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Does a Baby’s Gaze Hold a Clue to Autism?

A photo of a mother pointing and a toddler following her gaze

Marina Sarris

Date Published: May 8, 2024

Can you tell if babies will develop autism by analyzing what they look at?

That is a question that neuroscientist Karen Pierce sought to answer when she began researching autism 20 years ago.

She knew that many older autistic children show unusual patterns of attention to faces and voices. They also may not shift their attention between people in the same way that other children do.

What if she could measure what babies pay attention to, and how they do it, to help diagnose autism before the signs become obvious? Could that lead to new interventions that take place early enough to affect the way their brains develop?

She found an answer in eye tracking technology, which enables researchers to measure how long toddlers pay attention to different types of scenes in a video that they watch.

Pierce and her research team have developed six eye tracking tests at University of California San Diego (UCSD), an Autism Center of Excellence and a clinical site of the SPARK autism study. Simply put, these tests measure whether a baby spends more time looking at people or objects. That’s important because, as her team has found, “what a child pays attention to plays a pivotal role in shaping brain development.”1

Pierce is among several researchers who are developing more objective ways to detect autism before the signs, such as communication and social delays and repetitive behaviors, become noticeable. They are using eye tracking tests and Magnetic Resonance Imaging (MRI) brain scans, or both, in their research.

Some of these researchers focus on the baby brothers and sisters of autistic children, who have a higher chance of having autism. Pierce’s studies are different in that they mostly include infants with no family history of autism.

Moving Objects and Dancing Children

During one eye tracking test developed by Pierce and her team, babies and toddlers look at a screen that shows moving geometric shapes on one side, and children dancing on the other side. The test measures exactly how long a child pays attention to the shapes and the children during the brief video.1,2

Another of her eye tracking tests pairs both sound and pictures. It measures whether the child prefers watching a short video of cars honking on a highway or a video of a woman speaking in the singsong “baby talk” voice that parents use with infants.3

Children who don’t have autism prefer the videos of people moving and talking over videos of geometric shapes and honking cars.

But many autistic children find the cars and shapes more interesting, to varying degrees, says Pierce, a UCSD professor who has a Ph.D. in experimental psychology.

Another eye tracking test measures a common challenge in autism, something psychologists called joint attention. Joint attention occurs when people share experiences with each other. For example, a mother sees a bird, points to it, and says “look at the bird” to her baby. The baby looks at the bird and then looks at her mother. But children on the autism spectrum are less likely to do this. They often do not look when a parent points at something, and do not point to things they want their parents to see.

“We don’t really know what babies are thinking and perceiving, but what we do know is that eye tracking is a very powerful tool that tells us what they want to pay attention to,” Pierce says. “And early brain development occurs based on their experience. If they are paying attention to social images and social sounds, they are going to develop that part of their brain and have faster development of language and social behavior.”

But babies who are more interested in geometric shapes or beeping cars may have slower development of the brain structures used during speech and social interactions, she says.

That is where intervention comes in.

Get SET Early: Screen, Evaluate, and Treat Autism

Pierce worked with San Diego pediatricians to develop a program called Get SET Early to screen, evaluate, and treat autism earlier than usual.4

The doctors screened babies for developmental delays at well-child visits at 12, 18, and 24 months. They could refer any child with delays for testing at UCSD. At UCSD, toddlers receive eye tracking tests, an evaluation by a psychologist, and a brain MRI while they sleep. Children with any delay are referred to state early intervention services on the same day as their UCSD testing.

Children who are referred to UCSD at 12 months and diagnosed with autism may begin autism therapies as early as 15 months, Pierce says. That is much earlier than usual.

Among children in SPARK, the largest study of autism, the average age of diagnosis is 4 years old.

Early intervention could change the course of a child’s autism, Pierce says. The younger the child, the more able their brain is to form new connections and pathways, she says. “There are a few compelling studies showing that intervention that is started before 18 months actually has more effectiveness than intervention started after that time. These findings come from research both within the field of autism as well as outside the field of autism,” she says.

“He’s a Boy. He’ll Grow Out of It.”

Emily Ransom, a parent in the SPARK autism study, welcomes efforts to make getting a diagnosis and services easier and faster.

Ransom noticed her son’s developmental delays before his first birthday. Those differences became more obvious when he did not start talking on time. But his doctor did not share her concerns.

“His pediatrician kept telling me, “Oh, he’s a boy. He’ll grow out of it. And I’m saying, ‘He’s still not talking, and he should be talking by now.'”

She took the initiative to have her son evaluated. He was diagnosed with autism at age 2. Her community in Indiana did not have enough therapy providers, so she had to contend with wait lists for behavior and other therapies during his preschool years.

Ransom has a 3-year-old daughter who also has autism, although the girl’s traits differ from her older brother’s. Her daughter talks, and her son is non-speaking.

Autism occurs along a wide spectrum of social and communication abilities, even among siblings like Ransom’s children.

Capturing Different Types of Autism

Eye tracking is a powerful tool because it can identify different types of autism, Pierce says.

For example, about 30 percent of autistic children scored the same as typically developing children on the eye tracking test involving geometric shapes and social situations, Pierce says. Those children were more likely to have better language and social skills, and fewer autistic traits, when they are a few years older, she says.

On the other end of the spectrum, 20 percent of the children preferred looking at geometric shapes most of the time. They had lower language abilities and more significant autism traits when they got older. The rest of the autistic children fell somewhere between those two extremes on that eye tracking test.5

In a new study, Pierce’s team combined eye tracking and other tests with data from brain scans. The researchers used MRI to record the way children’s brains responded to different types of speech. They found that children with the strongest interest in, and response to, baby talk speech also had stronger language and social skills.6

How Can Families Get Early Evaluations and Therapies?

Pierce and her team have expanded the Get SET Early program to include Phoenix, Arizona. In communities that do not have programs or providers who diagnose and treat autism in 1-year-olds, families can contact their state’s early intervention program for infants and toddlers for help.

These programs will test youngsters for developmental delays and provide general therapies and special education services.

“Early intervention programs are providing speech therapy, physical therapy, and occupational therapy. All of those things are helpful for young children with autism because they often have speech, motor, and sensory issues,” Pierce says.

Learn more about Pierce’s research by watching her webinar for SPARK, “Eyes Wide Open: Harnessing Eye Tracking for Advancements in Autism Diagnosis, Prognosis, and Treatment Progress.

Interested in joining SPARK? Here’s what you should know.

Photo credit: iStock


  1. Bacon E.C. et al. Autism 24, 658-669 (2020) PubMed
  2. Pierce K. et al. Biol. Psychiatry 79, 657-66 (2016) PubMed
  3. Pierce K. et al. JAMA Netw. Open 6, e2255125 (2023) PubMed
  4. Pierce K. et al. J. Pediatr. 159, 458-465.e6 (2011) PubMed
  5. Wen T.H. et al. Sci. Rep. 12, 4253 (2022) PubMed
  6. Xiao Y. et al. Nat. Hum. Behav. 6, 443-454 (2022) PubMed