Dishabituation of the electrodermal orienting response following decay of sensitization.

This study tested one of the basic propositions of dual-process theory (Groves and Thompson, 1970) that 'dishabituation' results from an independent, superimposed process of excitation and not from disruption of the habituation process as proposed by Sokolov (1963). Skin conductance level (SCL) was employed as a measure of sensitization. On the basis of dual-process theory, it was hypothesized that if sensitization produced by the 'dishabituating' stimulus has decayed prior to re-presentation of the habituating stimulus, skin conductance response (SCR) amplitude to the habituating stimulus will not differ from that displayed by a control group which did not receive presentation of the 'dishabituating' stimulus. In experiment 1 (N = 10), subjects received 13 presentations of a 1000 Hz, 70 dB tone of 3 sec duration with interstimulus intervals of 40, 50 and 60 sec. Between trials 11 and 12, there was one presentation of a dishabituating (light) stimulus. Analysis of SCL indicated that an interval of 50 sec between trials 12 and 13 was sufficient to allow sensitization to decline to the pre-light level. The experimental conditions in experiment 2 (N = 32) were the same as in experiment 1 except that only half the subjects received presentation of the dishabituating stimulus. The results indicated that although there were no group differences in SCR amplitude on trials 1-11, experimental subjects displayed significantly larger responses on trial 13 than did control subjects. These results suggest that interpolation of a different stimulus in an habituation series does, in fact, disrupt the habituation process.