Slide 7

Perhaps the most striking and perplexing aspect of autism's pattern of restricted interests and repetitive behaviours is their lack of apparent purpose or function.

A child with autism may spend hours flicking a light switch, or flushing a toilet, or calculating calendar dates, any procedure that offers a predictable and repeatable output.

Persons with autism can react with anxiety or frustration to interference with these compulsions, or to minor changes in environment or routine.

Restricted interests and skills often are not generalised to apply to new problems. For example, a calendar calculator may have no interest in other forms of arithmetic calculation.

People with autism may develop abnormal and specific sensory fascinations, for example the sight of a bicycle reflector or the smell of diesel exhaust.

They tend to restrict their attention to parts of objects, for example spinning the wheels of a toy instead of using the whole toy as intended.

There are motor stereotypies, such as hand-flapping and finger-flicking.

And finally, there can be emotional attachments to unusual objects, for instance holding a wire brush instead of a teddy bear.