Intelligence and Personality

Abstract

Chalke and Ertl (1965) were the first to report evoked-potential correlates of intelligence. They compared the latencies of visually-evoked responses, recorded from bipolar leads placed over the left motor area, in three groups of subjects: 33 students with superior IQ’s; 11 subjects with IQ’s in the “low-average” range; and 4 mental retardates with IQ’s ranging from 50 to 65. Three of the five latencies measured (peaks at 142 to 374 msec) yielded significant differences between the groups; the less intelligent subjects had longer latencies. Although their findings are of great interest, they are subject to criticism on several grounds. The retardate group was small. Age was poorly controlled and sex not stated. The averaging technique was somewhat unorthodox, as was lead placement. However, Chalke and Ertl noted that the latency measurements obtained with their technique agreed well with those obtained with a digital averager, and they selected their lead placement with the idea of “maximizing the input—output delay and thus to enhance the possibility of actually measuring central processing time.”