Previous investigations using eye-tracking methods have reported reduced fixation to salient social cues such as eyes when participants with autistic spectrum disorders view social scenes. However, these studies have sampled relatively able participants with good language skills.
To explore visual fixation patterns to dynamic social stimuli in different language phenotypes within the autism spectrum.
The eye-movements of twenty-eight teenagers with autistic spectrum disorders and 18 typically developing peers were recorded as they watched videos of same-aged peers interacting in familiar situations and environments. Within the autistic spectrum, we contrasted the viewing patterns of those with language impairments and those with age-appropriate language. The proportion of time spent viewing eyes, mouths and other aspects of the scenes was calculated across video clips. In addition, the percentage of viewers in each group showing a significant preference for viewing eye regions of the face was calculated. Finally, the association between viewing patterns and social/communicative competence was measured.
Individuals with autistic spectrum disorders and age-appropriate language abilities spent significantly less time looking at the eyes than typically developing peers. In contrast, there were no differences in viewing patterns between those with language impairments and typically-developing peers. The relationship between language ability and fixating eyes and mouths was different in the two clinical groups. A positive association between eye fixation and vocabulary knowledge was evident for those with language impairment, but the opposite pattern was seen in the more linguistically able group.
We propose that attention to both the eyes and mouth is crucially important for language development and communicative competence. Small differences in fixation time to eyes may not be sufficient to disrupt social competence in daily interactions. A multiple cognitive deficit model of autistic spectrum disorders, incorporating different language phenotypes is advocated.