b) innocuous-change stimulus, (c) significant-change stimulus--the subject's own name. These orienting stimuli were followed 500 msec. later by an imperative stimulus (100 msec.) which contained a number of Chinese characters. The subjects were then unexpectedly asked to recall and recognize these characters. Recall and recognition were consistently superior in conditions with significant and innocuous change relative to no change, which indicated that the orienting response to unexpected stimuli is related to a generalized perceptual enhancement. The data pose problems for the position that the orienting response reflects only the passive 'registration' of the eliciting stimulus information. While digital pulse-amplitude data showed no difference among the conditions for the change trial, these conditions were differentiated by electrodermal and cardiac changes.