Effects of contingency violations on the extinction of a conditioned fear inhibitor and a conditioned fear excitor.
Rats were used in a conditioned-suppression paradigm to assess the effects of contingency variations on responding to a conditioned inhibitor (CS-) and a conditioned excitor (CS+). In Experiment 1, various unconditioned stimulus (US) frequencies were equated across the presence and absence of a CS- in the context of either background cues (continuous-trial procedure) or an explicit neutral event (discrete-trial procedure). With both procedures, a CS-alone treatment enhanced inhibition, whereas treatments involving 50% or 100% reinforcement for the CS- eliminated inhibition without conditioning excitation to that CS. The latter outcome also occurred in Experiment 2, with discrete-trial training equating considerably reduced US frequencies for the presence and absence of the CS-. In further evidence that inhibition was eliminated without conditioning excitation to the CS-, Experiment 3 showed that a novel CS did not acquire excitation when 25%, 50%, or 100% reinforcement was equated across the presence and absence of that CS in the context of a discrete-trial event. Using the procedures of Experiment 1, Experiment 4 showed that a CS+ was extinguished by a CS-alone treatment but was substantially maintained by treatments involving 50% or 100% uncorrelated reinforcement. These effects for a CS+ and a CS- implicate CS-US contiguity, rather than contingency, as the factor determining the extinction of a CS.
DeVito
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PL
Fowler
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D000818:Animals; D003214:Conditioning, Classical; D004597:Electroshock; D005108:Extinction, Psychological; D005239:Fear; D006185:Habituation, Psychophysiologic; D007266:Inhibition, Psychological; D008027:Light; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012055:Reinforcement Schedule; D013016:Sound; D014867:Water
D014867:Water