Infant Attention to Eyes Versus Mouth Varies With Mouth Movement Speed, Family History of Autism and Language Development

PURPOSE: Patterns of visual attention to faces are mixed in infants with a family history of autism relative to controls. Attention deficit hyperactivity disorder (ADHD) often co-occurs with autism and could represent one source of variance in findings. Heterogeneity in language skills may represent another source of variance. We investigated longitudinal patterns of attention to eyes and mouths in infants with and without an elevated familial likelihood (EL) of autism and/or ADHD, and examined associations with language development. METHODS: The sample included 160 infants (EL-autism = 79, EL-ADHD = 31, EL-autism+ADHD = 21, Typical Likelihood (TL) of autism and/or ADHD = 29). We measured eye-to-mouth looking ratios of 5, 10 and 14 month olds who viewed pairs of faces with mouths moving at low (1 Hz), medium (6 Hz) and high (10 Hz/15 Hz) temporal frequency. Language skills were measured throughout infancy and at 36 months. RESULTS: Eye looking (relative to mouth) decreased as a function of age and was reduced for speech-like frequencies (6 Hz) compared to slower frequencies. Infants with EL-autism looked more to the eyes than TL infants, but this effect was attenuated in the presence of familial ADHD. Controlling for 14 months word acquisition, higher receptive language at 36 months was associated with greater eye looking. CONCLUSION: Our findings confirm age-related changes in eye-to-mouth looking across development and suggest that variability in familial ADHD and heterogeneity in language skills influence attentional differences in infants with a family history of autism. Future family history studies should investigate this heterogeneity using neurophysiological methods.