Generalization and discrimination as a function of the SD — SΔ intensity difference

Three groups of four rats were trained on an auditory-intensity discrimination for 21 days. The S^D-S^Δ intensity difference for Group I was 10 db; for Group II, 20 db; and for Group III, 30 db. Following the initial discrimination training, the animals were tested for generalization of the bar-press response to seven novel S^Δ's which were presented intermingled with the original S^D and S^Δ values. Conclusions: (1.) The amount of simple discrimination training required to obtain fairly stable differences in S^D and S^Δ responding is an inverse function of the magnitude of the stimulus difference between S^D and S^Δ. (2.) Generalization gradients obtained immediately following simple discrimination training exhibit a maximum displaced from S^D in a direction also away from S^Δ. (3.) Gradients obtained following continued exposure to the multivalued S^Δ situation show a fairly stable maximum at the S^D value. (4.) Although the gradients tend to fall off systematically on either side of the continuum as distance from S^D is increased, they decrease most rapidly on the S^Δ limb of the gradient.