Researchers at Marcus Autism Center, Emory University, and Yale University have discovered a new way to measure how engaged people are with what they're watching. The new method relies on measuring the precise timing of when people blink, and when they don't. More importantly, they can use this new method to learn how children with autism engage in the world around them. The results are reported in the December 12, 2011 online early edition of the Proceedings of the National Academy of Sciences.

If you are like most people, you probably don't notice when you blink. In fact, if you're an average adult, you probably don't notice that you spend nearly 45 minutes each day with your eyes closed - blinking. The research reveals that people unconsciously inhibit 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 Ami Klin and Warren Jones at the Marcus Autism Center and Emory School of Medicine 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 really started the whole study. 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 Warren 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, but some of the children watching the scene were typically-developing, while some had Autism Spectrum Disorders. The researchers measured when the children blinked and when they didn't, and the results were surprising.

"Typical 2-year-olds all 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. However, toddlers with autism were more likely to inhibit their blinking when looking at physical objects, and at physical objects in motion.

"While we knew that young children with autism paid less attention to social cues and information, this is a new insight into understanding what kids perceive to be most important," said Jones. "Even if they're looking at the same thing, typically developing children and children with autism may perceive a scene 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 human perception in general. "It is 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 how engaging that thing is to the person," says Shultz.