Department of Psychology, University of South Dakota, Vermillion, SD 57069, USA.
Psychol Sci. 2010 Feb;21(2):183-8. doi: 10.1177/0956797609358096. Epub 2010 Jan 20.
This study explored metabolic mechanisms of future (delay) discounting, a choice phenomenon where people value present goods over future goods. Using fluctuating blood glucose as an index of body-energy budget, optimal discounting should regulate choice among rewards as a function of temporal caloric requirement. We identified this novel link between blood glucose levels measured in the lab and future-discounting rates of participants, who made choices between a "smaller and sooner" reward and a "larger but later" option, with possible actual monetary rewards. A group of participants who drank a soft drink that contained sugar showed a reduced rate of future discounting afterward, when we controlled for sex, age, body mass index, and the taste of the drink. In contrast, a group of participants who drank a soft drink that contained artificial sweetener showed an increased rate of future discounting. Blood glucose levels not only varied as a result of caloric intake but also regulated the rate of future discounting, according to participants' dynamic body-energy budget.
本研究探讨了未来（延迟）折扣的代谢机制，这是一种人们更看重当前商品而不是未来商品的选择现象。本研究使用波动的血糖作为身体能量预算的指标，认为最优折扣应根据时间热量需求调节奖励之间的选择。我们发现了血糖水平与参与者未来折扣率之间的这种新联系，参与者在一个“小而快”的奖励和一个“大而慢”的选项之间做出选择，选项中可能有实际的金钱奖励。一组喝含糖软饮料的参与者在控制了性别、年龄、体重指数和饮料味道后，表现出未来折扣率降低的情况。相比之下，一组喝含有人工甜味剂软饮料的参与者表现出未来折扣率增加的情况。根据参与者的动态身体能量预算，血糖水平不仅会因热量摄入而变化，还会调节未来折扣率。
