Abstract: This study examined the strategies participants used to make preference choices in past temporal discounting tasks. The research participants included 33 healthy Chinese college students. Ten past temporal distances, from two weeks to 50 years, were chosen. After completing the experiment task in the delay paradigm, a questionnaire survey assessed the strategies participants used to make preference decisions. This study examined the strategies participants used to make preference choices in past temporal discounting tasks. The subjects included 33 college students. Ten past temporal distances, from two weeks to 50 years, were chosen. After completing the experiment task in the delay paradigm, a questionnaire survey assessed the strategies participants used to make preference decisions. Indifference points were calculated into the rate of past temporal discounting using UAUr(t1,t2). The content analysis of the questionnaire responses revealed that the anticipated benefit of past rewards in the present contributed to the changed rate of past temporal discounting, which caused the dominant strategies to change with increasing past temporal distance.

Key words: past temporal discounting, strategies, UAUr(t1,t2), recent past, modestly distant past, extremely distant past

摘要： 对过去事件的加工涉及到对现在信息的加工，过去获得的价值能够为现在的生活带来的收益可能对过去事件的价值估计具有影响。本研究探讨了过去事件对现在生活的影响在过去时间贴现中的作用。采用延迟时间贴现范式任务，选取2周到50年共10个过去时间长度，要求被试在现在获得的奖金和过去获得的奖金之间进行偏好选择，并且完成对过去时间贴现决策策略的问题回答。采用曲线下的单位面积UAUr(t1,t1) 为过去时间贴现率，发现过去时间贴现率在过去2周和过去1个月之间[Z = 2.662，p = .008]、过去1年和过去3年之间[Z = 2.587, p = .010] 差异显著。对决策策略的回答进行内容分析(频次统计信度为0.875)，发现过去事件能够为现在生活带来的收益影响了被试对过去事件的价值估计和偏好选择。从现在起到过去2周内，被试看重近的过去获得的奖金对现在的生活的帮助，偏好选择过去获得的奖金；在较远的过去，从过去2周起到过去1年内，奖金数量和获得奖金的时间之间的比例影响了被试的偏好选择；从过去1年起到过去50年内，远的过去获得的奖金对现在生活的影响微乎其微，被试偏好现在获得的奖金。本研究的结果支持了过去时间贴现和未来时间贴现具有不同的心理加工机制，并且有助于进一步了解过去时间的差别感受性的变化规律。

关键词: past temporal discounting, strategies, UAUr(t1,t2), recent past, modestly distant past, extremely distant past