The locus of dual-task interference: Psychological refractory effects on movement-related brain potentials.

Sought to measure the motor potentials for each of 2 concurrent tasks and to use these measurements to identify the locus of dual-task interference. Lateralized readiness potentials (LRPs) were measured in the psychological refractory period paradigm, in which a separate response is required to each of 2 successive signals. As the interval between the signals decreased, the 2 reaction time (RT) tasks increasingly overlapped and the 2nd RT was prolonged. The LRP for the 2nd task was also delayed but maintained a constant temporal relation with the 2nd RT and sometimes preceded the 1st-task RT. The results indicate that (1) independent measures of the LRP can be obtained for each of 2 concurrent tasks, (2) slowing of the 2nd task was caused by a delay in processes that precede LRP onset, and (3) the 1st task may cease to interfere with the 2nd considerably before producing an overt response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)