| Abstract: | In two experiments with rats, three stimuli, A, B, and X, were used for an AX+ BX+ Xo discrimination in which food was presented after the simultaneous presentation of A and X, or B and X, but never after X by itself. For one group in each experiment, X was repeatedly presented by itself before the start of discrimination training. This manipulation weakened responding on test trials in which the three stimuli were presented together. The results are interpreted in terms of a configural theory of conditioning that assumes that preexposure to a stimulus will reduce its capacity to promote generalization among different configurations to which it belongs. |
