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An Autism Mystery: Why is Speech Elusive for Some on the Spectrum?

Marina Sarris

Date Published: July 10, 2020

Joan Drebing waited for those first words from her twin babies. Just as infants have an inborn drive to learn to talk, parents seem programmed to take delight in hearing their children’s voices for the first time. Although her daughter began speaking, Drebing’s son, Ryan, seemed stalled at “mama.” When he was 3, his family learned why: he has autism spectrum disorder (ASD).

Despite speech-language therapy and other interventions, Ryan’s speech did not catch up to his twin’s. Now age 10, he has little functional speech, like an estimated 25 percent to 35 percent of people who have autism.1 “We know what his voice sounds like, but we don’t know what his talking sounds like,” Drebing says, a little wistfully.

Despite a surge in research and public interest in autism in recent decades, we still do not know why functional speech remains elusive for some people with autism. “Little is known about this group because they are rarely the focus of research,” according to a 2013 article by some of the top U.S. experts in autism.2

As a result, misperceptions may linger about these children and adults, about how much language they understand, how they learn, and the best ways to help them communicate. “When someone is nonverbal,” Drebing says, “people tend to think they’re lower-functioning than they actually are. We need more data on the true intellectual level of people who are nonverbal.”

Two autism experts agree. In an article, they noted, “we know almost nothing about minimally verbal older children.” They called upon their fellow researchers to begin learning more about those “who, for too long, have remained at the neglected end of the autism spectrum.”3

The Spectrum of Speech in Autism

Decades ago, many, if not most, people diagnosed with autism had little or no spoken language. At the turn of the 21st century, experts noted that up to one half of children and adults who have autism “do not use speech functionally.”4 But the percentage of verbal people with autism has grown, for several reasons. First, the borders of the autism diagnosis expanded to include people who have milder symptoms and no history of a speech delay. Also, early diagnosis and intervention became more common and effective.

Today autistic people are found along a wide spectrum, from those who speak fluently to those who do not speak at all. People with little speech may be described as minimally verbal, and those with no speech may be called nonverbal. Very young children may be described as preverbal.

Some researchers and doctors worry that these terms lack precise definitions and may mislead families.3 For instance, there is no consensus as to how many words a person needs to say to be considered verbal. But experts do agree that verbal people use combinations of words “spontaneously” and “regularly” to communicate with others.4

Speech-language therapists generally do not focus on how many words children use, but rather on how they use them, explains Kate Smidl, a speech-language pathologist at Kennedy Krieger Institute in Baltimore, Maryland. Can a child request something he wants, ask a question, or make a comment? “We’re really looking at how functional a child’s language is,” she says. A child who repeats sentences from a movie, out of context – an autism symptom called echolalia – may be considered to have little functional speech. So may a child who cannot form any words, she says.

No one knows exactly why some children do not learn to speak fluently despite receiving therapies and interventions. Helen Tager-Flusberg, Ph.D., an expert in this field, was among those who had issued the call for more research on those children. In an email interview, she said research is pointing at several possibilities.

Some children may have problems with auditory processing, the system by which their brains interpret the words that they hear. Others may struggle with the motor skills needed to form words. For example, speech apraxia affects people’s ability to plan and coordinate the mouth and tongue movements used to talk. “There are also differences in brain anatomy – particularly connectivity in the speech production network. Still, there is much that we don’t yet know as so little research has been done,” says Tager-Flusberg, professor of psychological and brain sciences at Boston University and director of the Center for Autism Research Excellence.

One “common assumption” is that all children who do not speak have lower intelligence scores, according to an article by Tager-Flusberg and Connie Kasari.3 However, they point out, that is not always true. For example, some of these children score well on nonverbal intelligence tests5 and can understand a lot of spoken language.6,7

Take Ryan, who demonstrates his understanding of words he does not say. When Drebing asked Ryan if he wanted to walk their dog, he responded by putting away his iPad and getting his shoes to go outside. His actions showed he understood the question – and communicated an enthusiastic “yes” even if he did not say the word.

“If You Want Something, Let me Know”

“Lisa” rested her head on a desk at the Kennedy Krieger Institute LEAP Program, a school for students with autism and behavioral challenges. It was Monday morning, and Lisa (not her real name) could not keep her eyes open. Stefanie Carberry, a speech-language pathologist, sat across from the teenager, holding two iPad tablets. One was loaded with TouchChat HD, a communication application for people who have trouble speaking, and the other had a video game involving bubbles.

“All right, we are going to do some bubble pop,” Carberry said cheerfully. Lisa lifted her head and distractingly touched the iPad screen just enough to elicit the “thwat thwat” noise of bubbles popping.

“What did you just play?” Carberry asked.

Lisa roused and reached for the iPad loaded with TouchChat. She scrolled through screens of small squares containing pictures and words. By pressing the squares in order, Lisa formed a simple sentence. She touched the “I play” square and a computer voice said “I play,” then she touched “bubbles,” and the computer voice said “bubbles.”

