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Planet Earth

Uncoordinated Eyeballs Keep Kids from Reading like Adults

InkfishBy Elizabeth PrestonJuly 24, 2013 1:22 AM


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Before new readers can move from Dr. Seuss to Doctor Zhivago, it's not only their vocabulary and appreciation of the Russian aesthetic that have to mature. Young eyes just don't move across words as easily as older eyes do. Like Thing One and Thing Two, the eyes bounce around independently and cause disorder.


The difference is in saccades, the little horizontal or vertical hops that ratchet our eyes through sentences. French researchers Magali Seassau of e(ye)BRAIN and Maria-Pia Bucci of Hôpital Robert Debré have been studying how this system develops in kids, including those with dyslexia.

For their latest study, the authors gathered 69 kids ages 6 to 15, as well as 10 adults. While using an eye-tracking device, the subjects silently read a paragraph of text from an age-targeted book. (Experimenters asked questions afterward to make sure the kids had actually read it.) In a separate task, subjects were given the same paragraph—except that all the vowels had been replaced by consonants. They had to skim the text and count the number of r's.


Seassau and Bucci saw evidence of several ways in which a person's reading machinery gets more efficient with age. As subjects got older, they made fewer saccades: their eyes took bigger, smoother jumps forward through the text, and fewer backward jumps. They also paused for less time in between leaps.


These findings fit with what the researchers had seen in earlier studies of reading. "The process becomes automatic" as kids age, Seassau says. "Reading gets to be faster, better and easier."

Younger kids are also worse than older kids or adults at keeping their two eyes coordinated with each other. This means saccades happen unevenly. In kids, "Eyes aren't coordinated when they jump forward on the letter or on the word," Seassau explains. Like competitors in a three-legged race, the eyes have to learn how to match their stride if they want to reach the finish line quickly.

Whether subjects were reading words or searching nonsense text for a certain letter, they got faster with age. Yet there were revealing differences in how their eyes and brains handled the two tasks.

Adults were faster and more accurate at reading than at searching. In the search task, their eyes worked inefficiently, making more saccades. The same thing was true of kids 10 and older. But kids ages 6 to 9 made the same number of jumps whether they were reading real words or hunting for letters in the nonsense paragraph. Younger kids read more like it's a scavenger hunt; older kids and adults read like they're running on a track. The results are in PLOS ONE.

None of the kids or adults in this study had unusual reading difficulties, but Seassau and Bucci are planning to expand their current research to kids with dyslexia in different countries. Earlier eye-tracking studies have hinted that dyslexic kids move their eyes through text in an immature, uncoordinated way. Learning more about how they read may help get everyone's eyes acting their age.

Images: Peter Rohleder (via Flickr); Seassau and Bucci.

Magali Seassau, & Maria-Pia Bucci (2013). Reading and Visual Search: A Developmental Study in Normal Children PLOS ONE DOI: 10.1371/journal.pone.0070261

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