The process of acquiring skills related to social interaction and communication may vary from child to child. A specialist will only consider a diagnosis of autism spectrum disorder if there is a clear and persistent deviation from expectations in these areas. It is important to remember that in some toddlers the reason for difficulties in social interactions is shyness or behavioural inhibition (i.e. slow “warming up” to new people and situations). Limited social interactions in such individuals do not indicate autism.

The child’s speech also develops at a variable rate. Its delay alone does not indicate autism, unless the child also shows limited motivation for social communication and limited interaction skills.

Furthermore, repetitive behaviours or limited interests by themselves do not indicate a disorder. For a diagnosis of ASD to be made, they should be accompanied by impaired social interaction and communication.