Information-Processing Load and Variability of Visual Evoked Potentials

Abstract

5 subjects were assigned two tasks during which they were simultaneously presented brightness-changes of the spot light on the CRT and the speech in a foreign language. They were asked to count the number of the changes in the visual task and listen to the speech to discern the content in the auditory task. A pair of averaged visual evoked potentials (VEP) to the brightness-changes were obtained for each task to calculate a subset correlation as an index of the variance of VEP. The mean correlation coefficient of VEP across the subjects was significantly higher during the visual task than that in the auditory task. This means that VEP was more stable during the visual task. The result suggests that the subset correlation measure might be available to evaluate visual information-processing load.