Alexithymia, not autism, could drive eye-gaze patterns | Spectrum
Face to face: Autistic and non-autistic people may not differ much in how they look emotional information in the eye.
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Gaze patterns when looking at a face are more related to alexithymia, a condition characterized by difficulty recognizing one’s emotions, than to autism, according to a new study. The results suggest that some of the differences in emotion processing that are believed to be the core of autism are actually due to alexithymia, the researchers say.
Although it is often believed that autistic people have difficulty identifying and responding to facial expressions and emotions, research has been inconsistent.
But growing evidence suggests that these difficulties are actually due to high rates of alexithymia in autistic people, says lead researcher Geoff Bird, professor of cognitive neuroscience at Oxford University in the UK. About 50 percent of autistic people have alexithymia compared to 5 percent of non-autistic people.
“It is alexithymia, not autism, that drives these symptoms,” says Bird, “which is why the literature provides such a mix of results and such a wide variety of different skills in autistic individuals.”
Researchers measure emotion processing by tracking how often one person fixes their gaze on another person’s eyes, usually in series of still images. In the new study, the team observed how these gaze patterns changed under different circumstances and while participants watched videos to better approximate the natural interactions.
“When I try to make a coffee, I may look at items in the kitchen differently than when I wash them,” says study leader Hélio Clemente Cuve, a PhD student at Oxford University. “The way people look at faces and expressions depends a lot on what they do.”
Participants – 25 autistic and 45 non-autistic adults – watched short videos of people showing a neutral expression, which in most cases was followed by an expression of one of five emotions: happiness, sadness, anger, fear, or disgust. In some cases they tried to recognize the emotion or judge its intensity, and sometimes they were told beforehand what emotion they would see.
Each participant also completed surveys that measured characteristics of autism and alexithymia, as well as symptoms of depression and anxiety.
Under all test conditions, degrees of alexithymic traits more accurately predicted how much time a participant spent looking in the eyes and how that behavior changed over time than levels of autism traits, the researchers found. And people with more alexithymic traits looked less often in the eyes than people with fewer traits, especially when exploring faces freely.
“If we don’t investigate alexithymia, we are likely missing out on important aspects of social emotional behavior that we would not otherwise have,” says Cuve.
The results were published in Cognition in April.
People with and without autism adjusted the amount of time they spent looking in the eyes depending on what they were asked to do. For example, when they were advised to expect a particular emotion, their gaze patterns were more structured and predictable than when they were rated the emotion – suggesting that they seek less information from the eyes.
However, higher alexithymia decreased the extent to which a person modulated their gaze in response to instructions. And in people with alexithymia, cued gaze patterns became no less predictable.
The results contradict the theory that autism is driven in part by the inability to incorporate prior knowledge into decision-making, Bird says, because autistic people’s gaze patterns became more predictable when they knew the emotion they would see.
“I’m not sure yet if I would say that alexithymia was responsible for this lack of top-down integration or the failure to use that prior information – that would probably be going too far,” says Bird. “But the results are certainly not really compatible with this notion that people with autism do not use prior information in their judgment or behavior.”
The results are “very exciting, very impressive,” says Uttama Lahiri, associate professor of electrical engineering at the Indian Institute of Technology Gandhinagar in Gujarat, India. Analyzing momentary patterns in response to dynamic emotions rather than static images is particularly useful, says Lahiri, who is studying moment in order to develop virtual reality platforms for autistic children.
The paper provides strong evidence for Bird’s hypothesis that instantaneous patterns are driven by alexithymia rather than autism, says Jennifer Cook, senior fellow at the University of Birmingham, UK Trains.
“That’s crucial,” says Cook. “If you do a study that you didn’t control alexithymia and you claim that what you found is specific to autism, how do you know if you haven’t controlled it?”
For example, Cook found that autistic and non-autistic adults differ in their perception of anger, but not happiness or sadness, after controlling alexithymia, suggesting that autism affects the processing of some emotions but not others.
The methods used in the paper – specifically the level of predictability over time – also provide a roadmap for other researchers, Cook says.
“I can imagine that this will be used a lot in the future,” she says.