Response bias induced in rats by response effects.

Two experiments examined whether response choice in rats is affected by the presentation of response-produced stimuli. Rats were first trained to emit two different responses, with each response producing a unique auditory stimulus. Subsequently, the former response-produced stimuli were presented while the two response options were freely available. Presentation of a former response-produced stimulus caused the rats to choose more frequently the response option that had previously produced that specific stimulus over the other response option. However, although statistically significant, this response-biasing effect was numerically weak and was only apparent when the stimuli no longer had a general response-activating effect. Moreover, in the case of relatively short presentations of the stimuli, the response-biasing effect was only present if, during testing, the responses continued to produce the auditory stimuli according to the response-effect mapping used during training. These results were discussed in terms of possible underlying associations and were contrasted with previous results from analogous human studies on action control by response-produced stimuli.