強制選択場面と自由選択場面の間の選択に及ぼす選択結果の不確実性の効果

抄録

Subjects usually prefer a free choice situation that consists of multiple alternatives to a compulsory situation that consists of a single alternative, even though all of these alternatives produce the same outcomes. However, some experiments showed that the free choice situation was not preferred when one of its alternatives provided inaccessible reinforcers because of very short reinforcement durations. We used as an aversive factor an alternative with uncertain (50%) reinforcement instead of a short duration. Seven pigeons were exposed to several conditions with concurrent-chains schedules. Under a condition where each of 2 alternatives in the free choice situation produced a certain (100%) or an uncertain outcome, 6 out of 7 subjects showed a strong preference for the compulsory choice situation when its single alternative produced a certain reinforcement. On the contrary, only 1 subject preferred the compulsory situation when its single alternative changed to provide certain and uncertain outcomes randomly. All of our results could be explained by comparing averaged values of reinforcers presented probabilistically in the free and the compulsory choice situations.