Further observations on the incremental stimulus intensity effect and habituation of the human electrodermal response

Two studies are reported which examined the relative effectiveness of an incremental series of stimulus intensities for reducing electrodermal responsiveness to a test stimulus. In the first study, employing five pairs of male undergraduates matched on electrodermal responsiveness, habituation to a 100 db (re 20muN/m2) noise burst was compared following two training procedures. In one, stimulation began at 64 db and increased by 4 db up to 96 db whenever two consecutive presentations of the stimulus failed to elicit a response. In the other, an equivalent number of presentations with a 100 db noise burst were provided. While habituation occurred during both training conditions, subsequent habituation to a 100 db test stimulus was more rapid following incremental training. In the second experiment, employing 40 female undergraduates, incremental and fixed conditions of training were compared for effectiveness using more moderate intensities of test stimulus: viz., 60 db and 80 db. A these levels, the fixed training series was superior to the incremental in reducing responsiveness. The data extend previous findings on the incremental stimulus intensity effect with the human electrodermal response but suggest limiting conditions for its demonstration.