The effect of luminance on the saccadic response induced by auditory and visual stimuli and the developmental changes in the effect
Poster Presentation

Masaharu Kato
Tokyo Women's Medical University

Mizue Matsumoto
Yokohama National University

Hifumi Tsubokura
Tokyo Women's Medical University

Yukuo Konishi
Tokyo Women's Medical University

     Abstract ID Number: 86
     Full text: Not available
     Last modified: March 21, 2005

Abstract
The saccadic response time (SRT) decreases more in response to spatially congruent auditory visual stimuli than to visual or auditory stimuli only. Moreover, the SRT increases in response to spatially incongruent auditory visual stimuli more than to visual or auditory stimuli only. These facilitatory and inhibitory effects are regarded as the consequence of auditory and visual spatial integration in the brain. Here, we investigated the influence of luminance on these effects in human adults and infants. In adults, we found that the change in the SRT with spatial disparity of the auditory visual stimuli was modified by the luminance of the visual stimuli. For infants aged between 4 and 10 months, stronger luminance in the incongruent condition delayed the saccade in all age groups, while weaker luminance delayed the saccade only in 8- and 10-month-old infants. In the congruent condition, no facilitatory effect was observed in any age group. These results suggest that there is an optimal luminance level that maximizes these effects in adults, and that the maturation involved in the process of the saccade in response to an auditory visual stimuli has two steps: the inhibitory process of the saccade matures first, and the facilitatory process comes later.