Infants' Repetitive Behaviour, Locomotor Development and Social-Communication Abilities

Background: By definition repetitive behaviours are considered to be symptoms of ASD, and are highlighted as potential indicators for ASD in current clinical practice. They represent one third of Wing and Gould’s (1979) triad of impairments and are an essential part of diagnosis. Repetitive behaviours are commonly seen amongst typically developing infants; however, little information exists concerning normal variation amongst repetitive behaviours in community samples. It is imperative to understand repetitive behaviours from a broader developmental context in order to establish normative trends and frequencies.

Objectives: The present study of a nationally representative community sample addresses three main questions:  (1) Are older infants less likely to use repetitive behaviours?  (2)  Are infants with more advanced motor development less likely to use repetitive behaviours?  (3)  Are repetitive behaviours negatively or positively associated with infants’ social and communicative skills?

Methods: Repetitive behaviours were recorded in a sample of 243 11- to 14 month-old infants. Observational methods were used to record instances of two categories of repetitive behaviours (motor stereotypies and repetitive manipulation of objects) during free play and infants’ turn-taking abilities with an examiner.  Parents reported on the infants’ motor development.

Results: Repetitive motor actions were negatively and significantly associated with age in months, locomotor ability and turn-taking abilities. Repetitive object manipulation was not associated with age, maturation or social skill.

Conclusions: The present findings allow us to begin to place repetitive behaviour within a normative development context which will inform studies of high-risk infants. The present cross-sectional findings suggest there might be a normative decline in motor stereotypies between 11 and 14 months but no similar decline in repetitive manipulations on objects, which remain common in typically developing one-year-olds. These cross-sectional data need to be confirmed in longitudinal analyses.  However, the higher rates of motor stereotypies shown by infants with less mature locomotor and social skills suggests the continued use of repetitive motor actions in the second year of life might possibly be a sign of developmental delay and problems in social interaction relevant to ASD.  In contrast, in this sample, repetitive operations on objects were age-normative, and not associated with motor immaturity or lack of social skill. Thus repetitive exploration of objects is not likely to be informative for attempts to identify early signs of ASD in this age range. Future attempts to diagnose ASD in the toddler years should distinguish between the two categories of repetitive behaviour.