Cortical potentials evoked by a TV pattern reversal stimulus with varying check sizes and stimulus field.

With the use of television equipment the influence of check size and stimulus field on the pattern evoked cortical potentials was investigated. Maximum responses were found with 20' and 40' checks. The major part of the responses was initiated from a ring between 1.25 degrees and 2.5 degrees eccentricity, though relatively per stimulus area the response became progressively larger the smaller the stimulus field.