Reduced Left Cradling Bias and Cerebral Lateralization in Children with ASD

Background: Previous studies have indicated a maternal preference to holding infants on the left side of their body. The physical positioning is thought to facilitate the processing of social-emotional stimuli by establishing a direct route to the right hemisphere. Reduced cortical lateralization has been associated with ASD and whilst disruption to left cerebral lateralization for fine motor dominance is associated with weaker language acquisition in young children, the ramification of disruption of right cerebral lateralization associated with social-emotional processing has yet to be explored within the scope of cognitive development.

Objectives: To examine right cerebral lateralization of processing social stimuli through the left cradling bias in children with ASD and typically developing controls.

Methods: 60 4-6-year old children with ASD were compared with 80 control children in a cradling task consisting of three different holding conditions; participants cradled a lifelike human baby doll or a control object of an equivalent weight and dimension either with or without symbolic facial features. Handedness was also assessed across three motor tasks interspersed with each cradling trial.

Results: The control group demonstrated a significant left side preference when holding the human doll. Whilst a left side bias was not demonstrated when the group cradled the control object without social features, the addition of rudimentary facial features was sufficient to elicit a left holding bias. Conversely, no preference for left cradling was evident in the ASD group for any doll type and no significant difference was identified between the holding preference of social and non-social objects. Furthermore, stronger hand dominance was positively correlated with a left cradling bias overall.

Conclusions: We identified the absence of a left cradling bias as a possible indicator of atypical cerebral lateralization in children with ASD. Findings support the possibility that socialisation influences cerebral lateralization for processing social-emotional stimuli in typical development, whereas children with ASD did not distinguish between social and non-social stimuli.