A new study has linked when and why children blink to autism, a developmental disorder that affects the ability to communicate and relate to others. Toddlers with autism focus on movement, whereas others focus on emotions, researchers say in a study published in the Proceedings of the National Academy of Sciences.

“The more engaged you are, the less likely you are to blink,” said senior study author Warren Jones, director of research at the Marcus Autism Center in Atlanta.

Among nearly 100 toddlers who were tested while watching a video, those with an autism spectrum disorder blinked less during scenes involving movement, while typically developing children blinked less during emotional interaction in the video.

When blinking, your eyes are closed and you lose some pieces of information, Jones explained. Not blinking is a sign that kids find the information most important, engaging or relevant. Earlier research has found that kids with autism pay less attention to social cues, he added.

Kids with autism pay more attention to objects than people, says Geraldine Dawson, chief science officer for Autism Speaks. “However, this is the first study to my knowledge that has used blinking to assess how engaged a child is with what he or she is viewing.”

These findings suggest that blinking patterns may be used to measure the success of autism therapies.

One in 110 children in the U.S. has an autism spectrum disorder, according to the U.S. Centers for Disease Control and Prevention.