Preferential Attention to Audiovisual Synchrony Predicts Language Ability in Toddlers with ASD

Background: Children with ASD exhibit atypical patterns of visual attention to the social world, responding differently to physical and social contingencies relative to non-autistic peers. In studies examining preferential attention to audiovisual synchrony, we showed that ASD infants are relatively insensitive to social contingencies afforded by talking faces, focusing instead on physical contingencies between light and sound. By manipulating audiovisual stimuli comprising faces and shapes synchronized with speech and tones, we found that TD controls exhibited a preference for synchronous faces and speech, lacking in ASD participants, even though groups did not differ in baseline sensitivity to audiovisual synchrony. In early studies, significant differences were found based on simple measures of visual attention derived from mean relative fixation durations. More recently, we applied techniques from information theory to quantify differences between full probability distributions of eye-tracking trajectories across groups, and derived optimal classifiers based on a generalized likelihood ratio test that achieved sensitivity 79.5% and specificity 97.4% in discriminating ASD infants from TD controls. In evaluating our classifier performance, we noticed that ASD infants with eye-tracking likelihood-ratio scores closer to the typical range appeared to have better language ability, suggesting a potential relationship between sensitivity to audiovisual synchrony and the emergence of spoken language.

Objectives: Our goal was to test whether information-theoretic measures of differences in visual attention to audiovisual synchrony that discriminate between TD and ASD toddlers predict language ability in those children.

Methods: Toddlers with autism (N=34) and typically developing controls (N=20) participated in a simple preferential-looking paradigm based on split-screen presentation of video stimuli (faces and shapes) paired with audio stimuli (speech and tones). Using different combinations of video and audio stimuli, and manipulating audiovisual synchrony between the two, we tested for differences in attention to social and physical contingencies. Eye tracking was used to quantify response. Using machine-learning techniques, we derived optimal measures of overall attention and attention to social target across all stimulus combinations, focusing on responses to speech and non-speech. An optimal classifier was derived using a generalized likelihood ratio test calculated from the entire joint distribution of our measures across groups. Receiver operating characteristics were further used to quantify classification performance, using leave-one-out cross-validation with the log likelihood ratio as the test statistic. To determine the relationship between preferential attention to audiovisual synchrony and language ability, we calculated the correlation between the log likelihood ratio scores and the receptive and expressive language scores determined from clinical assessments using the Mullen Scales of Early Learning.

Results: We found significant correlations (P<0.05) between the log likelihood ratio scores (speech/non-speech conditions) and both receptive (r=-0.332/-0.394) and expressive (r=-0.413/-0.409) language scores.

Conclusions: Patterns of preferential attention to audiovisual synchrony that discriminate between ASD and TD children are also predictive of language ability in those children, suggesting that differential sensitivity to social and physical contingencies in talking faces is a pathway to spoken language in autism.