Lisa’s head sank to the desk. Carberry said, “If you want something, let me know. Otherwise we will keep working.”

That was Lisa’s cue. With one finger, she flipped through the iPad’s picture squares to select the ones she wanted spoken aloud: “I want to sit at my desk.” That sentence earned Lisa a few minutes of rest time.

As Carberry later explained, staff is preparing the older students for the work or day programs they will attend when they graduate. People who do not speak, like Lisa, will need ways to communicate that they want a break or need something.

The Need to Communicate

Experts agree that everyone needs a way to communicate – whether it is through spoken words, or augmentative and alternative communication, also called AAC. AAC is a broad category that includes sign language, gestures, pictures, written words, and electronic devices like the one Lisa used. The American Speech-Language-Hearing Association, which is made up of speech-language pathologists and audiologists, says everyone has a right to effective communication.8

A youngster’s first exposure to AAC is often in the form of a small laminated square, containing a simple drawing and word. “Young children often begin their AAC journey with low-technology devices, such as picture icons or topic boards,” explains Smidl, the speech-language pathologist. “Children start to learn that the pictures represent their belongings, toys, or food, and they can start requesting things, like cookies. A child learns to point to a picture of a cookie or exchange a picture of a cookie, and they then get an actual cookie. That teaches them the cause and effect of communication,” she says.

One such picture icon system is the Picture Exchange Communication System, which relies on behavioral principles. Other AAC options are more high-tech. Children and adults may use electronic speech-generating devices, or software applications designed for mobile devices. Speech-language therapists can help select a communication system that would work for a particular student.

In fact, discussion of AAC should be a part of the special education meetings for those students. U.S. law requires public schools to provide assistive technology devices and services, such as AAC, when they are included in a student’s special education program.9

Augmentative communication is sometimes confused with facilitated communication, or FC, because they may use similar devices. But the two are different. In augmentative communication, the person with a disability touches the device or types on a keyboard by himself. In FC, a facilitator touches the person – typically on the hand or arm – while he types, points to letters, or uses a communication device.

Several organizations say FC has not been proven to work. They include the American Psychological Association and the National Autism Center.10,11 According to the American Speech-Language-Hearing Association, “There is no scientific evidence of the validity of FC, and there is extensive scientific evidence—produced over several decades and across several countries—that messages are authored by the ‘facilitator’ rather than the person with a disability.”12

The Link between Communication and Behavior in ASD

Communication may be the key to preventing the challenging behaviors found in some youth who have autism. The “prevailing assumption”13 is that people who cannot communicate become frustrated, and frustration may trigger tantrums, hitting, self-injury, running away, and screaming.

A majority of the autistic children and teenagers admitted to psychiatric units at six hospitals also had few or no verbal skills, according to the Autism Inpatient Collection study.14 The inpatient study is a project of the Simons Foundation Autism Research Initiative, which also funds the SPARK autism study.

The autism inpatient study found the link between behavior and communication to be complicated. Its researchers found that the hospitalized patients who spoke fluently had more aggression and angry outbursts than patients with limited speech.13 But that does not mean that communication skills do not influence behavior. Perhaps, they wondered, having a way to communicate may improve behavior by making it easier to cope with daily problems.

The Challenges of Being Minimally Verbal with Autism

When you live in a world that revolves around language, having little of it can complicate almost everything, including what researchers know about you. Many autism studies exclude children who have limited language or severe developmental delays because the tests needed for the research usually require the child to understand a certain amount of language.3 To address this problem, four researchers rated a list of standard assessments that are used in autism research. They found that 18 assessments were “well-suited for use with minimally verbal children,” 25 could be used with caution, and six were “unlikely to yield meaningful results.”2

Researchers also have looked at some high-tech solutions to the problem of assessing language abilities and intelligence in minimally verbal people. These are in the early stages of use for autism.

Could measurements of brain waves or eye movements give us more information about a minimally verbal person? For example, eye tracking systems could measure how long a child looks at a picture on a computer screen. This could indicate the words he understands and those he doesn’t. Other possible solutions include measuring electrical activity in a child’s brain, from electrodes attached to her head, when looking at a computer screen and listening to words.3

In a 2013 article, Kasari and Tager-Flusberg called for research into why autism has a greater effect on the ability to speak than intellectual disability does, by itself. “For any given level of intellectual disability, the child with ASD is more likely to remain nonverbal,” they noted. They also recommended research into therapies that target speech and language. “To date, there is scant evidence for effective language interventions for these children.”

Six years later, other researchers reached a similar conclusion, after reviewing 29 studies about speech interventions for nonverbal and minimally verbal people on the spectrum. Research into the most effective interventions for them is lacking, they concluded.15

Tager-Flusberg says that the answers about why some people with autism do not speak will come from different areas of science. “The answers (and there are likely many factors) will come from many different disciplines, and it is important to bring into this area of ASD research people who have the expertise in other areas, such as speech science, auditory science, neuroscience, and genetics.”


This is an updated version of an article that appeared on in November 2018.


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