Perception of auditory-visual simultaneity changes by ambient illumination
* Presenting author
In this study, we investigated changes in the point of subjective simultaneity (PSS) between auditory and visual stimuli by changes in ambient illumination. The test stimuli were a pure tone sound of 1000 Hz at 80 dB SPL and white light of LED at 21.9 cd/m². The illuminance levels at around the light source and at the subject’s eyes were adjusted at the following 4 conditions;(100 lx, 100 lx), (100 lx, 1000 lx), (1000 lx, 100 lx), and (1000 lx, 1000 lx). Nine people in their early 20s participated in the experiments. Synchronized sound-light stimuli, which were the same as the test stimuli, were presented as the preceding stimuli, followed by the test stimuli at an interval 1000 ms. The test stimuli had a stimulus onset asynchrony (SOA) of 0, ±20, ±40, ±80, or ±160 ms. After each presentation of the test stimuli, we asked subjects to answer which of the stimuli — sound or light — they perceived first. Then we evaluated the PSS of the test stimuli and considered the influence of ambient illuminance on the PSS. As a result, the PSS shifted toward positive direction. We showed that the PSS shift depended by changes in ambient illumination.