For many years, researchers believed that dyslexia was caused mainly by difficulties processing speech sounds. However, a study from Carnegie Mellon University suggests that the picture may be more complex.
Researchers Lori Holt and Yafit Gabay investigated procedural learning—the type of learning we use to develop skills and habits such as riding a bicycle, tying shoelaces or driving a car.
Their findings, published in the journal Cortex, showed for the first time that people with dyslexia have difficulty learning complex auditory categories through procedural learning. This suggests that problems processing speech sounds may be a consequence of broader learning difficulties rather than the original cause of dyslexia.
Testing procedural learning
To investigate this, adults with dyslexia and adults without dyslexia played a specially designed video game.
Players navigated through a three-dimensional outer-space environment where they encountered different alien characters. Each type of alien was linked to a unique category of unfamiliar, computer-generated “warble” sounds. As the game became faster, players increasingly had to rely on the sounds, rather than the aliens’ appearance, to succeed.
What did the researchers find?
Participants with dyslexia were significantly less successful at learning the different sound categories. They also found it more difficult to apply what they had learned when new sounds were introduced later.
According to the researchers, this suggests that procedural learning difficulties may make it harder to learn and categorise speech sounds during reading development.
Why does this matter?
These findings are important because they offer a different way of thinking about dyslexia.
Rather than viewing speech-processing difficulties as the sole cause of dyslexia, the study suggests they may reflect a broader difficulty with procedural learning. This could help explain why some individuals with dyslexia also experience challenges that are not directly related to language.
The researchers believe that a better understanding of procedural learning could lead to more effective, evidence-based interventions in the future.
