Emotional arousal predicts intertemporal choice

Abstract

People generally prefer immediate rewards to rewards received after a delay, often even when the delayed reward is larger. This phenomenon is known as temporal discounting. It has been suggested that preferences for immediate rewards may be due to their being more concrete than delayed rewards. This concreteness may evoke an enhanced emotional response. Indeed, manipulating the representation of a future reward to make it more concrete has been shown to heighten the reward's subjective emotional intensity, making people more likely to choose it. Here the authors use an objective measure of arousal-pupil dilation-to investigate if emotional arousal mediates the influence of delayed reward concreteness on choice. They recorded pupil dilation responses while participants made choices between immediate and delayed rewards. They manipulated concreteness through time interval framing: delayed rewards were presented either with the date on which they would be received (e.g., "$30, May 3"; DATE condition, more concrete) or in terms of delay to receipt (e.g., "$30, 7 days; DAYS condition, less concrete). Contrary to prior work, participants were not overall more patient in the DATE condition. However, there was individual variability in response to time framing, and this variability was predicted by differences in pupil dilation between conditions. Emotional arousal increased as the subjective value of delayed rewards increased, and predicted choice of the delayed reward on each trial. This study advances our understanding of the role of emotion in temporal discounting. (PsycINFO Database Record

Figure 1. Task Layout

Each trial began with a fixation cross (1 sec), followed by display of an immediate reward option (4 sec). Then a delayed reward option was shown (4 sec). For half of the trials, it was presented with the date on which it would be received, while for the other half, it was presented with the number of days until reward receipt. Individuals made a button press while the word “Choice?” was presented on the screen following delayed reward presentation (3 sec). After another fixation cross (2.5 sec), they were shown the option that they chose on that trial (3 sec).

Figure 2. Individual differences in response to DATE/DAYS manipulation

Each bar represents the difference in log-transformed discount rate between the DATE and DAYS condition for each subject (N = 51). White bars represent subjects who were more patient (i.e., had a lower discount rate) in the DATE condition; black bars represent subjects who were more patient in the DAYS condition. Asterisks indicate subjects that showed a significant difference in discount rate between the two conditions, as determined by likelihood ratio tests (*p < 0.05).

Figure 3. Results of general linear model analysis of the pupil dilation response during delayed reward presentation

A) Value Model. Average of best-fitting beta weights for the delayed reward presentation, and delayed reward presentation parametrically modulated by RVE (relative value equivalence: the negative of the absolute difference between the subjective values of the immediate and delayed reward options), DATE/DAYS (−1 = DAYS; 1 = DATE), and subjective value of the delayed reward. B) Choice Model. Average of best-fitting beta weights for the delayed reward presentation, and delayed reward presentation parametrically modulated by DATE/DAYS (−1 = DAYS; 1 = DATE), and choice (1 = delayed reward chosen; −1 = immediate reward chosen). Error bars represent 95% CIs (* p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001).

Figure 4. Individual differences in pupil response predict individual differences in response to DATE/DAYS manipulation

Scatterplot showing relationship between difference in log-transformed discount rate between the DATE and DAYS condition for each subject (N = 51) and difference in average pupil dilation response between the DATE and DAYS condition. Pupil dilation response was defined as the average baseline-corrected pupil diameter from 1 sec – 4 sec following delayed reward onset.