instruct actions in a conditional learning paradigm; instead, to a foraging animal, a single negative outcome is a piece of evidence that the chosen response may no longer be the best course of action, a fact that is weighed against the recent history of reinforcement. However, as evidence over subsequent trials accumulates that the alternative response does lead to reward, so the likelihood of changing to the new movement increases (EC+1, EC+2, and so on, moving left to right in Figure 7a). By contrast, while monkeys with ACCs lesions are just as likely to change their behaviour as control animals on the first trial after an imposed switch, they are subsequently unable to sustain the correct response, choosing the unrewarded action significantly more often than controls even after receiving as many as eight rewards in succession (Figure 7b). This suggests that rather than the ACCs-group's deficit being one of detecting that a response has been erroneous when not receiving reinforcement, it could instead be better characterised as a failure to integrate reinforcement history over time to work out which response it is desirable to make.
