Motor Development, Autism Symptoms, and Emerging Executive Functioning in Infants and Toddlers at High and Low Risk for ASD

Background: The A-not-B task, developed by Piaget, is one of the classic tests of human cognitive development and has been used widely in developmental research. This task is based on the theory of object permanence and is purported to measure working memory, response inhibition, and goal-directed behavior. Ability to perform the A-not-B task requires acquisition of specific motor milestones (e.g., reaching and grasping). Furthermore, research suggests that motor abilities and executive functioning are associated. However, relationships between abnormal early motor ability, impaired performance on the A-not-B task, and later development of autism symptoms in a high-risk (HR) sample having an affected older sibling are not well understood.

Objectives: To assess whether performance on the A-not-B task at 12 and 24months is associated with motor development and autism symptoms. We hypothesize that 1) better motor skills will be associated with better performance on the A-not-B at both 12 and 24months and 2) toddlers who develop autism symptoms at 24months (HR-ASD-Positive) will perform worse on the A-not-B at 12 and 24months than those without autism symptoms (HR-ASD-Negative, LR-ASD-Negative).  

Methods: Participants are part of a multi-site, longitudinal study of brain and behavioral development in infants at high-risk (HR) and low-risk (LR) for ASD followed from 6months and assessed for autism symptoms at 24 months (HR-ASD-Positive, n=34; HR-ASD-Negative, n=133; LR-ASD-Negative, n=69). A-not-B data was collected at 12months (n=291) and 24months (n=226).  In the A-not-B task, the infant watched as a toy was hidden to the left or right of midline. The infant was encouraged to find the toy after a delay of either 5s or 12s. Once the infant found the hidden toy on two consecutive trials, the side of hiding was switched. A maximum of 24 trials were administered. Performance was measured by the percentage of accurate reaches/errors at each delay interval. Motor skills were assessed with the Mullen Scales and Vineland. Autism symptoms were assessed using the ADOS and DSM at 24months.  

Results: Preliminary results revealed that nearly one-third of HR and LR 12-month-olds had unusable A-not-B data and one-quarter had unusable data at 24months. These children had lower fine motor skills at 12 months and lower fine and gross motor skills at 24 months as compared with children with useable A-not-B data. The groups (HR-ASD-Positive, HR-ASD-Negative, LR-ASD-Negative) did not differ on A-not-B performance at 12 months. At 24months, the HR-ASD-Positive group demonstrated significantly lower total percent correct than the LR-ASD-Negative group. The HR-ASD-Negative group demonstrated significantly decreased performance (percent correct reversal at 5s, total reversal errors, and total percent correct) as compared with the LR-ASD-Negative group. Further analyses will investigate the interaction between group, motor ability, and A-not-B performance and the role of overall cognitive ability in A-not-B performance. 

Conclusions: Preliminary evidence suggests that difficulties on the A-not-B task at 12 and 24months may be associated with motor ability at 12 and 24 months, with autism symptoms at 24months, and with autism risk status. Future studies should evaluate possible causal pathways between early motor deficits and later outcomes in ASD.