Effects of attention on auditory evoked middle latency potentials.

The effects of attention on the auditory evoked middle latency potentials (MLPs) were examined in 23 normal subjects. Early positive-negative-positive-negative waves (about 8, 11, 15 and 18 msec peak latencies) and a late positive one (about 30 msec peak latency) were recorded from the unilateral mastoid-nose tip. The amplitudes of the early portions of MLPs to binaural 50 dB SL clicks during attention decreased as compared to those obtained when the subjects were not attending to the test stimuli. No significant difference was seen in the latency of any early wave.