Nat. Neurosci. 7, 1370–1375 (2004)

A reference was deleted from this paper during the production process. It should have read as follows:

17. Botvinick, M., Nystrom, L.E., Fissell, K., Carter, C.S. & Cohen, J.D. Conflict monitoring versus selection-for-action in anterior cingulate cortex. Nature 402, 179–181 (1999).

In addition, through a typographical error, a quotation mark was omitted from the last sentence of the legend for Table 1. The correct version should read: Cumulative total from the “Reduced reward only” and the “Both reduced reward & double arrow” categories represents all cells with significant response to reduced-reward trials.