Perception of auditory-visual simultaneity changes by ambient illumination

摘要

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/m~2. 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 20's 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.