title: Discrimination between outcomes in instrumental learning: effects of preexposure to the reinforcers.
abstract: In two experiments rats received instrumental training with two response levers, one response being reinforced by sucrose solution and the other by sucrose pellets. Prior to a test session, on which both levers were made available in the absence of reinforcement, the rats were given free access to one of the reinforcers, a procedure known to reduce its value. It was found that the rats responded at a lower rate on the lever that had produced the now-devalued reinforcer, but that this effect was substantial only in rats that had received preexposure to the two reinforcers before instrumental training was begun (Experiment 1). Experiment 2 demonstrated that this effect was obtained only when presentations of the two reinforcers were presented according to an inter-mixed schedule during preexposure. It is suggested that this result constitutes an instance of the perceptual learning effect in which intermixed preexposure to similar events enhances their discriminability.
authors.affiliation: University of York, York, UK.
authors.forename: C A J
authors.initials: CA
authors.lastname: Blair
authors.forename: Pam
authors.initials: P
authors.lastname: Blundell
authors.forename: Tiffany
authors.initials: T
authors.lastname: Galtress
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Hall
authors.forename: Simon
authors.initials: S
authors.lastname: Killcross
mesh_terms: D000818:Animals; D003216:Conditioning, Operant / Q000502:physiology*; D004193:Discrimination Learning / Q000502:physiology*; D005108:Extinction, Psychological / Q000502:physiology; D005795:Generalization, Stimulus / Q000502:physiology; D007266:Inhibition, Psychological; D008297:Male; D010865:Pilot Projects; D051381:Rats; D011919:Rats, Inbred Strains; D021641:Recognition, Psychology / Q000502:physiology*; D012054:Reinforcement, Psychology; D012528:Satiety Response / Q000502:physiology