EXPERIMENTS ON 'THE CORTICAL CORRELATE OF PATTERN VISION,'
RAND CORP SANTA MONICA CALIF
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The Kohler-Held experiment on DC potential shifts related to visual stimulation was repeated, using two channels of DC recording. In a preliminary experiment, 11 subjects were given 638 exposures to a moving bar of light. Twentythree per cent of the trials were successful, i.e., a DC response from an occipital electrode referred to a vertex electrode was observed. When records of 8 of the 11 subjects were scored during nonstimulus periods, 31 successes were observed. It is concluded that the DC responses are not necessarily related to the occurrence of the visual stimulus. A second experiment was conducted on 10 subjects with two channels of DC recording. These results suggest that the source of the DC changes may be the corneo-retinal potential from eye movement or other areas of the brain rather than the occipital areas. It is concluded that the Kohler-Held phenomenon, although it may be recorded from all subjects, is statistically infrequent and the conditions under which it does appear are rather obscure. It is suggested that the name, The Cortical Correlate of Pattern Vision, is premature. Author