Repetitive behaviours in typically developing 2-year-olds.

BACKGROUND Repetitive behaviours are an essential part of the diagnosis of autism but are also commonly seen in typically developing children. The current study investigated the frequency and factor structure of repetitive behaviours in a large community sample of 2-year-olds. METHODS A new measure, the Repetitive Behaviour Questionnaire (RBQ-2) was completed by 679 parents. RESULTS The RBQ-2 had good psychometric properties. A four-factor model provided the best fit for the data, accounting for 51% of the variance, and suggested 4 sub-scales: unusual sensory interests, repetitive motor movements, rigidity/adherence to routine and preoccupations with restricted patterns of interest. These sub-scales closely resembled repetitive behaviour subtypes within the ICD-10 criteria for autism. Repetitive behaviours of every type were frequently reported. Higher scores were found for all children, and especially boys, on the subscale relating to preoccupations with restricted patterns of interests. CONCLUSION The results support the proposal that repetitive behaviours represent a continuum of functioning that extends to the typically developing child population.