Electrophysiological evidence for response priming and conflict regulation in the auditory Simon task.

The Simon effect refers to the finding that responses are faster when the task-irrelevant stimulus and response location correspond than when they do not. The present study examined the role of location-based response priming and its regulation by an ancillary monitoring mechanism (AMM) for the auditory Simon effect, manipulating response modality and analyzing event-related brain potentials (ERPs). An auditory Simon effect was obtained for responses with hand, foot, and eyes. Lateralized ERPs revealed a mix of location-based attentional and motor-related activations early on during information processing. The Simon effect in reaction time (RT) was absent or largely reduced when a non-corresponding rather than a corresponding trial preceded, indicating control over location-based response priming. Importantly, RT modulations as a function of the correspondence sequence were mirrored in the amplitude of a negative difference wave (N2c), in accord with the view that response priming is under control of an AMM. In conclusion, both behavioral and electrophysiological measures revealed effect patterns that are consistent with an information-processing model that assumes asynchronous transmission from two separate processing routes to the motor system and top-down control by an AMM over task-irrelevant response priming.