Fixed Attributes and Discounting Behavior Effects of Holding One Attribute Constant During an Intertemporal Choice Task

Delay discounting tasks present alternatives that differ in two attributes: amount and delay. Typically, choice is modeled by application of a discount function to each option, allowing alternative-wise comparison. However, if participants make decisions by comparing attributes, manipulations that affect the salience of either attribute may affect patience. In Experiment 1, participants completed one block of trials in which amount was a fixed attribute (constant across trials), and another in which delay was fixed. Consistent with the hypothesis that the varying attribute would be more salient, participants exhibited less patience in the amount-fixed condition. Moreover, this effect was larger for participants who responded more quickly when making choices that favored the varying attribute. In Experiment 2, these findings were extended by adding trial blocks with a working memory dual task. We replicated the fixed-attribute effect, along with the aforementioned association with reaction time. Contrary to expectation, the fixed-attribute effect was not larger when participants were under working memory load. Instead, working memory load was associated with more patient responses, which may be related to idiosyncrasies of the task including the absence of immediate rewards. Overall, results suggest a fixed-attribute effect on patience, which is consistent with a multi-attribute decision framework.