Signs of autism may be apparent in children as young as six months, new research suggests.

In looking at more than 100 infants, researchers at the Yale School of Medicine found that those who would later develop autism were already showing deficits in social attention at just six months of age.

For the study, the babies were monitored with eye tracking technology while they watched a three-minute video of a woman doing various tasks. The actress is shown making a sandwich, looking at toys and at other points she speaks directly to the viewer. The children were then clinically assessed for an autism diagnosis three years later.

Ultimately, kids who were diagnosed with autism had spent less time looking at the social scene in the video and were less likely to look at the woman’s face than other study participants who did not develop autism, the researchers report in the journal Biological Psychiatry.

“This study highlights the possibility of identifying certain features linked to visual attention that can be used for pinpointing infants at greatest risk for ASD in the first year of life,” said Katarzyna Chawarska, an associate professor at the Yale Child Study Center, who led the study. “This could make earlier interventions and treatments possible.”