Abstract
Children with autism spectrum disorder (ASD) and intellectual disabilities (ID) present with problem behaviour at rates disproportionately higher than their typically-developing peers. Problem behaviour, such as self-injury, aggression, pica, disruption, and elopement result in a diminished quality-of-life for the individual and family. Applied behaviour analysis has a well-established research base, detailing a number of assessment and treatment methods designed to address behaviour problems in children with ASD and ID. Although the variables that lead to the emergence of problem behaviour are not precisely known, those that are currently responsible for the maintenance of these problems can be identified via functional behaviour assessment, which is designed to identify events that occasion problem behaviour, consequences that maintain it, as well as other environmental factors that exert influence on the behaviour. Corresponding function-based treatment is implemented when environmental determinants are identified, with the aim of decreasing or eliminating problem behaviour, as well as teaching the individual to engage in more appropriate, alternative behaviour. In some cases, when problem behaviour is under the control of both environmental and biological variables, including psychiatric conditions, combining behavioural and pharmacological interventions is viewed as optimal, although there is limited empirical support for integrating these approaches.