There is a universal push to screen for ASD at as young an age as possible and growing confidence that the early signs are clear and convincing. Dr. Jose Cordero, the founding director of the National Center on Birth Defects and Developmental Disabilities conveys this fervor.

"For healthcare providers, we have a message that's pretty direct about ASD. And the message is: The 4-year-old with autism was once a 3-year-old with autism, which was once a 2-year-old with autism."

Many researchers are now on the hunt for atypical behaviors cropping up in infancy that could be telltale signs of ASD. For instance, a team of experts led by Dr. Karen Pierce at the Autism Center of Excellence at the University of California, San Diego, has used eye-tracking technology to determine that infants as young as 14 months who later were diagnosed as autistic showed a preference for looking at movies of geometric shapes over movies of children dancing and doing yoga. This predilection for being engaged by objects rather than "social" images is thought to be a marker for autism.

Even the quality of infants' crying has come under scientific scrutiny as a possible sign of the disorder. Dr. Stephen Sheinkopf and some colleagues at Brown University compared the cries of a group of babies at risk for autism (due to having an autistic sibling) to typically developing babies using cutting-edge acoustic technology. They discovered that the at-risk babies emit higher-pitched cries that are "low in voicing," which is a term for cries that are sharper and reflect tense vocal chords. Dr. Sheinkopf, however, cautioned parents against over-scrutinizing their babies' cries since the distinctions were picked up by sophisticated acoustic technology, not by careful human listening.

"We definitely don't want parents to be anxiously listening to their babies' cries. It's unclear if the human ear is sensitive enough to detect this."

What gets lost in the debate is an awareness of how the younger in age we assess for problems, the greater the potential a slow-to-mature kid will be given a false diagnosis. In fact, as we venture into more tender years to screen for autism, we need to be reminded that the period of greatest diagnostic uncertainty is probably toddlerhood. A 2007 study out of the University of North Carolina at Chapel Hill found that over 30 percent of children diagnosed as autistic at age two no longer fit the diagnosis at age four. Since ASD is still generally considered to be a life-long neuropsychiatric condition that is not shed as childhood unfolds, we have to wonder if a large percentage of toddlers get a diagnosis that is of questionable applicability in the first place.

The parallels between a slow-to-mature toddler and a would-be-mildly- autistic one are so striking that the prospect of a false diagnosis is great. Let's start with late talkers. Almost one in five 2-year-olds are late talkers. They fall below the expected 50-word expressive vocabulary threshold and appear incapable of stringing together two- and three-word phrases.