Scientists find clues in your facial expressions that could be a hidden sign of autism

A person's facial reactions may reveal if they have autism, as scientists have found that those with the condition 'speak a different language' with their expressions. 

Researchers in the UK compared how autistic and non-autistic people expressed various emotions and discovered noticeable differences in how anger, happiness, and sadness were shown in the faces of those with autism.

When showing anger, those with autism tended to move their mouths more and their eyebrows less than their peers.

Autistic smiles were less exaggerated when showing happiness. They didn't move their eyes as much, and their cheeks didn't raise, making the smile look like it didn't fully reach the upper half of their faces.

When expressing sadness, autistic participants raised their upper lip more to create a downturned mouth, which was significantly different from those without the condition.

The team from the University of Birmingham suggested that these differences could explain why people with autism struggle to recognize the emotional reactions of others, and vice versa.

Autism spectrum disorder is a condition that affects how a person communicates, interacts, and experiences the world, typically appearing in early childhood.

Common signs include having difficulty interacting with others socially, struggling with speech, and developing various sensory sensitivities, such as being overwhelmed by loud noises or textures.

Autism has been called a 'spectrum' disorder because the symptoms can vary widely in type and severity.

In the new study, published in Autism Research, it was found that autistic facial expressions were more unique and varied from person to person compared to those of the other participants.

A condition called alexithymia, meaning someone has trouble identifying their own emotions, was found to be more common among those with autism.

Researchers explained that this made angry and happy expressions harder to tell apart; however, autism itself was not the direct cause of alexithymia cases.

For those without autism, making precise and consistent facial expressions while speaking helped them recognize emotions better in others.

However, autistic participants appeared to rely more on their general intelligence (IQ) to recognize facial expressions since their own reactions were a 'mismatch' for everyone else in the study.

One specific test designed to evaluate IQ revealed evidence that autistic participants had a strong ability to recognize emotions in computer-generated images mimicking smiles and frowns, but still struggled with their own facial expressions and those of other real people. 

Study author Dr Connor Keating, now at the University of Oxford, said in a statement: 'Our findings suggest autistic and non-autistic people differ not only in the appearance of facial expressions, but also in how smoothly these expressions are formed.'

Professor Jennifer Cook, the senior author of the paper, added: 'What has sometimes been interpreted as difficulties for autistic people might instead reflect a two-way challenge in understanding each other's expressions.'

The study included 25 autistic adults and 26 non-autistic adults, who were similar in age, gender, and IQ scores to create an even comparison. All of the participants with autism had previously received an official diagnosis.

Each person filled out online surveys to measure autism traits, alexithymia, and their ability to recognize emotions in faces.

For the emotional recognition part of the study, they watched simple dot-based animations of faces and rated how angry, happy, or sad the computer-generated images looked.

In a lab, participants made about 5,000 facial expressions, posing as angry, happy, or sad in two distinct ways.

The participants were either 'cued,' meaning they just made the face in response to a command, or they made a 'spoken' reaction, making an emotional face while saying a neutral sentence such as 'I saw a movie last night.'

Special cameras and software tracked tiny movements on their faces, recording things like how much their eyes, mouth, and eyebrows moved and how smooth their facial changes were.

Keating and Cook noted that their research only studied posed expressions, which could differ from natural, spontaneous responses that happen in real life. Posed faces might exaggerate emotions and widen the difference between autistic and non-autistic individuals.

They also didn't check how these expression differences directly affected how others perceived them during real person-to-person interactions.

Approximately one in 31 children in the US, more than three percent, have been diagnosed with ASD, according to the CDC's latest review in 2025.

A recent study also determined that autistic individuals were more likely to have a distinct walking style, commonly referred to as a 'duck butt.'

According to observations of young children with autism spectrum disorder, they often exhibited a more forward-tilted pelvis while walking, about five degrees more on average, compared to children without the condition.