Effects of stimulus omission and stimulus change on dishabituation of the skin conductance response

Three experiments examined the effects of stimulus omission and stimulus change on dishabituation of the skin conductance response. In all experiments, subjects received 17 tone-light or light-tone (S1-S2) pairings, and the primary manipulations were omission of and change in S2 on Trial 16. Responses to S1 and S2 on Trial 17 constituted the data of primary interest. Experiment 1 (N = 72) demonstrated that omission of an expected stimulus was more effective in producing dishabituation than was presentation of an unexpected but not experimentally novel stimulus. Experiment 2 (N = 60) indicated that both omission of an expected stimulus and presentation of an unexpected and experimentally novel stimulus produced dishabituation. Experiment 3 (N = 72) revealed that both the omission and the miscuing of 52 produced reliable dishabituation. The results are interpreted as indicating the importance of a comparison between current input and the stored representation of previous stimulation in the development of habituation.