Common neural choice signals emerge artifactually amidst multiple distinct value signals

Abstract

AbstractA large body of work has identified characteristic neural signatures of value-based decision-making. A core circuit has been shown to track the values of options under consideration, and the dynamics of neural activity associated with this circuit have been found to closely resemble the ramping evidence accumulation process believed to underpin goal-directed choice, most notably in the centroparietal positivity (CPP). However, recent neuroimaging studies suggest that value-based choices trigger multiple value-related neural signatures, some of which are unrelated to decision-making per se but instead reflect reflexive affective reactions to one’s options. Here, we use the temporal resolution of EEG to test whether choice-independent value signals could be dissociated from well-known temporal signatures of the choice process. We show that EEG activity during value-based choice can be decomposed into distinct spatiotemporal clusters, one stimulus-locked (associated with the affective salience of a choice set) and one response-locked (associated with the difficulty of selecting the best option). We show thatneitherof these clusters meet the criteria for an evidence accumulation signal. Instead, and to our surprise, we find across two studies that stimulus-locked activity canmimican evidence accumulation process when aligned to the response (as with the CPP). We then re-analyze two previous studies that demonstrate an evidence accumulation signal in the CPP – one during value-based decision-making, the other during perceptual decision-making – and show that this signal disappears when stimulus-locked and response-locked signals are jointly accounted for. Collectively, our findings show that neural signatures of value can reflect choice-independent processes that when analyzed using standard approaches, can look deceptively like evidence accumulation.Significance StatementTo choose, people must evaluate their options and select between them. Selection is well described by a process of accumulating evidence up to some threshold, with an electrophysiological signature in the centroparietal positivity (CPP). However, decision-making also gives rise to value signals reflecting affective reactions and other selection-unrelated processes. Measuring EEG while participants made value-based choices, we identified two spatiotemporally distinct value signals, neither reflecting evidence accumulation. Instead, we show that evidence accumulation signals found in the CPP can arise artifactually from overlapping stimulus- and response-related activity. These findings call for a significant reexamination of established links between neural and computational mechanisms of choice, while inviting deeper consideration of the array of cognitive and affective processes that occur in parallel.