Declining eye contact during the first few months of life may be a key to identifying children likely to develop autism.

Babies typically focus on faces almost as soon as they are born, and learn to pick up social cues by looking at other people's eyes. Children with autism, a developmental disorder characterized by impaired social interaction and communication skills, rarely make eye contact.

In a study funded by the National Institute of Mental Health, researchers used eye-tracking equipment to measure eye movements as children watched images of a caregiver, noting how often they looked at the face, the body and other objects. The sessions were conducted 10 times over two years.

Autism is not usually diagnosed until after age two. By age three, the eye-tracking data showed those youngsters with autism had focused less and less on the caregiver's eyes as the study progressed.

The researchers say that suggests autistic children are born with social skills intact, and by identifying early signs of social disability, interventions could "help reduce some of the associated disabilities that often accompany autism."

The research team's findings are reported in the journal Nature.