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Read My Eyes
February 06, 2001
A stimulus on the screen (a square or cross shape) is followed by a reward in the form of an animation on either the right or left side of the screen. Although difficult for the naked eye to discern, studies show that babies quickly learn where to look for the animation based on the shape that comes before it.
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courtesy University of Rochester
Although infants cant tell us what they want, scientists now say that one look in their eyes may be enough to get an idea what they have in mind. Researchers at the University of Rochesters Infant Lab found that those baby blues can reveal what babies know and how they learn. By using a new way of tracking babies eye movements, theyre discovering new clues about how they process information.
The eyes have it
"One of the difficulties of course with babies is that they dont speak yet at the age at which we would like to study them," says Dick Aslin, professor of brain and cognitive science at the University of Rochester, who is leading the research. "So, by using a measure like eye movements we can get a silent assessment of the knowledge they have about a particular topic."
Before now it wasnt possible to track infant eye movements because eye trackers used to be mounted on the head, making them too big and heavy for babies to wear. But remote eye tracking systems solve that problem. At the Rochester lab, researchers have the mother hold her baby on her lap in front of a TV screen and fit the infant with a knitted cap that has a small magnet inside. The magnet guides an infrared camera that tracks the childs eyes even when he or she wriggles around, as inevitably happens.
"This technology has really opened up the possibility of recording their eye movements continuously over a fairly long period of time, and therefore we can measure their learning," says Aslin.
Learning to look
Meanwhile, eye tracking research conducted on adults to see how they naturally process visual stimuli has yielded surprising results. Check out our special video section in cooperation with Popular Science Magazine.
To do that, researchers show the baby a stimulus on the screen, such as a square or cross shape. This is followed by a reward in the form of an animation on either the right or left side of the screen (depending on whether it was a cross or a square). Aslin and his team have found that babies quickly learn where to look for the movie based on the shapes category. "Whats really amazing is how quickly they can learn things in a matter of minutes in the laboratory setting," Aslin says. "I think thats the most surprising thing about this work."
But the experiment doesnt end there. Babies are given a brief rest and then asked to apply their new knowledge. When shown something theyve never seen beforea shape of a different colorthey usually look in the correct direction to see the movie. "They will generalize. That is, they will place that object in one of those two categories. And of course because we cant ask them questions, this eye movement technique has been revealing of their ability not only to form categories, but to learn new items that go into categories theyve just learned," explains Aslin.
Researchers found, however, that when they rotate what should be a familiar shape, babies become confused, suggesting that they have to learn to ignore certain features, in this case orientation, in order to be able to categorize objects.
Grad student Bob McMurray gives a quick post-experiment analysis of Meghans performance in the movie above.
File size is 924K—please be patient. Requires the free QuickTime Player. If you prefer to use RealPlayer, click here.
The team plans to expand its research by testing infants space perception, according to Bob McMurray, a graduate student who is working on the studies. After training babies to look in one direction after seeing their mothers face and another direction after seeing their fathers face, theyll start to hide certain facial features to see exactly what it is that babies pay attention to.
They also plan to study how babies perceive objects that are occluded by other objects. (When you look at an object, its often partially hidden by something. But you can still tell what it is by the part thats visible.) "If you think about it, virtually everything we see is occluded by something else. We never see an object in its entirety," says McMurray. "So a baby that cant fill in the missing parts of an object has a very different visual experience than a baby who can."
Additional experiments will include using sounds instead of shapes, in the hope of understanding how babies acquire language, according to Aslin.
The scientists are eager to share their technique with other labs. "We believe that techniques like this that have been established in normal babies can then be applied to various experiments that would have to do with assessing infants who might be suspected of having difficulties with learning," says Aslin.
Elsewhere on the Web
The Consortium for Research on Eye Tracking in Infants (U of Rochester)