We re-examine behavioral patterns of intertemporal choice with recognition that time preferences may be inherently variable, focusing in particular on the explanatory power of an exponential discounting model with variable discount factors - the variable exponential model. We provide analytical results showing that this model can generate systematically different choice patterns from an exponential discounting model with a fixed discount factor. The variable exponential model accounts for the common behavioral pattern of decreasing impatience, which is typically attributed to hyperbolic discounting. The variable exponential model also generates violations of strong stochastic transitivity in choices involving intertemporal dominance. We present the results of two experiments designed to evaluate the variable exponential model in terms of quantitative fit to individual-level choice data. Data from these experiments reveal that allowing for a variable discount factor significantly improves the fit of the exponential model, and that a variable exponential model provides a better account of individual-level choice probabilities than hyperbolic discounting models. In a third experiment we find evidence of strong stochastic transitivity violations when intertemporal dominance is involved, in accordance with the variable exponential model. Overall, our analytical and experimental results indicate that exponential discounting can explain intertemporal choice behavior that was supposed to be beyond its descriptive scope if the discount factor is permitted to vary at random. Our results also highlight the importance of allowing for different sources of randomness in choice modeling.

中文翻译：

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可变时间偏好

我们重新审视跨期选择的行为模式，认识到时间偏好可能是固有可变的，特别关注具有可变折扣因子的指数折扣模型的解释能力——可变指数模型。我们提供的分析结果表明，该模型可以从具有固定折扣因子的指数折扣模型系统地生成不同的选择模式。可变指数模型解释了减少不耐烦的常见行为模式，这通常归因于双曲线贴现。可变指数模型也会在涉及跨期支配的选择中产生对强随机传递性的违反。我们展示了两个实验的结果，这些实验旨在评估变量指数模型对个体水平选择数据的定量拟合。这些实验的数据表明，允许可变折扣因子显着提高了指数模型的拟合度，并且与双曲线折扣模型相比，可变指数模型可以更好地说明个人层面的选择概率。在第三个实验中，根据可变指数模型，当涉及跨期优势时，我们发现了强随机传递性违规的证据。总体而言，我们的分析和实验结果表明，如果允许折扣因子随机变化，指数折扣可以解释本应超出其描述范围的跨期选择行为。