title: Timed excitatory conditioning under zero and negative contingencies.
abstract: Rats (rattus norvegicus) anticipated the arrival of a food pellet unconditioned stimulus (US) even when the conditioned stimulus (CS) signaled no overall change or a substantial decrease in the overall rate of US occurrence. Pellet USs were scheduled probabilistically in the intertrial interval at either an equivalent rate (Experiment 1) or a four times higher rate (Experiments 2 and 3) than in the CS, which included one fixed-time target US. Conditioning has been said to involve learning "whether" (contingency) the CS signals a change in the US, and if so, "when" (contiguity) the US is scheduled to arrive. Our results suggest that "when" trumps "whether," challenging the received view that a positive CS-US contingency is necessary for successful conditioning.
authors.affiliation: Psychology Department, University of Winnipeg, Manitoba, Canada. d.williams@uwinnipeg.ca
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Williams
authors.forename: Carla
authors.initials: C
authors.lastname: Lawson
authors.forename: Rachel
authors.initials: R
authors.lastname: Cook
authors.forename: Amber A
authors.initials: AA
authors.lastname: Mather
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Johns
mesh_terms: D000818:Animals; D003213:Conditioning, Psychological; D008297:Male; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time; D013998:Time Perception