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10.35430/nab.2020.e13Neuroanatomy and Behaviour2e1

The Partial-Reinforcement Extinction Effect Does Not Result from Reduced Sensitivity to Non-Reinforcement

Five experiments used a magazine approach paradigm with rats to investigate whether learning about non-reinforcement is impaired in the presence of a conditioned stimulus (CS) that had been partially reinforced (PRf). Experiment 1 trained rats with a PRf CS and a continuously reinforced (CRf) CS, then extinguished responding to both CSs presented together as a compound. Probe trials of each CS presented alone revealed that extinction was slower for the PRf CS than the CRf CS, despite being extinguished in compound. In Experiment 2, a CRf light was extinguished in compound with either a CRf CS or a PRf CS that had been matched for overall reinforcement rate. Responding to the light extinguished at the same rate regardless of the reinforcement schedule of the other CS. Experiment 3 replicated this result with a PRf light. Thus, we found no evidence that a PRf CS impairs extinction of another CS presented at the same time. Experiments 4 and 5 extended this approach to study the acquisition of conditioned inhibition by training an inhibitor in compound with either a PRf or CRf excitatory CS. The reinforcement schedule of the excitatory CS had no effect on the acquisition of inhibition. In sum, conditioning with a PRf schedule slows subsequent extinction of that CS but does not affect learning about the non-reinforcement of other stimuli presented at the same time. We conclude that the Partial Reinforcement Extinction Effect is not due to a decrease in sensitivity to non-reinforcement following presentation of a PRf CS