The Effect of Amblyopia on Visual-Auditory Speech Perception

Abstract

IMPORTANCE Children with a history of amblyopia, even if resolved, exhibit impaired visual-auditory integration and perceive speech differently. OBJECTIVE To determine whether a history of amblyopia is associated with abnormal visual-auditory speech integration. DESIGN, SETTING, AND PARTICIPANTS Retrospective observational study at an academic pediatric ophthalmologic clinic with an average of 4 years of follow-up. Participants were at least 3 years of age and without any history of neurologic or hearing disorders. Of 39 children originally in our study, 6 refused to participate. The remaining 33 participants completed the study. Twenty-four participants (mean [SD] age, 7.0 [1.5] years) had a history of amblyopia in 1 eye, with a visual acuity of at least 20/20 in the nonamblyopic eye. Nine controls (mean [SD] age, 8.0 [3.4] years) were recruited from referrals for visually insignificant etiologies or through preschool-screening eye examinations; all had 20/20 in both eyes. EXPOSURES Participants were presented with a video demonstrating the McGurk effect (ie, a stimulus presenting an audio track playing the sound /pa/ and a separate video track of a person articulating /ka/). Normal visual-auditory integration produces the perception of hearing a fusion sound /ta/. Participants were asked to report which sound was perceived, /ka/, /pa/, or /ta/. MAIN OUTCOME AND MEASURE Prevalence of perception of the fusion /ta/ sound. Prior to the study, amblyopic children were hypothesized to less frequently perceive /ta/. RESULTS The McGurk effect was perceived by 11 of the 24 participants with amblyopia (45.8%) and all 9 controls (100%) (adjusted odds ratio, 22.3 [95% CI, 1.2-426.0]; P = .005). The McGurk effect was perceived by 100% of participants with amblyopia that was resolved by 5 years of age and by 100% of participants whose onset at amblyopia developed at or after 5 years of age. However, only 18.8% of participants with amblyopia that was unresolved by 5 years of age (n = 16) perceived the McGurk effect (adjusted odds ratio, 27.0 [95% CI, 1.1-654.0]; P = .02). CONCLUSIONS AND RELEVANCE This pilot study suggests that children with a history of amblyopia have impaired visual-auditory speech perception. Early childhood appears to serve as an approximate time point for the development of successful visual-auditory fusion, by which time amblyopia must have either resolved or begun. Interventions to resolve amblyopia may not only influence visual acuity but may also influence the perception of sound.

Alterations in audiovisual simultaneity perception in amblyopia

“…The broadening of the simultaneity window among participants with amblyopia was similar among amblyopic eye only, fellow eye only, and binocular viewing conditions, suggesting that these perceptual differences may involve an abnormal central multisensory network for temporal processing. The results are similar to those reported for adults with early monocular deprivation from congenital cataract,[69] and demonstrate that the abnormalities in audiovisual integration in the most prevalent forms of amblyopia are not specific to the McGurk effect (i.e., AV speech perception)[22–24], but generalize to simultaneity judgements of simple, non-speech stimuli.…”

“…[51, 53] Indeed, if a decisional bias toward unity was the cause of a widened simultaneity window in amblyopia, one might also expect that susceptibility to the McGurk effect would also be heightened, but this is not the case. [22, 23]…”

“…As with decisional bias toward unity, however, the heightened McGurk effect expected from enhanced AV perceptual binding has not been observed in amblyopia. [22–24] Rather, the accompaniment of a wide simultaneity window in amblyopia with low susceptibility to the McGurk is akin to the relation observed in visually normal individuals,[57] and suggests an impairment in the ability to resolve asynchronous AV pairs as unique events. A possible mechanism for such an impairment is temporal uncertainty in the visual domain.…”

“…[19–21] Beyond the purely visual domain, recent work has shown that amblyopia also affects multisensory integration in speech perception, manifest as reduced susceptibility to the McGurk effect, even while viewing with both eyes. [22–24]…”

Similar frequency of the McGurk effect in large samples of native Mandarin Chinese and American English speakers

“…Reduced visual abilities such as those found in amblyopia are linked to reduced frequency of the McGurk effect in children (Burgmeier et al, 2015) and adults (Narinesingh, Wan, Goltz, Chandrakumar, & Wong, 2014). Even in healthy subjects, responses to the McGurk effect may depend on task instructions.…”