Are Atypical Face Processing and Reduced Joint Attention Characteristics of the Broader Autism Phenotype?

Background: Autism is often characterized by atypical face processing including reduced attention to eyes and increased attention to mouths (Klin et al., 2002; Jones et al., 2008), and decreased joint attention (e.g. Sigman & Ruskin, 1999).  Decreased attention to eyes was concurrently associated with more autistic symptomatology (Jones et al., 2008; but see Klin et al., 2002) but may not predict later diagnostic outcomes for infant siblings of children with autism (Young et al., 2009). Additionally, increased attention to mouths was associated with decreased social symptoms among adults with autism (Klin et al., 2002). Reduced joint attention is longitudinally associated with increased symptoms of autism (Gillespie-Lynch et al., 2012). Given that atypicalities of face processing and joint attention distinguish between individuals with and without autism and may be associated with autistic symptomatology, they could be characteristics of the broader autism phenotype (BAP).  Both individuals with autism and their non-autistic siblings looked less at eyes than controls (Dalton et al., 2006). However, reduced joint attention may be specific to siblings who are themselves diagnosed with autism (Rozga et al., 2011).

Objectives: This eye-tracking study investigates whether atypical face processing and reduced joint attention are characteristics of the BAP by determining if they a) distinguish between children with and without autism and b) are associated with symptoms of autism among non-autistic siblings of children with autism.

Methods: Participants included 20 children with and without autism matched by chronological age (mean age 56 months) and eighteen 36 month-old siblings of children with autism who did not meet criteria for autism. Participants were shown a video of a smiling model while their eye movements were tracked with a Tobii 1750 eye-tracker. After each participant fixated on an attention getter, the model looked toward the participant, turned to the left or right toward one of two identical objects, labeled it, and looked at it. The model’s direction of gaze was counterbalanced across 8 trials. Symptoms of autism were assessed with the ADOS.

Results: Children with autism exhibited less joint attention (t (38) = 3.022, p = .005) and less attention to eyes (U (38) = 125.5, Z= -2.015, p = .044) than children without autism. No group differences in attention to the mouth were observed (p = .570).  No associations between face processing or joint attention and symptoms of autism were observed among non-autistic siblings of children with autism (p > .05). Interestingly, attention to the mouth (rs (16) = .492, p = .038) but not the eyes (p = .265) was associated with joint attention among siblings at 3 years of age. No such association was observed for children with or without autism at a mean age of 4.5.

Conclusions: Children with autism exhibited less joint attention and less attention to eyes than typically developing children. However, no associations between gaze patterns and autistic symptomatology were observed among non-autistic siblings of children with autism. This study does not provide evidence that atypical joint attention or atypical face processing are characteristics of the BAP.