[♩INTRO].

You might know of dyslexia as a reading disorder, or that one condition that makes letters seem to “float around on the page.” And that's understandable, because it does mess with people's ability to read. But it's more complex than letters flipping around and floating away.

Years of research suggest that people with dyslexia might struggle with processing letters because they also have trouble processing… of all things… rhythm. People with dyslexia tend to read more slowly than others, misspell words, or confuse letters that look similar. And the disorder is far from being uncommon.

Most estimates say it affects at least one in ten people. But despite its impacts on reading, dyslexia may actually be caused, at least in part, by something more musical. Whether you realize it or not, language has a whole lot of rhythm. ♩ Whole lot of rhythm.

A whole lot of rhythm ♩ ♩ A whole lot of rhythm. A whole lot of rhythm ♩. Just like that.

And I'm not talking about, like, beatboxing or slam poetry… or whatever I just did. I'm talking about everyday speech. Think about it like this:.

If you say a word like “difficult,” there's a right way to stress and pitch those sounds. DIFF-icult is right, and diff-IC-ult just… sounds kind of weird. This rhythm that's built into language is known as prosody.

Most people have no trouble processing it—they do it without even thinking. But a study published in 2011 showed that people with dyslexia tend to have a harder time with this. They're much less able to tell if a mis-stressed word is pronounced right or wrong.

And if you have trouble parsing the rhythmic stress patterns in words, that can make it extra tricky to match letters to the sounds of words. In other words, if you don't have a good internal representation of what the word is supposed to sound like, when you read something, there are fewer clues to help you link letters on the page to the meaning of the word. Scientists believe this might happen because of differences in the way dyslexic brains sample sound.

According to the theory of temporal sampling, as sensory information, like speech, enters your brain, your brain takes snapshots of that information. So it doesn't just absorb information continuously; it takes a bunch of snapshots at different rates, some quicker than others. And it uses those snapshots to put together an image, or, in this case, an auditory representation, of the signals it's receiving.

If we stick with the camera metaphor for a sec, you can imagine the brain as a camera that's trying to take a picture of a hummingbird. A non-dyslexic brain is like a camera with a fast shutter speed:. It captures a clear moment in time, even though the hummingbird's wings are beating really quickly.

On the other hand, a dyslexic brain is more like a camera with a slower shutter speed so instead of capturing the wings clearly, it captures a blur. In the real world, what that means is that, sometimes, a dyslexic brain doesn't process rhythmic information as fast as it's arriving. As a result, someone with dyslexia may not lock into rhythms in language as well as someone without dyslexia.

The difference, or at least one of them, seems to be in a part of the brain called the arcuate fasciculus, which is a kind of connective highway between parts of the brain involved in language. In those with dyslexia, the arcuate fasciculus is smaller, with less white matter to carry

information. And the fewer connections, the harder it becomes to pass information around those language areas.

Along with its role in language, the arcuate fasciculus is also really important for music. In fact, there's some evidence that people with dyslexia could make use of this connection between language and music to improve their reading skills. A 2016 study used what's called cognitive-musical training, or CMT, on two groups of children between 8 and 12 years old. 12 children had dyslexia, and 22 had typical reading skills.

For 18 hours, either spread over three days or six weeks, these children practiced musical exercises, like tapping out rhythms, learning about pitch and duration, and playing simple melodies. Before and after their training, researchers tested their ability to tell apart similar sounds, such as “ba” and “pa,” as well as pick out examples of incorrect stress in three-syllable words. The results showed that following CMT training, the kids with dyslexia got significantly better at distinguishing sounds from one another, as well as picking up on incorrect prosody.

On top of that, a further study by those same authors found that following the six-week training, dyslexic kids' reading skills improved, even without any specific reading training. The idea of using this connection between music and language is really exciting. But the science isn't settled yet.

While studies like this one found strong effects on reading, others just haven't. So for the moment, psychologists need to better understand what exactly might be influencing improvements in reading, and whether or not other experiments can get the same results. Dyslexia is just one of the many variations in how our brains interpret the world around us.

But thanks to its complexity, it has a lot to show us about how we process things like language and rhythm and use them to make sense of our world. Thanks for watching this episode of SciShow Psych! And a special thank you to our patrons for supporting the work we do.

It takes a lot of people to make a SciShow video, and we couldn't do it without you. If you're interested in being part of our patron community, you can find out more at patreon.com/scishow. [♩OUTRO].