Habituation Speed and Novelty Preference to Faces in Preschoolers with ASD

Background:  

Impairments in face processing and recognition may be apparent in the early development of ASD, with toddlers aged 18 to 30 months with severe symptoms of ASD needing more time to habituate to faces than comparison groups (Webb, Jones et al. , 2010).  Differentiation of familiar vs. unfamiliar faces is also delayed in ASD at this age, with the delay related to the degree of social adaptive delay (Webb et al., 2011).

Objectives:  

To assess the influence of facial familiarity on behavioral measures of face processing and memory impairment in preschoolers aged 24 to 48 months with ASD symptoms. 

Methods:  

Two groups were tested: preschool aged children with ASD (N=61) and preschool aged children with typical development (N=61).  In addition to diagnostic and developmental testing, each child took part in four habituation experiments, in a two stimulus (Face, Object) by two stimulus set (Set A, Set B) design across 2 visits.  Children viewed a picture of a face or a toy until they met a habituation criterion; after a delay, children viewed the familiar picture and a novel picture. Variables included time to habituate, number of looks during habituation, and novelty preference.  Faces were rated for similarity to the mother’s face. As two different face sets were used (A / B), we compared habituation variables when the face set was similar vs. dissimilar to mother’s face.

Results:

Total time, mean look, first look and total number of looks for habituation to faces was similar in both the ASD and TYP groups (Fs<.49, ps>.4). The look to the novel face was shorter for the ASD than TYP group (F=3.8, p=.05) although both groups (F=.385, p=.53) demonstrated a novelty preference (ts>27, ps< .01). There was no difference between habituation variables and Visit Order (F<1.9, ps>.17) nor Face Set (Fs<.13, ps>.26). Preliminary modeling of familiarity (based on hair style/color match) suggests that match to mom’s face may influence total time to habituation and length of first look differentialy in the ASD group vs TYP group (Group x Similarity interaction: Fs<2.9, ps<.09) in our set of faces that had long hair (Set A).

Conclusions:  

Habitation patterns may provide important information about early attention skills in children with ASD. We have suggest that attention, particularly social attention, is critical in supporting more complex social learning. Thus, altered learning about faces may be an important target of early interventions. Our preliminary analyses suggest that the overall pattern of attention to faces is normative between 2 and 4 years of age but that attention to the novel face after habituation and the influence of facial similiarity/familiarity may alter attention patterns by group.