Characterizing the neural signature of face processing in Williams syndrome via multivariate pattern analysis and event related potentials

Emily K Farran,Inês Mares,Michael Papasavva,Fraser W Smith,Louise Ewing,Marie L Smith

doi:10.1016/j.neuropsychologia.2020.107440

Abstract

Face recognition ability is often reported to be a relative strength in Williams syndrome (WS). Yet methodological issues associated with the supporting research, and evidence that atypical face processing mechanisms may drive outcomes ‘in the typical range’, challenge these simplistic characterisations of this important social ability. Detailed investigations of face processing abilities in WS both at a behavioural and neural level provide critical insights. Here, we behaviourally characterised face recognition ability in 18 individuals with WS comparatively to typically developing children and adult control groups. A subset of 11 participants with WS as well as chronologically age matched typical adults further took part in an EEG task where they were asked to attentively view a series of upright and inverted faces and houses. State-of-the-art multivariate pattern analysis (MVPA) was used alongside standard ERP analysis to obtain a detailed characterisation of the neural profile associated with 1) viewing faces as an overall category (by examining neural activity associated with upright faces and houses), and to 2) the canonical upright configuration of a face, critically associated with expertise in typical development and often linked with holistic processing (upright and inverted faces). Our results show that while face recognition ability is not on average at a chronological age-appropriate level in individuals with WS, it nonetheless appears to be a relative strength within their cognitive profile. Furthermore, all participants with WS revealed a differential pattern of neural activity to faces compared to objects, showing a distinct response to faces as a category, as well as a differential neural pattern for upright vs. inverted faces. Nonetheless, an atypical profile of face orientation classification was found in WS, suggesting that this group differs from typical individuals in their face processing mechanisms. Through this innovative application of MVPA, alongside the high temporal resolution of EEG, we provide important new insights into the neural processing of faces in WS.

Highlights

The ability to process faces is critically important for successful social interaction
Our data broadly refute this claim; using the Cambridge Face Memory Test for Children (CFMT-C), we have demonstrated that face processing expertise in adults with WS, as a group, is around the level of typically developing 10-year-olds
The large variability in face processing ability observed in individuals with WS, exceeds that observed in our typically developing (TD) adult group, and is unlikely a reflection of such neurotypical difference

Summary

Introduction

The ability to process faces is critically important for successful social interaction. Are we able to effortlessly recognise a friend, but we can evaluate faces for social cues such as emotion and trustworthiness. Whilst poor visuo-spatial abilities are a hallmark weak ness in this group (Mervis et al, 2000), they show relative proficiency in the face processing domain (e.g., Bellugi et al, 1988). Some have attributed these abilities, at least in part, to the heightened interest in faces observed in WS

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Conclusion