Variations in early and late event-related components of the auditory evoked potential with task difficulty.

A variation in the difficulty of an auditory discrimination was used to investigate the relationship between the event-related P165, N2 and P3 components of the auditory evoked potential. Equivalent increases in the latencies of all 3 components were found with increased task difficulty. The P165 component, however, could be differentiated from the two later components since it increased in amplitude with increased task demands while the N2 and P3 amplitudes remained constant. It is suggested that the P165, N2 and P3 components comprise a functional sequence in the processing of rare events and possibly involved in a subject's preparations for the future.