Twelve undergraduates in four groups responded by clicking on a button presented on a computer screen. Participants of Groups 1 and 3 were exposed to the sequence FR - DRL - FI and those of Groups 2 and 4 to the sequence DRL - FR - FI. Reinforcers were points exchanged by money (Groups 1 and 2) or points only (Groups 3 and 4). Effects of recent histories over FI performance were consistently observed when points were exchanged by money. DRL histories, recent or remote, affected subsequent performance especially when reinforcers were points only. Results suggest that the reinforcer that is used modulates history effects over FI performance and that its manipulation can clarify some discrepancies between human and non-human in schedules of reinforcement.
schedules of reinforcement; behavioral history; type of reinforcer; humans
