Study of eye-tracking of children looks at how they learn to see the world

From The NY Times:

The infants and toddlers resemble cyborgs as they waddle and crawl around the playroom with backpacks carrying wireless transmitters and cameras strapped to their heads. Each has one camera aimed at the right eye and another at the field of view, and both send video to monitors nearby. When the video feeds are combined, the result is a recording in which red cross hairs mark the target of a child’s gaze.

Scientists are using the eye-tracking setup to learn how children look at the world as they figure out how to interact with it. In the lab, children 5 months and older crawl and walk up, down and over an obstacle course of adjustable wooden slopes, cliffs, gaps and steps. And to add to the challenge, the subjects are sometimes outfitted with Teflon-coated shoes or lead-weighted vests.

It may seem like the set for a new reality television show, but there are no prizes, except perhaps for the researchers. They hope to understand what prompts one child to respond to another, how infants coordinate their gaze with their hands and feet to navigate around obstructions or handle objects, and how these very young children adapt to changes, like those brought on by slippery footwear.

The findings provided by these eye-trackers so far (the first light enough for children to wear) suggest that infants may be more capable of understanding and acting on what they see than had been thought. “Quick gazes at obstacles in front of them or at their mothers’ faces may be all they need to get the information they want. They seem to be surprisingly efficient,” said John Franchak, a doctoral candidate in developmental psychology at New York University.

Although vision might largely seem effortless to us, in reality we actively choose what we look at, making about two to four eye movements every second for some 150,000 motions daily, said Karen Adolph, also a developmental psychologist at N.Y.U. “Vision is not passive,” she said. “We actively coordinate our eye movements with the motions of our hands and bodies.”

Eye-tracking studies have existed for more than a century, but the instruments involved were typically desk machines. The wearable eye-trackers that Dr. Adolph, Mr. Franchak and their colleagues use are based on devices developed over the last decade by Positive Science, a New York company, with money from the United States Naval Research Laboratory. They were designed to help scientists discover things like how combatants spot camouflaged targets in the field. Eye-trackers are currently being used in studies to learn the differences in how amateur and professional geologists scan landscapes and how people examine signs when looking for exits during emergencies.

To adapt the eye-trackers for children, whose noses and ears are too small for the eyeglass-mounted versions employed with adults, the founder of Positive Science, Jason Babcock, used padded headbands, spandex caps and Velcro tabs to keep the cameras in place. The headgear weighs just 1.6 ounces, about as much as a pocketful of change. Since infants often fall headfirst, spotters hold straps attached to vests the children wear to prevent them from injuring themselves with the cameras, but the children are otherwise free to move.

The scientists recruit parents and children for their work from maternity wards. Although a few toddlers could not be coaxed into donning the eye-trackers, so far the researchers have tested about 70 children with the devices.

“The beauty of this is how it helps capture what infants are thinking about during natural behavior. Since what they are looking at is related to their ongoing actions, tracking eye movements allows a pretty direct readout of what might be going on in their heads,” said Mary Hayhoe, a perceptual psychologist at the University of Texas at Austin, who did not take part in the research.

In studies of six 14-month-olds allowed to roam a playroom in Dr. Adolph’s lab cluttered with colorful balls, plush dolls and toy cars, the researchers found that in roughly a quarter of all encounters with obstacles, the infants could navigate past without centering their gaze on them. “Adults only fixate on obstacles about a third of the time, and 4- to 8-year-old children fixate on obstacles about 60 percent of the time, but it’s remarkable that infants can even navigate without looking,” Mr. Franchak said.

The researchers also found that during the studies infants looked at their mothers just 16 percent of the time. That is surprisingly low, Dr. Adolph said, given the importance a large body of past research has placed on children watching the faces of adults as they name objects to learn languages.

“These findings suggest children may not have to look very long to get the information they need, either from people or objects,” said Jeffrey Lockman, a developmental psychologist at Tulane University, who did not participate in the studies. “This gives new insights into how much information they need, or how quickly children might process this information.”

These preliminary experiments only scratch the surface of what scientists might find out about children with the eye-trackers. For instance, Dr. Hayhoe said, learning at what age infants start to look at the ground when someone drops a ball could shed light on when children are able to predict the likely consequences of actions, an important step in cognitive development.

Studies on what visual cues draw the attention of children with autism or on how children with motor disabilities interact with the world could be useful in tracking their progress or developing therapeutic interventions, Dr. Lockman said.

“This is a whole new way of asking questions that’s limited only by your imagination,” Dr. Adolph said.