Breadth and Continuation of Object Exploration Are Impacted By ASD Risk and Motor Ambition

Background:  

School-age children with Autism Spectrum Disorders (ASD) exhibit particular difficulty with hand-eye coordination and appear to be less sensitive to visual feedback during motor learning. Estes et al. (2015) note that differences in sensorimotor behavior at 6-months-of-age between infants at high (HR) and low (LR) for autism are informative of continued developmental trajectory and later expressed autism phenotype. This echoes the importance of identifying early fine and gross motor deficits in children with ASD (Landa, 2008). Typically, self-initiated reaching leads to longer exploration of, more interest in, and more multimodal engagement with objects (Needham, et al., 2002). Motor deficits in infancy impacting self-initiated actions affect the extent of learning and growth which occurs during the active interaction (Gibson & Pick, 2000), in part because this quality of the interaction determines the kind of information (e.g., shape, texture, or weight) that can be obtained about the object (Bushnell & Boudreau, 1993). 

Objectives:  

Evaluate continued interest in object exploration expressed over trials of a novel ball catching task, assessed against autism risk and motor ambition (determined as anticipating ball arrival).

Methods:  

Six-month-old infants (n=107, 64 HR and 43 LR) participated in the study. Video recordings of the ball rolling sub-task from the Autism Observation Scale for Infants (AOSI) were coded for the following object exploration behaviors: attempt to grasp, lift, anticipation of mouthing, mouthing (after lift or by leaning down), shaking, patting, banging, rolling, hand transfer, and dropping ball on table or floor. For each of 3-trials, we counted object exploration (OE, the total # of behaviors) and new behaviors (NB, those not previously performed). Anticipation was coded according to whether any manual action was expressed in response to the approaching ball on the first trial. A 3-way mixed-model MANOVA (Trial × Risk × Anticipation) was performed, with pairwise comparisons to identify where differences occurred (alpha=0.05).

Results:  

No differences were found in the total number of OE behaviors, for any factor or interaction. For NB, a main effect of Trial was identified (F­_2,206­=40.0, p<0.001, η_p²=0.280), with follow-up indicating fewer new behaviors on subsequent trials. Additionally, Risk × Anticipation (F­_1,103­=6.26, p=0.014, η_p²=0.057) and Trial × Anticipation (F­_2,206­=5.24, p=0.006, η_p²=0.048) interactions were found. Follow-up to the Trial × Anticipation interaction suggests that non-Anticipators showed more new behaviors on the second trial compared to Anticipators and then much fewer on the third. Follow-up to the Risk × Anticipation interaction indicates that HR non-Anticipators showed the fewest NB.

Conclusions:  

Six-month-old infants sought to develop a robust repertoire of exploratory behaviors and continued to take advantage of new object exposures by adding new strategies on subsequent trials. However, across all children, the number of new strategies declined with each new opportunity. HR and LR infants who anticipated the ball displayed similar object exploration behavior across trials and showed more OE on the first trial than did non-anticipators. Interestingly, non-anticipating LR infants demonstrated more NB than anticipatory infants on the second trial, while non-anticipatory HR infants demonstrated consistently fewer new behaviors, especially on the first trial.