Kids with dyslexia have trouble reading. They struggle to connect the letters they see to the sounds that are associated with those letters. But this doesn’t mean all kids struggle with reading in the same way.
Some kids find it hard to recognize words by sight. Reading too slowly can also be a big issue. These can both lead to poor reading comprehension. Many kids have difficulty in more than one area, and their reading challenges can also change over time.
Researchers have been trying to figure out what causes dyslexia. Is there one weakness—a single deficit—that causes all of these issues? Or do the various issues have separate causes?
There’s only one official type of dyslexia. But over the years scientists have explored the idea that there might be different subtypes of dyslexia. Some of these haven’t panned out. Some are still being debated. Here are two of the more widely mentioned subtypes that you might hear about.
This is pretty much what people are thinking of when they talk about kids with dyslexia. Phonological awareness is the big issue here. This includes trouble breaking words down into syllables and into smaller sound units called phonemes.
For example, if you say a word out loud to a child with weak phonemic skills, she can hear the word just fine and repeat it back to you. But she’ll have trouble telling you how to split it apart into the different sounds that make up this word.
Difficulties in this area can make it hard for readers to match phonemes with their written symbols (graphemes). This makes it hard to sound out or “decode” words.
One way children get tested for issues in these areas is by being asked to read fake words, like jeet. The idea is to show kids a word they’ve never come across before and see if they can sound it out.
You may hear some people talk about dysphonetic dyslexia. This term is sometimes used to describe children with difficulties in phonological processing.
You may also hear some people use the phrase double deficit. This refers to kids who struggle with phonological awareness and with something called rapid automatized naming.
This term describes the ability to quickly name several things in a row, such as numbers or colors. When shown a bunch of letters in a row, some kids with dyslexia can name each of them—but can’t name them quickly.
Some experts think slow naming speed reflects difficulties with phonological processing in reading. Others think it encompasses a different skill we use to read fluently. Overall processing speed may also play a role.
Some kids struggle with reading because they can’t recognize words by sight. This is an important skill for a couple reasons. One is that some words have tricky spellings. Words like weight and debt can’t be sounded out—readers need to memorize them.
The other reason has to do with reading fluency. To be able to read quickly and accurately, kids need to recognize many common words at a glance—without sounding them out.
For example, beginning readers will come across a word like and many times. Eventually they’ll get so familiar with it that they don’t need to sound it out anymore. They can recognize it almost like a picture. But most children with dyslexia have problems sounding out words. This makes it hard to build a sight word vocabulary.
Some researchers have suggested that there’s a subtype of dyslexia that makes it hard to remember what words look like. This subtype is sometimes referred to as surface dyslexia. You may also hear it called dyseidetic dyslexia.
The idea for surface dyslexia comes from adults who lost the ability to recognize sight words. And there is limited support for using this subtype to describe some children’s reading struggles. It’s pretty rare for a child to only have trouble with sight words but not with sounding words out.
Teachers have strategies to help kids work on decoding skills and build up a sight word vocabulary. But subtypes of dyslexia, like surface dyslexia and phonological dyslexia, typically won’t be discussed as part of your child’s treatment plan.
Other “Types” of Dyslexia
You may hear other terms that use the word dyslexia loosely or incorrectly. For example, directional dyslexia refers to trouble telling left from right. It’s sometimes called spatial dyslexia or geographic dyslexia. Most experts recognize this as a common problem for some people with dyslexia. But they don’t see it as a separate subtype.
Visual dyslexia can refer to a range of things. Sometimes it’s used to describe surface dyslexia.
You may also hear visual dyslexia used to suggest an unusual visual experience when looking at words. Some people claim that reading can be improved through eye exercises or tinted lenses. But the American Academy of Pediatrics is one of many groups that do not endorse vision therapy as a treatment for dyslexia. That’s because there isn’t enough evidence to back it up.
You may also hear people talk about math dyslexia. This is an inaccurate name for a brain-based math learning issue called dyscalculia. This is not a form of dyslexia, although it’s not unusual for kids to have both of these issues.
Research on what causes these kinds of learning issues is ongoing. But keep in mind that right now there’s only one official kind of dyslexia. It’s also important to remember that the best way to identify your child’s issues is by getting a comprehensive evaluation.