Eye movements during audiovisual speech perception with dyslexia

Abstract

The current study examined audiovisual (AV) speech perception deficit in dyslexic readers. This would be expected based on previous findings revealing that children and adults with dyslexia show a reduced AV speech perception in noise and that they are less effective in benefitting from visual speech cues. The eye-tracking methods were used for the first time to provide evidence of an AV speech perception deficit in dyslexic readers. Based on the data obtained from normal readers' it was expected that dyslexic readers would make fewer fixation on the mouth and that the total fixation time spent on the mouth would be less compared with normal readers. 12 adult dyslexics (M = 23 years) and 12 matched in age typical readers (M = 23 years) participated in the study. Speech perception was examined with syllable identification task. Stimuli /ba/, /ga/ and /da/ were presented in three different conditions: AV in quiet, AV in white noise and a visual only condition. Eye-tracking data were collected while the participants carried out the experimental task. Dyslexic readers had a deficit in unimodal, namely visual speech perception (p=.039). Eye movements in dyslexic readers during AV speech perception were not different from the normal readers. The results of the current study revealed a specific deficit in the perception of visual speech cues in adult individuals with dyslexia, which can indicate a general deficit in multimodal speech integration and require further research. A discussion of possible limitations in the experimental design is presented in this study and might be helpful in a further eye-tracking research of AV speech perception in dyslexia.