大河内 浩人

Abstract Three pigeon dyads were exposed to a two‐component multiple schedule comprised of two tandem variable‐interval 30‐s interresponse time (IRT) > 3‐s schedules in the presence of different stimuli. Pecks to keys by both pigeons of a dyad occurring within 500 ms of one another were required for reinforcement under one tandem schedule (the coordination component), and such coordinated responses were not required under the other (the control component). The terminal link of each schedule ensured that the reinforced coordination response was an IRT > 3 s. Rates of coordinated IRTs > 3 s and total rates of coordinated responses (composed of IRTs > 3 s and IRTs ≤ 3 s) were higher in the coordination components than in either of two different control components in which coordination was not required for reinforcement. This difference in coordinated responses in the presence and absence of the coordination requirement under stimulus control transitorily deteriorated and then was reestablished when the relation between the stimulus and the coordination contingency or its absence was reversed. The results show coordinated responding to function as a discriminated social operant.

Abstract Although hypothetical rewards have been used almost exclusively in human discounting studies, investigations of their validity are limited. The present experiment compared the discounting of monetary reward value by probability across conditions in which the rewards were real, potentially real, and hypothetical. Twenty‐four undergraduates choose between an uncertain large reward and a certain small reward 60 times (trials). In the real and hypothetical reward conditions, the participants made choices with real and hypothetical money, respectively, in every trial. In the potentially real condition, they did so with real money in randomly selected three of the 60 trials and with hypothetical money in the remainder. The log₁₀‐transformed h values of a hyperbolic probability‐discount function and the values of the area under the curve with an ordinal transformation of odds against were higher and lower, respectively, in the potentially real and in the hypothetical reward conditions than in the real reward condition, demonstrating that the probability discounting of hypothetical monetary rewards was larger than that of real rewards. These results suggest that future studies are required to identify why the hypothetical reward procedure overestimates the discounting rates of real rewards.