Todd S. Braver, Deanna M. Barch, Jeremy R. Gray, Anterior Cingulate Cortex and Response 1 2 David L. Molfese and Avraham Snyder Conflict: Effects of Frequency, Inhibition Department of Psychology, Washington University, and Errors Department of Cognitive Science, University of California, San Diego and Department of Radiology, Washington University information processing. By conf lict, we mean interference or Anterior cingulate cortex (ACC) may play a key role in cognitive interactions between di fferent information processing path- control by monitoring for the occurrence of response conflict (i.e. ways. In a series of computer simulation studies, we provide a simultaneous activation of incompatible response tendencies). Low-frequency responding might provide a minimal condition for detailed examination the theoretical consequences of this eliciting such conflict, as a result of the need to overcome a hypothesis (Botvinick et al., 2001). One of the predictions that prepotent response tendency. We predicted that ACC would be arises from such a theoretical exploration is that the ACC should selectively engaged during low-frequency responding, irrespective be engaged whenever two or more incompatible responses of the specific task situation. To test this hypothesis, we examined are simultaneously activated. A number of recent neuroimaging ACC activity during the performance of simple choice-discrimination studies have provided direct empirical support for this predic- tasks, using rapid event-related functional magnetic resonance tion (Botvinick et al., 1999; Barch et al., 2000, 2001; Carter et al., imaging. Subjects were scanned while performing three tasks 2000; Casey et al., 2000; MacDonald et al., 2000). thought to tap...