SCOTT SIMON, HOST:
We're reporting this week on the most common reading disability. Ask just about anyone what dyslexia is, you'll almost certainly hear something like this.
UNIDENTIFIED WOMAN #1: When they read, they get, like, B's and D's - like, they're switched around.
UNIDENTIFIED MAN #1: They can either appear out of order, sometimes backwards.
UNIDENTIFIED WOMAN #2: They write backwards.
UNIDENTIFIED MAN #2: Backwards order.
UNIDENTIFIED WOMAN #3: Mixing letters up.
UNIDENTIFIED WOMAN #4: All jumbled and everything.
SIMON: But experts say that's not really what dyslexia is all about. Gabrielle Emanuel of the NPR Ed team reports.
GABRIELLE EMANUEL, BYLINE: At a reading center in Washington, D.C., Thomas Lester, who's 9 and has dyslexia, is working with a tutor.
UNIDENTIFIED WOMAN #5: I want you to read down the list for me, OK, Thomas?
EMANUEL: One of the words is D-A-B. As soon as Thomas has read it, his tutor covers it with her finger.
THOMAS LESTER: Dad.
UNIDENTIFIED WOMAN #5: What letters are you picturing when you say dad?
UNIDENTIFIED WOMAN #5: D-A-D - let's see if it matches.
EMANUEL: Thomas didn't quite get it, so she lets him see the word again.
UNIDENTIFIED WOMAN #5: Good job. It is D-A-B.
UNIDENTIFIED WOMAN #5: Dab, good.
THOMAS: Dab (laughter).
EMANUEL: Thomas is a smart kid, but he's confused lowercase b and d. After all, they're both sticks with bubbles at the bottom. They're just mirror images of one another. Now, Thomas has dyslexia, and that confusion is what many people think dyslexia is all about. But Guinevere Eden, who directs the Center for the Study of Learning at Georgetown University, says this is actually something everyone does when learning to read.
GUINEVERE EDEN: The brain wasn't designed to read.
EMANUEL: People naturally pick up spoken language, but we have to train our brains to read.
GUINEVERE EDEN: Your brain will essentially take other brain areas that were designed to do something else and use it towards reading.
EMANUEL: One of those areas is in the visual cortex at the base of the brain kind of underneath our ears. For people who don't know how to read...
GUINEVERE EDEN: It helps us recognize objects and faces.
EMANUEL: And when you do learn how to read, this part of the visual cortex helps you recognize letters and words. But since the area's original purpose was to recognize objects, it's wired to recognize one object from many different angles.
GUINEVERE EDEN: When I see a chair from one angle and I see it from the other angle, I still know it's a chair. I just know that it's been rotated. But in reading, you have to overrule that system so that you know that B and D are two separate objects.
EMANUEL: Everyone has to train their brain to do this. That's why lots of little kids start off writing their threes and fours backwards and then stop. They've trained their brain. The reason you might see this confusion more in children with dyslexia is because they spend more time at that early stage of reading, not because this is the cause of their reading problems. As everyone learns to read, those B's and D's and P's and Q's sort themselves out. For people with dyslexia, it might just take a little bit longer. Gabrielle Emanuel, NPR News. Transcript provided by NPR, Copyright NPR.