Evidence for post-decisional conflict monitoring in delay discounting

Choice impulsivity can be measured by offering a sequence of various binary choicesbetween smaller, immediately available rewards and larger, later available rewards. Anindividual’s delay discount (DD) rate reflects the aggregate decision-making tendency. Giventhe broad spectrum of disorders associated with a high DD rate, this may be an importanttransdiagnostic factor. This study aimed to establish whether post-decisionalneurophysiological processes reflecting the presence of error monitoring are involved indelay discounting.A large sample (N=97) was investigated, including 46 females and 51 males. Theelectroencephalogram (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 andfor high DD individuals after choosing delayed rewards, respectively. A robust associationwas found between DD rate and theta oscillation power increases. This was most prominentin low DD individuals after making an immediate reward choice, showing activation of allelectrodes. No evidence was found for an error-related negativity (ERN) and response-relatedactivity in the delta oscillations.This study provides clear evidence for conflict monitoring as a post-decision processin delay discounting. Findings suggest that diminished theta band power bursts and lower Peamplitude, observed after choosing an immediate reward, reflect the neurophysiologicalconsequence and possibly the cause of steep delay discounting. High DD was characterizedby prefrontal hypoactivation and appears to result from affective decision-making.