Evidence for post-decisional conflict monitoring in delay discounting

Choice impulsivity can be measured by offering a sequence of various binary choices between smaller, immediately available rewards and larger, later available rewards. An individual's delay discount (DD) rate reflects the aggregate decision-making tendency. Given the broad spectrum of disorders associated with a high DD rate, this may be an important transdiagnostic factor. This study aimed to establish whether post-decisional neurophysiological processes reflecting the presence of error monitoring are involved in delay discounting. A large sample (N = 97) was investigated, including 46 females and 51 males. The electroencephalogram (EEG) was recorded during the classic monetary choice questionnaire (MCQ-27). Error-related event-related potentials (ERPs) and event-related oscillations (EROs) following responses were analyzed. A modest relationship between error positivity (Pe) and DD rate was seen centro-parietal, with higher amplitude for low DD individuals after choosing immediate rewards. A robust association was found between DD rate and theta oscillation power increases. This was most prominent in low DD individuals after making an immediate reward choice. Theta power was positively associated with decision (reaction) time, suggesting an association between pre- and post-decisional conflict. No evidence was found for an error-related negativity (ERN) and delta oscillations. This study provides clear evidence for conflict monitoring as a post-decision process in delay discounting. Findings suggest that diminished theta band power bursts and lower Pe amplitude, observed after choosing an immediate reward, reflect the neurophysiological consequence and possibly the cause of steep delay discounting. High DD was characterized by prefrontal hypoactivation and appears to result from affective decision-making.