We hypothesized that during binary economic choice, decision makers use the first option they attend as a default to which they compare the second. To test this idea, we recorded activity of neurons in the dorsal anterior cingulate cortex (dACC) of macaques choosing between gambles presented asynchronously. We find that ensemble encoding of the value of the first offer includes both choice-dependent and choice-independent aspects, as if reflecting a partial decision. That is, its responses are neither entirely pre- nor post-decisional. In contrast, coding of the value of the second offer is entirely decision dependent (i.e., post-decisional). This result holds even when offer-value encodings are compared within the same time period. Additionally, we see no evidence for 2 pools of neurons linked to the 2 offers; instead, all comparison appears to occur within a single functionally homogenous pool of task-selective neurons. These observations suggest that economic choices reflect a context-dependent evaluation of attended options. Moreover, they raise the possibility that value representations reflect, to some extent, a tentative commitment to a choice.
Bibliographical noteFunding Information:
National Science Foundation (grant number BCS1253576). Received by B. Y. H. National Institutes of Health (grant number DA038615). Received by B. Y. H. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We thank Meghan Castagno, Marc Mancarella, and Caleb Strait for assistance with data collection and Frank Mollica, Steve Piantadosi, and Seng Bum Michael Yoo for valuable discussions.
© 2017 Azab, Hayden.