Event-Related Potential Study of P2 and N2 Components on Fast and Slow Responses in the Auditory Condensation Task

In tasks involving response choice based on certain stimulus-to-response mappings, at least two stages of information processing may be involved: (1) formation of sensory stimulus object representations leading to stimulus identification, and (2) application of stimulus-to-response mappings (i.e. “task rules”) to these representations leading to response selection. Most of the research done in this area involved simple reflex-like stimulus-to-response mappings, thus addressing mostly the perceptual aspect of decision making. Here we used the condensation task, which involves more complex stimulus-to-response mappings. Within each subject, we divided participants’ responses into four conditions depending upon performance speed and accuracy: fast correct, fast erroneous, slow correct and slow erroneous responses. We compared event-related potentials between these conditions. We found that P2 amplitude was related to performance accuracy, the effect being evident for fast but not for slow responses. N2 amplitude was increased for slow responses – both correct and erroneous. We suggest that fast errors result mostly from erroneous sensory representations that immediately become translated into actions in conditions of low motor threshold. On the contrary, slow responses happen in conditions of low executive attention, through reevaluation of sensory representations and invocation of cognitive control process via the mechanisms of response conflict detection.