N2ac: An ERP component associated with the focusing of attention within an auditory scene


  • This study was made possible by grant R01MH076226 from the National Institute of Mental Health to S. J. L. Preparation of the manuscript was supported by a National Science Foundation graduate research fellowship to M. L. G.

Address correspondence to: Marissa Gamble, Duke University, Box 90999, Durham, NC 27708, USA. E-mail: marissa.gamble@duke.edu


Humans must often focus attention onto relevant sensory signals in the presence of simultaneous irrelevant signals. This type of attention has been explored in vision with the N2pc component, and the present study sought to find an analogous auditory effect. In Experiment 1, two 750-ms sounds were presented simultaneously, one from each of two lateral speakers. On each trial, participants indicated whether one of the two sounds was a pre-defined target. We found that targets elicited an N2ac component: a negativity in the N2 latency range at anterior contralateral electrodes. We also observed a later and more posterior contralateral positivity. Experiment 2 replicated these effects and demonstrated that they arose from competition between attended and unattended tones rather than reflecting lateralized effects of attention for individual tones. The N2ac component may provide a useful tool for studying selective attention within auditory scenes.