title: Willing to wait: Elevated reward-processing EEG activity associated with a greater preference for larger-but-delayed rewards.
abstract: While almost everyone discounts the value of future rewards over immediate rewards, people differ in their so-called delay-discounting. One of the several factors that may explain individual differences in delay-discounting is reward-processing. To study individual-differences in reward-processing, however, one needs to consider the heterogeneity of neural-activity at each reward-processing stage. Here using EEG, we separated reward-related neural activity into distinct reward-anticipation and reward-outcome stages using time-frequency characteristics. Thirty-seven individuals first completed a behavioral delay-discounting task. Then reward-processing EEG activity was assessed using a separate reward-learning task, called a reward time-estimation task. During this EEG task, participants were instructed to estimate time duration and were provided performance feedback on a trial-by-trial basis. Participants received monetary-reward for accurate-performance on Reward trials, but not on No-Reward trials. Reward trials, relative to No-Reward trials, enhanced EEG activity during both reward-anticipation (including, cued-locked delta power during cue-evaluation and pre-feedback alpha suppression during feedback-anticipation) and reward-outcome (including, feedback-locked delta, theta and beta power) stages. Moreover, all of these EEG indices correlated with behavioral performance in the time-estimation task, suggesting their essential roles in learning and adjusting performance to maximize winnings in a reward-learning situation. Importantly, enhanced EEG power during Reward trials, as reflected by stronger 1) pre-feedback alpha suppression, 2) feedback-locked theta and 3) feedback-locked beta, was associated with a greater preference for larger-but-delayed rewards in a separate, behavioral delay-discounting task. Results highlight the association between a stronger preference toward larger-but-delayed rewards and enhanced reward-processing. Moreover, our reward-processing EEG indices detail the specific stages of reward-processing where these associations occur.
authors.affiliation: Department of Psychology, Northwestern University, Evanston, IL, United States; Department of Psychology, University of Singapore, Singapore. Electronic address: nonnarun@u.northwestern.edu.
authors.forename: Narun
authors.initials: N
authors.lastname: Pornpattananangkul
authors.affiliation: Department of Psychology, Northwestern University, Evanston, IL, United States.
authors.forename: Robin
authors.initials: R
authors.lastname: Nusslock
mesh_terms: D059031:Anticipation, Psychological / Q000502:physiology; D001921:Brain / Q000502:physiology*; D003463:Cues; D065786:Delay Discounting / Q000502:physiology*; D004569:Electroencephalography; D030141:Feedback, Psychological / Q000502:physiology; D005260:Female; D006801:Humans; D007206:Individuality; D008297:Male; D009042:Motivation / Q000502:physiology; D009483:Neuropsychological Tests; D012201:Reward; D055815:Young Adult
keywords: Delay discounting; Feedback-locked beta; Frontal midline theta; Pre-stimulus alpha suppression; Reward-processing