2014 Volume 32 Issue 1 Pages 11-17
Figures with illusory contours (IC) elicit a specific electrophysiological response in comparison with control figures at around 90–200 ms after stimulus onset. Although such IC effects have been considered to reflect automatic perceptual processing of IC in visual cortical areas, examinations are not sufficient. The present study examined effects of cognitive task load on the IC effect in event-related potentials (ERPs). ERPs were recorded from 17 participants who were presented with random sequences of IC and control figures, and digits while engaged in counting of digits (low-load task) and calculations (high-load task). As a result, only in the low-load condition, more negative ERPs in response to the IC figure were observed during 110–160 ms over right occipital-temporal electrode sites. The result suggests that cognitive load associated with calculations affected IC processing, thus the perceptual processing of IC may not be fully automatic.
