The strength of the orienting response during blocking.

Abstract

In two experiments rats initially received appetitive Pavlovian conditioning with an auditory conditioned stimulus (CS). Subsequently this stimulus was presented in compound with a novel light and paired with the same appetitive reinforcer. In keeping with the outcome of many such experiments on blocking, there was very little evidence of appetitive conditioning during subsequent independent presentations of the light. Of main concern in the present experiments, however, was the influence of this training on the strength of the orienting response directed towards the light. When the light was first presented it elicited a strong orienting response. The strength of this response declined rapidly when the light was presented in compound with the previously trained auditory CS but more slowly when it was paired with the reinforcer either by itself or in conjunction with an initially neutral auditory stimulus. It is suggested that the extent to which the events following the light are accurately predicted determines the strength of orientation towards this stimulus.