There's one tell-tale sign to look out for in your toddler if you want to know if he or she is autistic.
Scientists have discovered that the autistic child won't look at somebody's eyes, but will instead concentrate on the lips and mouth.
They made the discovery when they played 10 different videos to groups of two-year-olds, some of whom were autistic.
The films all featured close-ups, and the autistic children were far more likely than the healthy controls to look at the lips, and not at the eyes, of the actresses.
(Source: Archives of General Psychiatry, 2008; 65: 946-54).