Signal value and preliminary processes in OR elicitation.

The evoked cardiac response (ECR) of heart rate deceleration, respiratory pause, the peripheral pulse amplitude response (PPAR) of vascular constriction, and the galvanic skin response (GSR) were recorded from 20 subjects presented with a series of brief target and nontarget stimuli in a random order. Prestimulus vigilance was equivalent for the two types of stimuli since each had to be identified as target or nontarget before being processed, or ignored, respectively. This difference in signal value following identification affected only by the GSR, supporting a conceptualization of preliminary processes in orienting response (OR) elicitation rather than Sokolov's unitary OR concept.