title: Overshadowing as a function of trial number: dynamics of first- and second-order comparator effects.
abstract: In two conditioned lick suppression experiments with rats, we examined the permanence of the overshadowing effect as a function of the number of compound reinforced training trials. In Experiment 1, robust overshadowing was observed following 4 compound-US pairings but dissipated with 36 pairings. Overshadowing decreased because responding to the overshadowed stimulus increased, not because responding by the control group decreased. This dissipation was stimulus specific and not attributable to a response ceiling. Experiment 2 extended the generality of the effect to a sensory preconditioning design and further demonstrated that overshadowing lost through many compound-US pairings was restored by posttraining extinction of the training context. The results are explicable in terms of the extended comparator hypothesis (Denniston, Savastano, & Miller, 2001) under the assumption that the impacts of first- and second-order comparator processes grow differentially as a function of number of trials.
authors.affiliation: State University of New York, Binghamton, New York 13902-6000, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Stout
authors.forename: Francisco
authors.initials: F
authors.lastname: Arcediano
authors.forename: Martha
authors.initials: M
authors.lastname: Escobar
authors.forename: Ralph R
authors.initials: RR
authors.lastname: Miller
mesh_terms: D000818:Animals; D003213:Conditioning, Psychological; D003463:Cues; D004327:Drinking Behavior; D005260:Female; D006801:Humans; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors