Dyslexia is typically seen as a reading disorder, but many dyslexics are also known to have trouble processing sensory information. Research now reveals that dyslexics find it especially difficult to shift their attention between visual and audio stimuli. This suggests that brain training with action video games could actually improve dyslexics' literacy skills.
Dyslexia isn't just a single, narrowly defined disorder — there are various types and symptoms of dyslexia. For example, some people with dyslexia have audio or visual deficits. And sometimes, those deficits stand apart from comprehending letters, words and their related sounds, explained Vanessa Harrar, a psychologist who studies multisensory integration at the University of Oxford in the U.K.
What this often means is that these people will take longer to process or understand visual or audio stimuli. Over a decade ago, researchers suggested that the root of these problems has to do with attention. "In general, dyslexics have a kind of shifting delay when they turn their attention from one stimulus to another," Harrar told io9. This is called "sluggish attentional shifting."
Knowing that dyslexics have these attention-related, sensory deficits, Harrar and her colleagues initially wanted to come up with a kind of test to "capture all of the dyslexics." "[The disorder] presents itself as so many different symptoms," Harrar said. "We were looking for some kind of multisensory test that would make it easier to know who is dyslexic." The team decided to focus on reaction time tasks.
The researchers sat dyslexics and non-dyslexics in front of a computer, and then presented them with different stimuli. Whenever the participants heard a sound, saw a flash or experienced both cues together coming from the computer, they had to press a button as quickly as possible. The team recorded and analyzed the participants' speeds for numerous trials.
The participants' performance on the individual tests were more or less what was expected, but the real surprise came when the researchers compared the reaction times across trials. "The differences we found [between dyslexics and non-dyslexics] involved switches between modalities," Harrar said, referring to the cases where the participants faced one type of sensory trial followed by a different type. "Our main finding is that is more difficult for dyslexics to go from visual to audio stimuli."
Specifically, the dyslexics' reaction times were, on average, 18 milliseconds slower when a visual trial was preceded by an auditory or multisensory trial than when a visual trial was preceded by another visual trial. But it was 35 milliseconds slower when an auditory trial was preceded by a visual trial than when an auditory trial was preceded by another auditory trial.
That is, the dyslexics showed sluggish attentional shifting, but only when turning their attention from their sense of sight to their sense of hearing. This suggests that dyslexics could learn "audio-visual phonological associations" faster if they hear how something is pronounced before seeing the corresponding letter or word.
The results of the research differ from previous, similar studies, but Harrar stressed that those studies didn't control for an additional, important variable: Localization. In Harrar's work, the flash of light and the sound both came from the direction of the computer screen. But in previous studies, researchers had the participants wear headsets, so the sound came from a different area (their head) than the flash of light. "They were not only switching senses, but also location," Harrar said.
The new study suggests that dyslexics are more focused on vision, and it is more difficult for them to shift their attention away from a visual stimulus — a finding that actually fits in with what scientists know about the attention aspect of dyslexia, Harrar said. When you read a line of text, your eyes move after your attention does. "You sort of shoot a spotlight to the next word, and then your eyes move," she said. "With dyslexics, their spotlight doesn't move, or it doesn't move as quickly or as far."
The idea, then, is that if you can train or improve their attention system, then everything else will follow. And, in fact, this is exactly what recent research has found.
Last year, scientists reported that playing action video games helps dyslexic children read better. These games have a lot going on, requiring you to react quickly to the demands of the game. "It trains them to move their eyes and shift their attention quickly, so the basic attention deficits naturally fix themselves," Harrar said. "Then when it comes to reading, suddenly they are reading much faster."
Harrar and her colleagues believe that it's possible to make action video games even better for some dyslexics. Instead of having the game loaded with constant multisensory stimuli, you could design a game that purposefully switches back and forth between visual and audio stimuli. This will, presumably, help dyslexics train their ability to switch from one sense to another.
The researchers now want to repeat their work, but keep a keen eye on the type of deficits the dyslexic participants have. In their study, they didn't look to see if their participants had mainly auditory or visual deficits. It may be the case that their sample was made up of dyslexics with mostly visual deficients, and that dyslexics with auditory deficits actually have more trouble switching from sounds to sights.
Check out the study over in the journal Current Biology.
Top image from Assassin's Creed 4. Inset image via Léa Gagnon; Micheline Gloin; Daphneé Harrar.