The effects of response sharing and stimulus presentation frequency on event-related potentials in an auditory...

An experimental model for investigating the processes involved in reacting to unpredictable events is the oddball paradigm. We investigated how the commonality or independence of response options (i.e., many-to-one vs. one-to-one stimulus-response mappings) influences processing in an auditory oddball paradigm. Participants performed a discrimination task with two one-to-one and one two-to-one mappings. The pattern of conflict- and oddball-related N2 event-related potentials suggest that information that would allow correct responding is represented at the latency of the N2. Integration of this information takes place only by the latency of P3b, and longer reaction times to rare stimuli are probably due to processes preventing the utilization of this information. We also suggest that, in the given task context, conflict-related N2 may reflect the number of alternative stimuli leading to alternative response options.