ERPs and RTs during performance of concurrent tasks of increasing difficulties

Sixteen right-handed healthy volunteers conducted a primary visuomotor task (playing with a video-game) while performing a secondary task of sensory discrimination (e.g., auditory oddball), in which event-related potentials (ERPs) and reaction times (RTs) were recorded. As the experiment design assessed the effects of manipulating primary-task difficulty on ERP components (Nl, P2, N2, P3) and RT values, different levels of difficulty were provided: leve1 0 included only the secondary (oddball) task; levels 1, 2 and 3 required the dual-task performance, with increasing difficulties of the primary task. The introduction of the primary visuomotor task increased the latencies of RT and ERP P3 component, and decreased Nl and P3 amplitudes. Increasing the difficulty of the primary task did not modify RT and ERP latencies further, but induced a systematic decrease in P3 amplitude.