Paying out one versus paying out all trials and the decrease in behavioral and brain activity in the Balloon Analogue Risk Task.

Both pay out for all the trials (pay-all) and pay out for only one randomly selected trial (pay-one), are widely used in economics experiments to elicit choices from study participants. However, whether pay-all and pay-one payments modulate risk-taking and decision-making in the same manner remains controversial. In the present study, we used event-related potentials (ERPs) with the Balloon Analogue Risk Task (BART) to investigate the effects of the pay-all and pay-one payments on dynamic sequential decision-making behavior under uncertainty and brain activity. Behavioral data showed an increased uncertainty aversion, especially after negative feedback (balloon explosion) during the BART in the pay-all condition, as compared to those in the pay-one condition. The ERP data demonstrated a larger feedback-related negativity (FRN) in response to the balloons that exploded during decision-making in the pay-all condition, as compared to those in the pay-one condition. In addition, in the pay-all condition, the FRN amplitude elicited by the explosion of the balloon correlated with the future decision-making behavior, although this correlation was not observed in the pay-one condition. In contrast, the P300 component was unresponsive to payment method manipulation. These findings demonstrate the differential effects of the pay-all versus the pay-one payments on decision-making behavior under uncertainty and brain activity, suggesting that the payment method plays an important role in dynamic decision-making studies.