Photic stimulation, selective attention, and averaged evoked responses in humans

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Lenin Eduardo Salmon (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
M. Russell Harter

Abstract: The present study was an attempt to investigate the differential effects of attention upon visually evoked cortical responses (VERs) when preparatory states and peripheral influences are reduced to a minimum. Four subjects were presented a random series of relevant and irrelevant light flashes and were instructed to count the number of relevant signals (count condition) or to make a key release every time the attended stimulus was presented (reaction time condition). Stimuli were presented at a constant rate of 520 msec. (fast rate), or 1030 msec. (slow rate). Subjects were instructed to fixate a central reference point on the projection screen throughout the length of the trial. Similarly, they were asked to withhold any response not related to the task. Averaged VERs from the occipital cortical region showed a consistent increase in amplitude at latencies of 220-250 msec. and 290-340 msec. when the stimulus was relevant, as compared to VERs to the same stimulus when it was irrelevant. It was also found that neither response conditions nor rate of presentation had a significant effect on the cortical response.

Additional Information

Language: English
Date: 1971
Visual evoked response
Selectivity (Psychology)

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