Experimental studies on self-control and risky choice

本研究考察了人类和动物在自我控制和风险选择情境中的选择行为，其中增强剂数量和增强剂延迟或增强剂概率分别或同时变化，以考察增强剂延迟和增强剂概率在选择情境中是否具有功能等价性。结果表明，在自我控制选择情境中，人类对增强剂数量比增强剂延迟更敏感，他们的选择在定性意义上由增强剂的总体密度描述，而不是广义匹配定律所表示的局部增强剂密度。此外，以老鼠为研究对象的结果表明，在风险选择情境中，当能量收支状况(由其体重定义)为负时，老鼠更喜欢可变食物而不是恒定食物，而当能量收支状况为正时，它们更喜欢恒定食物；也就是说，它们根据自己的体重表现出风险厌恶或风险倾向。在另一种风险选择的情况下，研究发现，老鼠对确定的、延迟的和不确定的、延迟的较少的增强剂漠不关心。这一发现清楚地表明，在当前的选择情况下，增强剂延迟和概率的功能等价性是成立的。鸽子的选择是在增强剂的数量和概率分别或一起变化的情况下进行检查的。其结果是，他们的选择在定性意义上与广义匹配规律的预测是一致的，综合起来，似乎可以将概率转换为延迟区间，从而将有风险的选择情景简化为像自我控制选择情景一样，增强剂数量和延迟都不同的情况。

The present study investigated humans'and animals'choices in self-control and risky choice situations, in which reinforcer amounts and reinforcer delays or reinforcement probability were varied separately or together, to see whether a functional equivalence of reinforcer delay and probability can hold in a choice situation.The present results with human subjects showed that in a self-control choice situation, humans were more sensitive to reinforcer amount than to delay, and their choices were, in a qualitative sense, described by the overall density of reinforcement rather than the local density of reinforcement as represented by the generalized matching law. Further, the results with rats as subjects showed that in a risky choice situation, rats preferred a variable food over a constant food when the energy budget condition (defined by their body weights) was negative, whereas they preferred the constant food over the variable food when it was positive ; that is, they showed "risk aversion" or "risk proneness" depending on their body weights. In another risky choice situation, it was found that rats were indifferent between certain, more delayd and uncertain, less delayd reinforcers. This finding clearly indicate that a functional equivalence of reinforcer delay and probability can hold in the present choice situation. Pigeons'choices were examined in situations where reinforcer amount and probability were varied separately or together. As a result, their choices were, in a qualitative sense, consisitent with predictions from the generalized matching law.Taken together, it seems that probability can be transformed to delay intervals, thereby a risky choice situation may be reduced to the situation where reinforcer amount and delay are varied as in a self-control choice situation.