The Effects of Expectancy Upon Electrodermal Responses to Signaled Stimuli

The research evaluates the role of expectancy in determining magnitude of electrodermal response to a moderately loud noise. Main emphasis was upon comparisons of response magnitudes when the intensity received confirmed that which was expected and when the intensity received was different from that expected. Based on preliminary observations which suggested that response magnitudes shifted in a direction corresponding to stimulus intensity expected, the experiment varied direction of change and evaluated subjective intensity of stimuli received, as well as magnitude of electrodermal responding. Perceived intensities of the noise stimuli were influenced by the direction of shift in the same fashion as electrodermal response magnitudes. Examination of factors determining electrodermal responses to the noises showed several contributing variables: the direction of shift from expectation, the subjective intensity of stimuli, and the amount of anticipatory electrodermal activity just prior to noise onset.