CS Intensity effects on rabbit nictitating membrane conditioning,extinction and generalization

One purpose of the present experiments was to determine if the Grice and Hunter (1964) observation of augmented within-versus between-Ss CS intensity effects in human eyelid conditioning would be obtained in conditioning of the rabbit’s nictitating membrane response under two (Experiment 1) and four (Experiment 2) CS intensity values. In addition, a determination was made of the effects of CS intensity upon extinction and stimulus intensity generalization gradients. The studies revealed that: (a) while acquisition performance was positively related to CS intensity, the effect was independent of the between and within-S manipulation of CS intensity; (b) rate of response decrement in extinction was an inverse function of CS intensity; and (c) a positively sloped intensity generalization gradient was obtained when the training stimulus was the low-intensity one. Overall, these results are most consistent with Hull’s (1949) stimulus intensity dynamism account of CS intensity effects in conditioning.