Middle latency components of the auditory evoked response: lateral differences and changes by mental tasks

Middle latency components in response to stimulation of both ears with 50 dB SL clicks at a rate of 10/sec were recorded in young healthy subjects from the left mastoid-nose tip and right mastoid-nose tip. All were right-handed. 1) Lateral differences were found in most subjects. As to the largest peak-to-peak amplitude, the amplitude on the right side was larger than that on the left in 18 subjects, but the reverse was found in 11. Only two showed little differences. 2) The amplitudes on the right side during addition were larger than those when merely looking at numerals. The amplitudes during multiplication were larger than those during addition.