Generalization and discrimination as a function of the S-D-S delta intensity difference

Three groups of four rats were trained on an auditory-intensity discrimination for 21 days. The S(D)-S(Delta) 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(Delta)'s which were presented intermingled with the original S(D) and S(Delta) values.

(1.) The amount of simple discrimination training required to obtain fairly stable differences in S(D) and S(Delta) responding is an inverse function of the magnitude of the stimulus difference between S(D) and S(Delta). (2.) Generalization gradients obtained immediately following simple discrimination training exhibit a maximum displaced from S(D) in a direction also away from S(Delta). (3.) Gradients obtained following continued exposure to the multivalued S(Delta) 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(Delta) limb of the gradient.