VARYING TEMPORAL PLACEMENT OF RESPONSE-PRODUCED STIMULI IN A FIXED-INTERVAL SCHEDULE

During a stimulus-available period (SAP) within a fixed-interval schedule of reinforcement (FI)y each response produced a distinctive key color change (response key color changed from white to green). The influence of the temporal placement of the SAP within the FI was determined for two pigeons. Responding was reduced during SAP for all placements. For early placements, responding was elevated just prior to SAP. For late placements of the SAP responding was suppressed just prior to relatively more than during the SAP. Data were related to Egger and Miller’s proposal that the first of a series of stimuli preceding reinforcement will be the stronger conditioned reinforcer. © 1969, Psychonomic Journals, Inc.. All rights reserved.