Objectives: (1) To replicate a hierarchy of precursors of imitation in low-risk (LR) controls. (2) To extend the findings to a high-risk (HR) infant sibling sample, compared with LR controls. (3) To examine imitation differences in diagnostic groups (HR/LR) from 9 to 12 months.
Methods: HR and LR participants were evaluated at 9 and 12 months of age using the imitation task from the Autism Observation Scale for Infants (AOSI; Bryson et al., 2008). The AOSI is a semi-structured play schedule that measures early signs of ASD. The examiner presented the infant with 3 actions (oral-facial movements or actions with objects) and 1 to 3 trials per action, depending on the infant’s successful performance. Video records of AOSI administrations were coded using Noldus Observer software and a novel detailed coding scheme. Imitation was scored in 3 ways: (1) total imitation, (2) best score across actions, and (3) approximations to imitation (predictable hierarchical patterns of behavioral responses to the model; e.g., touching model’s hands after model claps).
Results: We compared infants’ imitation scores (i.e., total imitation, best score and approximations to imitation) using 2 (age) by 3 (diagnosis) mixed repeated measure ANOVAs. Infants were grouped according to 36-month outcome as: (1) siblings with ASD (ASD siblings); (2) siblings without ASD (non-ASD siblings); and (3) low-risk controls (LR). Preliminary results from the first 31 infants coded (n’s = 10 ASD siblings, 10 non-ASD siblings, 11 LR) replicated a hierarchy of ‘approximations to imitation’ in the LR group. Further, ASD siblings demonstrated fewer self-directed approximations than the LR controls. As expected, imitation performance increased with age [F (1, 28) = 8.79, p = .006]. A main effect of diagnostic group [F (2, 28) = 3.45, p = .046] revealed that ASD siblings imitated less frequently than did the non-ASD siblings and LR. There was no group by age interaction.
Conclusions: The study provides initial evidence supporting the use of a hierarchy of approximations to imitation as an approach to studying the atypical emergence of imitation skills. Preliminary findings suggest HR-ASD siblings differ from non-ASD siblings and LR controls both in frequency of fully imitative acts and in quality/level of approximations to imitation. These differences are evident by age 9 months and remain at 12 months. The results may have implications for understanding psychological mechanisms underlying the emergence of imitation deficits, and for early detection and intervention in ASD.
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