Four undergraduates were exposed to a fixed-ratio schedule under an instruction to respond slowly and to a differential-reinforcement-of-low-rate 5-s schedule under an instruction to respond rapidly. Following this, a fixed-interval schedule was in effect under those same two sets of instructions. For 3 of 4 subjects, response rates were higher with the instruction to respond slowly than with the instruction to respond rapidly during the fixed-interval schedule. For the remaining subject, lowrate responding with the instruction to respond rapidly continued during the first 17 reinforcements of the fixed-interval schedule. Such control by instructions was not observed for other subjects exposed only to a fixed-interval schedule, with or without instructions. The results demonstrate that the effect of instructions can be altered by contingencies and suggest that instructions can function as discriminative stimuli.

Abstract:The relation between reformative self-control and discounting of reward value by delay or effort was examined. Thirty-two Japanese undergraduates were selected based on their scores on a standardized pencil and paper test of self-control, the RedressiveReformative Self-Control Scale (Sugiwaka, 1995). The subjects indicated their preference (i) between a hypothetical 100 000 yen reward available with various delays and a certain reward of variable amount available immediately; or (ii) between a hypothetical 100 000 yen reward available with various efforts and a certain reward of variable amount available without effort. The discounting of delayed reward value was described well by a hyperbolic function proposed by Mazur (1987). The slopes of the delayed discounting curves were steeper for subjects who scored low on the Reformative Self-Control Scale, which is a measure of reformative self-control and a subscale of the Redressive-Reformative SelfControl Scale. The discounting by effort was also described well by the hyperbolic function. The slopes of the effortful discounting curves did not correlate to those of the delayed discounting curves. The slopes were not systematically different across the groups of subjects with different scores on the reformative self-control scale.

Undergraduates were exposed to a mixed fixed-ratio differential-reinforcement-of-low-rate schedule. Values of the schedule components were adjusted so that interreinforcer intervals in one component were longer than those in another component. Following this, a mixed fixed-interval 5-s fixed-interval 20-s schedule (Experiment 1) or six fixed-interval schedules in which the values ranged from 5 to 40 s (Experiment 2) were in effect. In both experiments, response rates under the fixed-interval schedules were higher when the interreinforcer intervals approximated those produced under the fixed-ratio schedule, whereas the rates were lower when the interreinforcer intervals approximated those produced under the different-reinforcement-of-low-rate schedule. The present results demonstrate that the effects of behavioral history were under control of the interreinforcer intervals as discriminative stimuli.

One group of undergraduates responded under a fixedratio (FR) 25 schedule and a second group responded under a differential-reinforcement-of-low-rate (DRL) 5-s schedule (first history phase). Both groups of subjects were then exposed to a differential-reinforcement-of-other-behavior (DRO) 5-s schedule (second history phase), and finally to fixed-interval (Fi) 5-s (Experiment 1), variable-interval (Vi) 5-s (Experiment 2), extinction, FR, and DRL (Experiment 3) schedules (history testing phase). Response rates under the extinction and the FR schedule in the history-testing phase were higher for subjects with a history of the FR schedule than for subjects with a DRL history. Such a systematic difference by remote histories was not observed when the Fi, Vi, and DRL schedules were in effect during testing.

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