"It could be that the children they could not test would have, if they could have been tested, provided a different set of results," Paul said. "The point is that we would need lots of replication and extension of studies of infant behavior before we could responsibly apply single behavioral measures as diagnostic standards. We should not be too quick to draw conclusions about a difference between a 'normal' group of infants -- from which will usually be excluded lots of fussy, wiggly, uncooperative but otherwise normal babies -- and a group with a single disorder."
A better way to identify diagnostic markers for a particular condition, such as autism, would be to compare infants at risk for autism, such as infant siblings of children already diagnosed with autism, with those at low risk for any disability and with those at high risk, due to family history, or other developmental disorders, Paul said.
"If, for example, infants at risk for autism spectrum disorders [or ASD] show differences in gaze patterns that are similar to those seen in infants with risk for language disorder, it may be that the gaze pattern is more closely related to the language problems that so often accompany ASD than to autism itself," she said.
Perhaps the most important real-world aspect of the study is the importance of visual processing (in addition to auditory processing) in infancy, Camarata said.
"Smiling and talking to the baby are not idle exercises, rather these are the foundation of how babies and children earn to communicate," Camarata said. "Parents should keep their face relatively close to the baby, smile a lot and talk a lot. Keep the engagement going, this is an important part of how a child learns to talk."