音声言語知覚における視線の影響

The effects of gaze movement on audiovisual speech perception

　話し言葉の理解では，音声だけでなく話者の顔の視覚情報も利用されており，視線計測はその実際に取得された情報を知るうえで有用である．本研究では音声言語知覚における視線の影響を検討するため，マガーク効果に着目し，2つの実験を行った．日本語を母語とする健常者を対象として，実験1ではマガーク効果における視線を計測した．その結果，マガーク効果が生起するときは様々な顔の部位を注視して視線の移動距離が長く，マガーク効果が生起しないときは口を限定的に注視して視線の移動距離が短かった．これを受けて，実験2では視線統制によるマガーク効果の変化を検討した．結果として，マガーク効果の生起率は注視部位や視線の移動距離の影響を受けた．以上のことから，マガーク効果と視線の関連性が示された．マガーク効果は視覚情報の利用度に応じて変化する．視線誘導による視覚情報を活用して音声言語知覚の向上が期待される．

　In speech perception, the visual information about a talker's face is known to influence the perception of the auditory information.　Eye tracking is a useful method in studying visual information involved in speech perception.　In this study, we performed two experiments with a focus placed on the McGurk effect to examine the effects of gaze movement to audiovisual speech perception.　In Experiment 1, we measured the distance of eye gaze movement and looked at how it relates to the McGurk effect in healthy subjects whose mother tongue was Japanese.　When the distance of gaze movement was long and subjects watched various parts of the face, the McGurk effect was confirmed.　However, when the distance was short and the subjects only watched the speaker's mouth, no McGurk effect was confirmed.　As a result of these findings, we performed Experiment 2 to examine changes in the McGurk effect by controlling eye gaze.　It was found that the McGurk effect was affected by the gaze fixation position and the distance of the gaze movement.　These findings suggest that there is some relationship between the McGurk effect and eye gaze.　The McGurk effect changes depending on the usage of visual information.　It is expected that audiovisual speech perception would be improved by effective use of visual information based on the gaze guidance.