research showing that the ACC uses all types of reinforcement information – rewards as well as errors – to build up a sense of action value, it is not clear how this region assigns importance to individual pieces of information. Intuitively, reward information is likely to be more valuable in a reward-sparse environment, and it may be that the ACC plays an important role in learning the average reward rate for the available options (see also Amiez, Joseph and Procyk, 2006). Similarly, the significance of information will also be affected by how changeable the local conditions are, which may also be encoded in the ACC.
