Eye Movement Analysis of Time Discounting

抄録

This paper reveals the process of solving a time discounting task with eye tracking. There is a hypothesis that time discounting anomalies such as present bias result not from calculating present discount values of smaller-earlier and larger-later rewards, but from separately comparing attributes such as the timing of receipts and the amounts of rewards. However, our eye movement data show that the proportion of saccades when comparing each option holistically, which implies subjects calculate present discount values, is significant large and is nearly equal to that of saccades when comparing attributes separately. The saccade comparing an earlier option holistically is initially a high likelihood, and then the saccades gradually combine the saccades comparing each option holistically with the saccades comparing attributes separately at the same likelihood. Combining our experimental results and previous research, we support the attention-focusing hypothesis, which implies that when the timing of receipts is written as a delay, subjects are more prone to calculate the discounting rate than when it is written as a date.