When babies age 9 months or older examine objects in unusual ways, this could be an indication they will develop autism later on.

Many children with autism spectrum disorder (ASD, or, simply, autism) tend to focus obsessively on visual details and engage in repetitive visual behaviors. Now, new study findings published in the Journal of Abnormal Psychology show that this hallmark symptom of the disorder can manifest in kids as young as 9 months old, reports a press release from the University of California, Davis Health (UC Davis Health).

Known as a spectrum disorder because of the wide variation in the type and severity of symptoms, autism occurs in all racial, ethnic and socioeconomic groups. The developmental disorder can be diagnosed at any age, but symptoms usually appear by age 2 and affect children’s behavior and ability to communicate.

For the study, researchers used videos to assess two groups of children for visual inspection, repetitive behavior and social engagement. One group of 89 infants with older siblings who had autism made up the high-risk group. (Younger siblings of children with autism are diagnosed at a rate of 1 in 5.) The low-risk group consisted of 58 infants whose older siblings did not have autism.

Scientists tracked the various ways individual youngsters played with objects—notably, how often and long the kids inspected, spun or rotated objects—at 9, 12, 15, 18, 24 and 36 months old and ranked each child’s social engagement behavior, as defined by how frequently the child made eye contact and smiled at others and overall social responsiveness.

At 36 months, researchers divided the children into three categories: Low-Risk Non-ASD (58 children), High-Risk Non-ASD (72 children) and Diagnosed with ASD (17 children).

Results showed that unusual visual inspection behavior was exhibited earliest, most noticeably and regularly in children diagnosed with autism. In addition, at age 9 months, these infants displayed this unusual behavior more often than those in both other groups and continued to exhibit it at increased rates at all ages.

Researchers explained that unusual visual inspection of objects is present and stable in infants developing ASD by 9 months and this also forecasted decreased social engagement three months later.

“An increased focus on objects early in life may have detrimental cascading effects on social behavior,” said Sally Ozonoff, PhD, a professor in the department of psychiatry and behavioral sciences and the MIND Institute at UC Davis and the study’s principal investigator. “Findings from our study suggest that unusual visual exploration of objects may be a valuable addition to early screening and diagnostic tools for ASD.”

To learn more about autism in kids, read “Delays in Autism Diagnoses Especially Harmful to Black Children.”