Question: Why are some parents holding their babies in front of mirrors and tilting them sideways?

Answer: They're testing for Asperger's syndrome, an autistic spectrum disorder, by holding infants 6 to 8 months old at the waist and tilting them 45 degrees. Two University of Florida researchers say normally developing babies try to hold their heads perpendicular to the floor, while babies with Asperger's keep their heads aligned with their bodies. Since Philip and Osnat Teitelbaum -- respectively, a PhD in physiological psychology and a specialist in movement notation -- told "Good Morning America" last month that the tilting test should be performed on all infants beginning at 6 months, their study -- which appeared in the July 28 Proceedings of the National Academy of Sciences -- has received worldwide media attention.

Why the Interest? Asperger's syndrome -- typified by problems in social functioning, repetitive routines, idiosyncratic interests, normal to high IQ and, often, clumsiness -- is usually not diagnosed until age 6 through 8. Psychologists estimate that two to four of every 1,000 people have Asperger's, and the number diagnosed is growing every year. If the problem could be identified sooner, say researchers, treatment could begin earlier.

But Wait Yale psychiatrist Fred Volkmar, one of the world's leading experts on autism and Asperger's syndrome, calls the study "potentially interesting" but flawed: The sample was small, the researchers never examined the infants in person and the study wasn't blinded. The Teitelbaums based their analysis on videotapes of just 16 babies, sent in by parents who said their children were later diagnosed with Asperger's. Researchers knew while they were watching the tapes that these infants had later been diagnosed with Asperger's (which in theory could have influenced their interpretations of what they observed) and there was no independent confirmation of the children's diagnoses. Philip Teitelbaum said the team next plans to screen infant siblings of children with autism; the goal will be to predict, via the tilt test, which ones will later be diagnosed with autism or Asperger's.

-- Lisa Barrett Mann

The System will return next week.

Baby's head position indicates, at left, normal development; at right, Asperger's syndrome, suggests a study.