No Money, No Problem: Enhanced Reward Positivity in the Absence of Monetary Reward

Abstract

The reward-related positivity (RewP) is an event-related potential (ERP) with a positive amplitude occurring approximately 250-350 ms post-feedback at frontocentral electroencephalogram (EEG) electrode sites. The RewP is typically elicited in monetary gambling tasks and has a relatively larger amplitude for positive vs. negative outcomes. However, the extent to which RewP amplitude is modulated by non-monetary feedback is less clear. To address this issue, EEG was used to record reward-related electrocortical activity during a simple non-monetary gambling task. We hypothesized that the RewP would be enhanced for non-monetary wins relative to losses, which was supported by the results. In our supplementary material, we provide additional analyses suggesting that this effect was not observed for the P3. In sum, RewP amplitudes were larger for positive (nonmonetary) feedback relative to negative feedback at frontocentral electrode sites-suggesting that monetary reward is not necessary to elicit the RewP.

Keywords: EEG; feedback error-related negativity; feedback negativity; medial frontal negativity; monetary; reward positivity.

Figure 1

Participants were told to make a choice in door, and that one door contained a gain in points (win) and the other contained a decrease in points (loss). After a choice, predetermined feedback was given (120 wins and 120 losses).

Figure 2

(Left) Reward-related positivity (RewP) was maximally elicited at frontocentral electrode cites FCz and Cz. Amplitudes for wins (red) were larger than losses (black). (Right) A map of electrocortical polarity at 250–300 ms after presentation of either win or loss feedback. Areas in red reflect maximal positive amplitudes.