Infant girls at an elevated risk for autism pay more attention to social cues in faces than do boys at the same risk1. The finding may help to explain why girls with autism tend to have subtler symptoms than boys with the condition.

Researchers have long suspected that genetic factors guard girls against autism. The new study suggests cognitive elements help shore up the gender shield.

“For the first time, we show that infant girls at risk for autism have very unusual attention to social stimuli,” says lead researcher Katarzyna Chawarska, director of the Early Social Cognition Laboratory at Yale University. “This might protect against development of social difficulties and put high-risk girls on a different trajectory than high-risk boys.” Chawarska’s team published the results 15 December in the Journal of the American Academy of Child & Adolescent Psychiatry.

Autism is thought to affect roughly four boys for every girl, and girls with the condition tend to have fewer repetitive behaviors and social problems than affected boys do. The new study raises the possibility that skills learned in infancy help girls sidestep severe autism symptoms later in life.

“This is a milestone study,” says Meng-Chuan Lai, assistant professor in psychiatry at the University of Toronto. “It demonstrates what mechanisms in cognitive development may be associated with, or even partly underpin, the female protective effect of autism.”