A major study may have just made an important breakthrough when it comes to autism and how to spot it.

Researchers used special technology to monitor the eye movements of 18 autistic children between 6 and 12 years of age and 19 children who did not have autism, according to a University of Vermont statement.

The study found that children who had autism tended to focus more on the mouth of the speaker than the eyes when it came time to talk about their feelings. The research also showed that this practice was more prevalent in children who had severe autism.

Why do autistic children do this? It’s not really clear, but it may be that conversations tend to strain the executive function of those who have autism. Emotional topics tend to strain working memory in the brain, which makes it hard to get information from the eye region, so the child looks elsewhere for information.

The findings could lead to speech therapy treatments for children with autism.

“What you talk about really matters for children with ASD,” lead author Tiffany Hutchins, assistant professor of communication sciences and disorders, said in the statement. “You just change a few words by talking about what people do versus how they feel and you can have a profound impact on where eyes go for information.”

She added: “It’s probably a situation where the poor are getting poorer. If I’m asking you to talk about emotions, and that makes you even less likely to look in my eyes when you really need to go there because I’m more likely to be showing other evidence of an emotion like anger with my eyebrows, you are missing even more. It’s not that there’s no emotional information in the mouth, but during dynamic conversational exchanges they are missing a number of cues that a typically developing child would not.”