Interdependence of Autistic Traits Within and Beyond the Spectrum INTERDEPENDENCE OF AUTISTIC TRAITS WITHIN AND BEYOND THE SPECTRUM Detail-Oriented Cognitive Style and Social Communicative Deficits, within and beyond the Autism Spectrum: Independent Traits that Grow into Developmental Interdependence

At the heart of debates over underlying causes of autism is the “Kanner hypothesis” that autistic deficits in social reciprocity, and a cognitive/perceptual „style‟ favouring detail-oriented cognition, co-vary in autistic individuals. A separate line of work indicates these two domains are normally distributed throughout the population, with autism representing an extremity. This realisation brings the Kanner debate into the realm of normative co-variation, providing more ways to test the hypothesis, and insights into typical development; for instance, in the context of normative functioning, the Kanner hypothesis implies social costs to spatial/numerical prowess. In light of this growing body of research, we review relevant factor analytic and correlational, behavioural studies. Findings are then synthesised into three themes: an alternative triad of primary autistic trait categories – Social Interaction Deficits, Cognitive Inflexibility, and Sensory Abnormalities – that more accurately reflects the factor structure of autistic traits; continuity between clinical and non-clinical autism-spectrum trait presentation; and indications that although social and non-social autistic traits may be initially independent, Kanner-like covariance emerges behaviourally from dynamic trait interactions over the course of development. A dynamic developmental model subsuming these patterns is offered, and its advantages demonstrated in a novel account of ritualistic behaviours: as developmentally emergent, compensatory mechanisms for interactions between cognitive inflexibility and sensory abnormalities. We conclude with the broader imperative that behavioural scientists appealing for directly and exclusively genetic links may instead benefit from a developmental framing within their own discipline. (242 words)