One of the central goals in autism research is to better meet the needs and experiences of individual children on the autism spectrum, even and especially children who may not be able to easily communicate those experiences. Researchers hope that doing so will provide an inroad into helping those children and also into understanding the condition as a whole.
That goal would initially appear to have very little to do with eye blinking. In fact, most people don’t even notice when they blink. But without noticing it, we spend nearly 45 minutes of each day blinking, with eyelids closed, not seeing the visual information in front of us.
Researchers at the Marcus Autism Center at Emory University, together with a graduate student in Psychology at Yale University, have discovered a new way to use this information to actually measure how engaged people are with what they’re watching. And they can even use this technique to learn from children who, like those with autism, have difficulties communicating their interests to others. The results are reported in the December 12th online Early Edition of the Proceedings of the National Academy of Sciences.
The new method relies on measuring the precise timing of when people blink, and when they don’t. The research reveals that people unconsciously inhibit their blinking at precise moments. Why would people blink at some moments but not at others?
“When we blink, we lose visual information,” says Sarah Shultz, a graduate student in the Psychology Department at Yale University. “Our eyelids close. We’re not conscious of the timing of our blinks, but they still impact the visual information we take in.”
Shultz and her colleagues at the Marcus Autism Center, Ami Klin and Warren Jones, work with children with autism, studying how these children look at the world and how they learn from the things they pay attention to. While measuring what 2-year-olds look at when watching videos of other children playing, Shultz made an interesting observation: she noticed that the children blinked less while the videos were playing than they did before or after the videos.
“That initial observation opened the whole thing. It made us wonder if we might see the same effect at a micro-scale: that is, not just for a whole video, but moment-to-moment, whether the rate of blinking might go down or up depending on whether viewers perceived a scene to be more or less important,” says Jones.
The researchers tested the hypothesis by letting 93 two-year-old children watch a video. The video showed a simple scene of a boy and girl playing together. About half the children watching had Autism Spectrum Disorders. The researchers measured when children blinked and when they didn’t, and the results were surprising.
“Typically-developing 2-year-olds inhibited their blinking at the same moments in the video. And they were more likely to inhibit their blinking when watching more emotional moments, and when looking at the faces of onscreen characters,” said Shultz. Toddlers with autism, however, were more likely to inhibit their blinking when looking at physical objects, and at physical objects in motion.
The results show for the first time that eye-blinks are inhibited at precise moments so as to minimize the loss of visual information that occurs as the eyelids close during a blink. Importantly, exactly when that inhibition occurs depends on how important the visual information is to a viewer. The more important the visual information is to a viewer, the more likely he or she will be to inhibit blinking. While the children in each group blinked at about the same overall rate, and blinked less during the video than before or after, the timing of blink inhibition varied between groups: typically-developing toddlers stopped blinking to watch emotional facial expressions and actions, while toddlers with ASD stopped blinking when watching objects move. Each group of toddlers inhibited their blinking, but did so during moments that they perceived to be particularly important to process (and they actually increased their blinking during moments perceived to be less important).
Toddlers with autism also inhibited their blinking after actions happened, whereas typically-developing toddlers inhibited their blinking early. This suggests that typically-developing toddlers were anticipating the unfolding of the social interactions they watched, while toddlers with ASD were reacting, after the fact, to physical actions that had already happened.
“While we knew about young children with autism paying less attention to social cues and information, this is a new insight into understanding what kids engage with and what they perceive to be most important,” said Jones. “Even if they’re looking at the same thing, different children may perceive it differently. For a two-year-old with language delays, or even an 8 or 10-year-old who struggles to communicate, this kind of measure can tell us about that child’s experience and, with that information, hopefully improve our efforts to help that child learn.”
In addition to allowing unique insights into how children with Autism Spectrum Disorders engage with and experience the visual world, Shultz says that the finding is of broad relevance to understanding perception in general. “It’s remarkable that eye-blinks, a seemingly simple physiological function, should be inherently linked to something as complex as the subjective assessment of what content in the visual world is or is not engaging. This means that we can measure not only what a person is looking at, but also how important and engaging that thing is to a person,” says Shultz.
This method is now being applied to investigate the experiences of other children with ASD. When children with ASD look at different kinds of visual information, or at faces and eyes and information that might be useful when trying to understand other people’s actions, are children with ASD actually engaged with those stimuli to the same extent as their typical peers? Do children with ASD perceive those stimuli and their adaptive value in the same way? Because engagement with socially relevant stimuli may be critical for other aspects of neural and behavioral development – such as the acquisition of speech and language skills, and the specialization of brain function – this is a critical question. And the timing of when children blink may hold new answers.
The eyes are a window to the soul, but now it seems that the way that window opens and closes offers a deeper look inside.
Shultz, Klin, & Jones. (In Press). Inhibition of eye blinking reveals subjective perceptions of stimulus salience. Proceedings of the National Academy of Sciences.
The study was funded by the National Institute of Mental Health and the Simons Foundation.
Sarah Shultz is a graduate student in the Department of Psychology at Yale University. Ami Klin, PhD, is the Director of the Marcus Autism Center, Children’s Healthcare of Atlanta, and Chief of the Division of Autism & Related Disorders at the Department of Pediatrics at Emory University School of Medicine. Warren Jones, PhD, is the Director of Research at the Marcus Autism Center and Assistant Professor in the Department of Pediatrics at Emory University School of Medicine.
The Marcus Autism Center, in Atlanta, Georgia, is the largest center for clinical care of children & adolescents with Autism Spectrum Disorders in the country, providing comprehensive diagnostic and needs-based evaluations, and a wide array of treatments programs spanning severe behavior, language and communication, school-based and in-home programs, and feeding disorders. From 1991, Marcus has served more than 40,000 individuals and their families. For more information, visit www.marcus.org.