Part-whole bias in intertemporal choice: An empirical study of additive assumption

Additive assumption means the overall value of multiple-dated outcomes is based on a simple aggregation of the values of each individual outcome. This assumption is generally accepted in the field of intertemporal choices. However, recent studies show additive assumption is questionable. In this paper, we experimentally tested the additive property of multiple-dated monetary rewards. Our results show: (1) additive assumption does not hold regardless of gain or loss; (2) the sum of subjective values of individual rewards is consistently larger than the valuation placed on the same rewards as a whole. This finding suggests that part-whole bias exists in the context of valuation of intertemporal monetary rewards.