关键词: 跨期选择, 时间知觉, 老化, 时间折扣/ 时间贴现, 折扣率

Abstract: Intertemporal choice is a decision-making process that involves tradeoffs between costs and benefits at different points in time. It has been a hot topic in multiple disciplines. However, it is much less known how intertemporal choice changes with the growth of age. A majority of studies found that older adults displayed more preference for delayed, bigger rewards over immediate, smaller rewards compared to younger adults. The current review mainly, but not exclusively, focuses on the way in which age-related differences in time perception impact intertemporal choice. First, subjective perception of time interval can explain multiple discounted-utility anomalies better than objective time interval. As we age, subjective time becomes faster, and degree of time compression becomes higher. There are several interpretations to the age-related changes in time perception. (1) The “internal clock” slows down when individuals age. (2) The occurrence rate of important or novel life events decrease with age. (3) Cognitive resources decrease with age, which constrains individuals’ capacity to monitor time. (4) Wealthy life experience in older adults also promotes the feeling that a certain interval is not so long. Second, previous studies have found that older adult perceived lower time cost than younger adults, which might cause their underestimation of the value of immediate rewards. There are several interpretations to this phenomenon. (1) Older adults’ wealthy life experience and knowledge help them reduce their inner uncertainties about life and make them more optimistic. (2) The deterioration of sensory function weakens the pleasure of getting immediate rewards and reduces the uncomfortableness in the process of waiting for delayed rewards. (3) Old adults regulate emotions more frequently and effectively, which helps them cope with negative emotions caused by delaying gratification. Third, the socioemotional selectivity theory (SST) asserts that people perceive their future life time incrementally decreases after they step into their later life, which results in a chronicle shift in their life goals. Specifically, younger adults prioritize future-oriented knowledge-seeking goals, while older adults increasingly prioritize present-oriented emotional goals. As a consequence, older adults develop better emotion-regulation abilities to fulfill their emotional goals. The shift in life goal and motivation resulting from age-related changes in time perception may contribute to better self-control of impulsivity, better skills in dealing with emotions, and higher levels of optimism among older adults, and thus making older adults more willing to wait for delayed rewards compared to younger adults. In short, time perception is an important factor that results in age-related changes in intertemporal choice. However, we also acknowledge that there are other factors which may dynamically and interactively influence younger and older adults’ intertemporal choices. Future research needs to figure out how these factors dynamically interact with each other.

Key words: intertemporal choice, time perception, aging, time discounting, discount rate