title: Choice between delayed reinforcers in an adjusting-delay schedule: the effects of absolute reinforcer size and deprivation level.
abstract: Choice between two reinforcers differing in magnitude and delay was investigated in rats using an adjusting-delay discrete-trials schedule in which the two reinforcers were associated with two levers (A and B). The delay to Reinforcer A (the smaller reinforcer) was always 2 sec, whereas the delay to Reinforcer B was varied in accordance with the distribution of choices in successive blocks of trials. In Experiment 1, the mean delay to the large reinforcer during the last 5 of 60 training sessions was greater when the rats were maintained at 80% than when they were maintained at 90% of their free-feeding body weights. In Experiment 2, the delay to the larger reinforcer was greater when the two reinforcers consisted of one and two 45-mg food pellets than when they consisted of three and six pellets. The results are consistent with a model of "self-control" which posits hyperbolic relations between reinforcer value and reinforcer magnitude, and between reinforcer value and delay of reinforcement.
authors.affiliation: Department of Psychiatry, University of Manchester, U.K.
authors.forename: M A
authors.initials: MA
authors.lastname: Wogar
authors.forename: C M
authors.initials: CM
authors.lastname: Bradshaw
authors.forename: E
authors.initials: E
authors.lastname: Szabadi
mesh_terms: D000818:Animals; D001070:Appetitive Behavior; D002755:Choice Behavior; D005260:Female; D005508:Food Deprivation; D009042:Motivation; D051381:Rats; D011919:Rats, Inbred Strains; D012055:Reinforcement Schedule