title: Reinforcement omission in concurrent fixed-interval and random-interval schedules.
abstract: The present experiment examined overall and local effects of omission of reinforcers in a choice situation. Pigeons' key-pecking responses were reinforced under concurrent fixed-interval and random-interval schedules of food presentation. After some weeks of baseline sessions in which the probability of reinforcement was 1.00, approximately 25% of food presentations from the fixed-interval schedule were omitted and replaced by timeout periods. In such omission sessions, the overall relative rates of responding to the fixed-interval schedule became lower than those in the baseline sessions. On the other hand, when relative rates of responding to the fixed-interval schedule in the omission sessions were calculated separately for fixed-interval cycles preceded by timeout periods and those preceded by food presentations, the relative rates in the former type of fixed-interval cycles were higher than those in the latter type for three out of four pigeons. These results mean that relative rates of responding cannot always be regarded as reflecting a relative value of an alternative, and that the overall effect of the omission of fixed-interval reinforcers is not reducible to the local effect of omission.
authors.affiliation: Centre for Integrated Research on the Mind, Keio University, 3-1-7 Mita-Toho Bldg. 7F, Mita, Minato-ku, Tokyo 108-8345, Japan. ishii@psy.flet.keio.ac.jp
authors.forename: Taku
authors.initials: T
authors.lastname: Ishii
authors.forename: Takayuki
authors.initials: T
authors.lastname: Sakagami
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002755:Choice Behavior / Q000502:physiology*; D010856:Columbidae; D003216:Conditioning, Operant / Q000502:physiology; D012055:Reinforcement Schedule; D012201:Reward; D012718:Set, Psychology; D013998:Time Perception / Q000502:physiology*