Enhancing tolerance to delayed reinforcers: the role of intervening activities.

Three participants with moderate to profound mental retardation were exposed to choices between an immediate small amount and a delayed larger amount of a preferred reinforcer. All participants initially showed a relatively high preference for the smaller reinforcer, suggesting impulsive choice making. However this preference reversed, suggesting self-control, when the larger reinforcer was available immediately and, over time, its delay was gradually increased. Results highlight the potential utility of incorporating concurrent activities into self-control training paradigms.