The eyes or the mouth? Feature salience and unfamiliar face processing in Williams syndrome and autism

Abstract

Using traditional face perception paradigms the current study explores unfamiliar face processing in two neurodevelopmental disorders. Previous research indicates that autism and Williams syndrome (WS) are both associated with atypical face processing strategies. The current research involves these groups in an exploration of feature salience for processing the eye and mouth regions of unfamiliar faces. The tasks specifically probe unfamiliar face matching by using (a) upper or lower face features, (b) the Thatcher illusion, and (c) featural and configural face modifications to the eye and mouth regions. Across tasks, individuals with WS mirror the typical pattern of performance, with greater accuracy for matching faces using the upper than using the lower features, susceptibility to the Thatcher illusion, and greater detection of eye than mouth modifications. Participants with autism show a generalized performance decrement alongside atypicalities, deficits for utilizing the eye region, and configural face cues to match unfamiliar faces. The results are discussed in terms of feature salience, structural encoding, and the phenotypes typically associated with these neurodevelopmental disorders.

Keywords:

• Autism
• Williams syndrome
• Face processing
• Eyes

Notes

1 A sample size of 15 is comparable to published research including participants with WS, for example Karmiloff-Smith et al. (2004).

2 A sample size of 20 is comparable to previous research exploring face processing in autism, for example Deruelle et al. (2004).

3 Pilot testing revealed that for typically developing children aged 6–10 years (n = 88) eyes moved by 9 pixels were detected approximately 62% of the time, and mouths moved by 6 pixels were detected with 61% accuracy.

4 It is not appropriate to directly compare performance for the autism and WS groups as they were not matched due to the rarity of the developmental disorders and participant availability.

5 Reaction time data were also collected for some groups; however, accuracy data proved more reliable due to large variances within and between groups, low accuracy, and participant characteristics.