The Emergence of Imitation: Preliminary Findings From a Prospective Study of Younger Siblings of Children with Autistic Spectrum Disorders

Background: Imitation deficits are well documented in autistic spectrum disorders (ASD; Rogers & Williams, 2006). Indeed, imitation deficits are among the predictors of ASD by as early as 12 months of age (Zwaigenbaum et al., 2005) and accuracy of early imitation is reduced in infants at risk for ASD (Young et al., 2011). However, little is known about the atypical, versus typical emergence of imitation. That is, few studies have examined qualitative differences in pre-imitative behavior (approximations to imitation, Kaye & Marcus, 1981; Nichols, 2005). Further, no infant sibling study has examined emerging imitative abilities as early as 9 months.

Objectives: (1) To replicate a hierarchy of precursors of imitation in low-risk (LR) control 9-month-olds. (2) To extend the findings to a high-risk (HR) infant sibling sample, compared with low-risk controls.

Methods:   HR and LR participants were evaluated at 9 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 (Bryson et al., 2008). Each infant sat on a parent’s lap, facing an examiner across a small table. 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 9-month 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) between groups using 3 one-way 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 30 infants coded (n’s = 8 ASD siblings, 10 non-ASD siblings, 12 LR) replicated a hierarchy of ‘approximations to imitation’ in the LR group. Further, ASD siblings demonstrated fewer self-directed approximations than the LR controls.  Finally, the ASD siblings imitated less frequently across actions (e.g., best score) than did the non-ASD siblings and LR [F (2, 27) = 3.72, p = .037].

Conclusions:   The study provides initial evidence supporting the use of a hierarchy of approximations to imitation as a novel approach to studying the atypical emergence of imitation skills.  Preliminary findings suggest HR siblings differ from LR controls both in frequency of fully imitative acts and in quality/level of approximations to imitation.  Moreover, these differences are evident by age 9 months. The results may have implications for understanding psychological mechanisms underlying the emergence of imitation deficits, and for early detection and intervention in ASD.