Some effects of 'mental set' on the electrophysiological processes of the human cerebral cortex.

Abstract

A series of expts. were performed to investigate the effects of a "set" to respond manually to a light upon the latent time of blocking of the alpha rhythm of the cortex to that light. There was found to be a reduction in the mean latent time of blocking, the reduction being greater in the case of a "set" to respond with speed rather than with discrimination. Variability was reduced equally in the 2 conditions, discrimination and speed. One or both of 2 factors were assumed to be responsible for the observed phenomena peripheral (proprioceptive) stimulation, or central reorganization. Proprioceptive stimulation was experimentally induced by having the subjects support weights; central reorganization was induced by having the subjects make covert, rather than overt responses, to the light. The reduction in mean latent time of blocking was evidently the end result of increased peripheral stimulation which results from increased muscle tension during any "set." The decrease in variability was concluded to be the result of central reorganization acting with increased peripheral stimulation.