Differential Habituation to Social Scenes in Toddlers with ASD, Non-ASD Developmental Delays, and No Delays

Background:   Studies have shown slowed rates of behavioral and neural-based habituation to static facial stimuli in individuals with autism spectrum disorder (ASD) across the lifespan. Slowed rates of habituation to faces in toddlers is associated with more symptoms; however, little is known about habituation to other kinds of social stimuli and how habituation rates compare to toddlers with non-ASD delays. Such data may be useful in identifying early behavioral markers of ASD and informing targeted interventions.

Objectives:   The current study examines whether differences emerge in behavioral habituation during a dynamic social attribution task between children with ASD, non-ASD developmental delays (DD), and those without developmental delays (TD). This study also aims to examine whether these differences are moderated by modality of task presentation (i.e., puppet show vs. computerized cartoon) given studies suggesting that computerized learning may be more effective for children with ASD than live-based learning.  

Methods:  This preliminary sample included 18 toddlers (16 male, m_age=22.7mo, SD=3.7), six with ASD, seven with DD (i.e., language disorder or global developmental delay), and five typically developing (TD).

Toddlers were presented with both a live puppet show and computerized cartoon (order counterbalanced) of alternating helping and hindering social scenes featuring geometric shapes (10s each) on separate days. Scenes were presented until habituation criterion was reached (i.e., the sum of looking time on three consecutive presentations is less than half of the sum of the looking time on the first three presentations, with a maximum of twelve presentations). 

Results:  The pattern of findings suggest that children in the ASD and DD groups require additional habituation trials in the puppet version (ASDm_trials=10.5, SD=2.5; DDm_trials=9.9, SD=2.8) compared to the TD group (m_trials=7.8, SD=1.6) whereas all groups require a similar number of trials in the computerized version (ASDm_trials=8.5, SD=2.3; DDm_trials=9.0, SD=2.4; TDm_trials=9.0, SD_trials=3.0). Additionally, data suggest that children with ASD look longer at the puppet scene during habituation (m_time=82.9, SD=2.3), compared to the DD and TD groups (DDm_time=67.6, SD=42.9; TDm_time=56.8, SD=36.3), but that this difference is absent during the computerized version (ASDm_trials=62.9, SD=28.5; DDm_trials=68.0, SD=30.8; TDm_trials=81.7, SD=58.4). Effect sizes for the interaction between diagnosis and modality (puppet vs. cartoon) for the number of habituation trials and total looking time were medium (η_p²=.12) and large (η_p²=.94), respectively. Not surprisingly in this small sample, conventional levels of statistical significance were not reached; however, medium to large effects suggest that significant differences will emerge as additional children are recruited.

Conclusions: Preliminary findings suggest that there may be differential behavioral habituation rates to non-facial social stimuli, and that this may be moderated by the modality in which stimuli are presented. More data are needed to examine whether these medium to large effects become significant. Future research should compare habituation rates of social vs. nonsocial stimuli in these groups and modalities and explore the utility of behavioral habituation as an early behavioral marker of ASD.