The name test indicates when more assessments may be needed

The disorder is usually not diagnosed until a child is three or four, as the symptoms are variable.

However, parents of autistic children often say they have noticed early tell-tale behaviour.

The 'name test' described in Archives of Pediatrics and Adolescent Medicine appeared to aid earlier diagnosis.

Simple screen

The researchers studied two groups of infants - a healthy control group and a group of children deemed to be at higher than normal risk of autism because they all had older siblings with the condition.

At 12 months, all of the 46 infants in control group passed the name test, responding on the first or second call of their own name, while only 86% of the 101 'at risk' infants passed. The University of California Davis, Sacramento, team followed 46 of the 'at risk' infants and 25 of the controls up to their second birthday.

Three-quarters of the 'at risk' children who had failed the name test were found to have developmental problems at the age of two.

Of the children who were later diagnosed with autism, half had failed the name test at one year, and of those who were identified as having any type of developmental delay, 39% had failed it.

Aparna Nadig and colleagues had tried the name test on the children when they were only six months old, but found this was too young an age to get any meaningful result.

Routine check

They stressed that if the name test were to be used routinely, it should not be relied on solely to diagnose autism - it merely indicates that a child may need more assessments.

Equally, a child who fails the test will not necessarily have autism.

However, one who fails repeatedly and consistently has a high likelihood of some type of developmental abnormality and should be referred for further checks and possibly early intervention, they said.

Judith Gould of the National Autistic Society said there was good evidence that early intervention could help.

But she also cautioned: "Just because a baby does not respond to their name does not necessarily mean that he or she has autism.

"The diagnostic assessments for autism are thorough and wide-ranging, taking into account a variety of other factors such as eye contact, pointing and showing.

"If parents are concerned about their child's development, they should call the NAS helpline on 0845 070 4004 or seek the opinion of a medical professional."