It’s often assumed that people with autism who are nonspeaking do not know how to read or write, but new research suggests that for many individuals that may not be the case.

A study published recently in the journal Autism finds that five times more teenagers and adults with autism who are nonspeaking have knowledge of written language than was expected.

“Society has traditionally assumed that people who can’t speak are unable to understand language or to learn to read or write,” said Vikram Jaswal, a professor of psychology at the University of Virginia who led the study. “But our findings suggest that many nonspeaking autistic people have foundational literacy skills.”

For the study, researchers looked at 31 teens and adults with autism. Friends or family members completed three different standardized measures assessing social communication, adaptive behavior and social responsiveness.

Participants ranged from those who could speak no words to individuals with a few words or phrases, but all were considered by their families to be nonspeaking and could not effectively communicate with speech. The assessments showed them to be “significantly disabled,” the study found.

Each of the individuals with autism was asked to tap on an iPad as various letters flashed on the screen. In some cases, the letters appeared in a random sequence, but sometimes they spelled out sentences that the participants had previously heard spoken aloud but had not seen visually. Researchers then assessed the participants’ response times.

More than half of the participants responded in the same way as a person who is literate, the study found. This was the case even though most of the participants involved in the research had not had formal instruction in reading or writing.

“Our study shows that nonspeaking autistic people’s capacity for language, for learning and for literacy has been seriously underestimated,” Jaswal said. “With appropriate instruction and support, it might be possible to harness these skills to provide access to written forms of communication as an alternative to speech. Learning to express themselves through writing would open up educational, employment and social opportunities that nonspeaking autistic people have historically not been given access to.”