Human auditory steady-state evoked potentials during selective attention.

The human auditory steady-state evoked potentials were examined during several different tasks requiring attention. Both Fourier analysis and signal averaging were used to measure the responses at stimulus rates between 37 and 41/sec. There was no effect of attention on the amplitude and phase of the steady-state evoked potentials when subjects either counted successive increments in stimulus intensity or read a book. In a dichotic listening task, there were clear changes in the late transient evoked potentials with selective attention but no changes in the steady-state responses. Furthermore, the steady-state potentials recorded during reading were not different from those obtained while the subjects were selectively attending to the auditory stimuli in one ear. There is therefore no evidence that the auditory steady-state responses are affected by attention.