The anterior cingulate cortex (ACC) has been associated with conditions precipitating an increase in effortful processing or increased attention, including the presence of conflicting information and the detection of errors. The error-related negativity (ERN), an electrocortical response, has been used as a marker for these conditions. The ERN amplitude however is subject to developmental change across the lifespan as well as being sensitive to individual differences in personality, affect, and autonomic responsivity. In this review, we examine the implications of such influences for a standard ACC model of conflict processing, and outline the need of any model of ACC function to include mechanisms that allow for the integration of neurovisceral and cognitive domains.