Habituation Speed and Novelty Preference to Faces Differ in Toddlers with ASD Compared to Infant Siblings, and Controls

Background:

Processing information from faces is a component ability of many of the social skills that are impaired in young children with ASD.  Impairments in face processing and recognition may be apparent in the early development of individuals with ASD.  

Objectives:

To assess whether toddlers with ASD show specific impairments in face processing and memory, and whether these deficits are related to their ASD symptoms. 

Methods:

Four groups were tested: toddlers with ASD, typically developing toddlers, toddlers with developmental delays, and non-symptomatic toddlers with an older sibling with ASD.  In addition to diagnostic and developmental testing (including the ADOS, ADI-R Toddler and the Mullen Scales of Early Learning), each toddler took part in four habituation experiments, in a 2 stimulus (face, house) by 2 delay (5 seconds, 5 minutes) design.  Toddlers viewed a picture of a face or a house until they met a habituation criterion.  After a delay, toddlers viewed the familiar picture and a novel picture.  Time to habituate and preference for novelty were calculated.    

Results:

Toddlers with ASD took significantly longer to habituate to faces than the other groups (p<0.05); both toddlers with ASD and siblings of children with ASD took longer to habituate to houses (p<0.05).  Toddlers with ASD showed less attention to the novel face than other toddlers after a 5-minute delay (p<0.05).   Longer habituation times to faces (but not houses) correlated with lower scores on the ADOS and the Mullen (p<0.05). 

Conclusions:

Slower learning about faces and poorer face memory may be specific features of ASD in toddlerhood, and are related to social and communicative difficulties in ASD.