Extinction can be enhanced by a concurrent excitor.
Five experiments used rat subjects to investigate the impact on extinction of the presence of other conditioned stimuli. In Experiments 1 (Pavlovian magazine approach) and 2 (instrumental discriminative training), an excitatory stimulus (X) was extinguished alone, in conjunction with a previously reinforced other stimulus (A), in conjunction with previously nonreinforced other stimulus (B), or it was spared extinction. Responding during extinction was greatest to AX, and subsequent testing of X alone showed AX extinction to have produced the most decrement to X. Experiment 3 found similar results using a within-subject design. Experiment 5 continued separate reinforced presentations of A during extinction. This procedure not only promoted extinction of X but also converted it into a conditioned inhibitor. These experiments bear on the mechanisms of overshadowing and stimulus processing, as well as provide information on the determinants of extinction.
Department of Psychology, University of Pennsylvania, Philadelphia, USA. rescorla@cattell.psych.upenn.edu
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D000704:Analysis of Variance; D000818:Animals; D003214:Conditioning, Classical; D003216:Conditioning, Operant; D005108:Extinction, Psychological; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012054:Reinforcement, Psychology