What is and what could have been: an ERP study on counterfactual comparisons.

Prior research indicates that the feedback-related negativity (FRN) reflects a good versus bad evaluation of decision outcomes, which is insensitive to the local utilitarian relation between chosen and unchosen outcomes. We tested whether this negative finding holds when the chosen outcome has an objective value of zero and therefore a comparison with the unchosen outcome is needed to identify overall choice valence. Participants completed a gambling task in which chosen and unchosen options could result in monetary wins, losses, or breaking even. Results show that the FRN does not reflect local favorableness but rather a dichotomy of gain versus no-gain for both chosen and unchosen outcomes. In contrast, P300 amplitude appears to reflect motivational salience derived from counterfactual comparisons of chosen and unchosen outcomes. Based on our and prior findings, we propose a threefold taxonomy of contextual factors and their relation to the FRN.