Using an extension of the blocking paradigm, the question of whether operations that reduce the associability of a stimulus (preexposure, redundancy) exert their effects independently of the context in which they are experienced was examined. Prior to conditioning two of the four groups received 20 presentations (4/day for 5 days) of a visual stimulus prior to its use as a redundant element in the blocking paradigm. Preexposure occurred in the same context as the training situation for one of the groups; the other group experienced the stimulus in an altered auditory, visual and olfactory environment. The other groups served as controls: one received the blocking regimen; the other served as an overshadowing control. An altered context during preexposure enhanced the associability of the redundant cue evidenced by an attenuation of blocking. This finding suggests that one indirect effect of context is the specification of a conditional relationship between stimulus and response such that operations which alter the associability of a stimulus are dependent upon the context in which they occur.
The effects of nonreinforced and randomly reinforced stimulus preexposure on conditioned suppression in rats
