We analyzed foraging signal time courses in a region centered on the overlap between foraging search value and decision value difference effects (Fig. 2, C and D). The blood-oxygen-level–dependent (BOLD) contrast for ACC was positively correlated with the value of searching the environment and negatively correlated with the value of engaging with the current encounter option, regardless of the choice participants ultimately made (Fig. 2, E and F). The frame of reference in which values are encoded in ACC is thus fixed in relation to response strategy, that is, searching or engaging. This contrasts with vmPFC and other regions where value is encoded in a flexible reference frame tied to the choice taken or attended (9, 10). Comparing search value signals in ACC, we found a more rapid increase (greater slope) on search than engage choices [t(17) = –2.54, P = 0.021] consistent with earlier, stronger signals in search decisions (fig. S8) and faster accumulation of search evidence in ACC on search choices (4). In search choices, there was also an effect of search cost (Fig.2F).