Abstract

KONDO, Aki  and  WATANABE, Katsumi. Inter-trial effect in luminance processing revealed by magnetoencephalography. Univ. Psychol. [online]. 2013, vol.12, n.spe5, pp.1563-1569. ISSN 1657-9267.

In this study, we examined whether luminance processing in the human visual system would exhibit any history effect (i.e., inter-trial modulation) in psychophysical and magnetoencephalographic experiments. A disk was presented against a black background at various luminance levels in a randomized order. During the MEG recording, participants were instructed to rate the brightness of the disk (magnitude estimation) and to report it aloud during inter-stimulus interval. The MEG results showed that the neuromagnetic activation around 200-220 ms after the stimulus onset in the left occipito-temporal regions at a given trial was weaker when the disk luminance in the immediately prior trial was higher. An inverse inter-trial effect was also observed in the psychophysical experiment. These findings suggest that the neuromagnetic activity reflects the inter-trial modulation of luminance processing that correlates with the subjective perception of brightness.

Keywords : luminance; inter-trial effect; magnetoencephalography (MEG); Perception; occipito-temporal region; Cognitive Science.

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