Dyslexia Roots Studied
September 21, 2012

Researchers Study Root Of Dyslexia

Connie K. Ho for redOrbit.com — Your Universe Online

Five percent. That´s the number of people who suffer from dyslexia worldwide, according to researchers at the College of Science at Northeastern University. Even with the number of people who suffer from the disorder, there still isn´t a clear reason as to what causes the disorder.

With this in mind, a collaborative study was completed by researchers from Harvard Medical School, Western Galilee College, McGill University and Northeastern University College of Science, which highlighted how dyslexia may be the result of impairment of a different linguistic system than previously understood.

To begin, dyslexia is considered a reading disorder and can influence how people respond to spoken language. Problems related to dyslexia can be seen early on, even before reading skills are acquired by infants. The findings were recently featured in the open access journal PLoS ONE.

"Our research demonstrates that a closer analysis of the language system can radically alter our understanding of the disorder, and ultimately, its treatment," commented Iris Berent, a researcher from Northeastern University, in a prepared statement.

The researchers explained how speech perception is thought to be a part of two different linguistic systems. One system is based off phonetics, allowing the individual to extract discrete sound units from an acoustic input. The other, a phonological system, joins the units together to create individual words. Based on past studies, researchers believed that dyslexia was due to a phonological impairment. However, the results from the new study show that the phonetic system may be the cause of dyslexia.

"Research has long recognized that reading and language are closely linked, but this recognition has had little impact on how dyslexia is studied. Our research demonstrates that a closer analysis of the language system can radically alter our understanding of the disorder, and ultimately, its treatment," the authors wrote in a statement.

The study featured a group of Hebrew-speaking college students who were able to track abstract phonological patterns, but had problems being able to tell the difference between similar speech sounds. The participants included both skilled and dyslexic readers who were given fake words in Hebrew, which was the language utilized in the study. Some of the dyslexic participants had difficulties telling the difference between the real and fake words. Another portion of the study showed that dyslexics couldn´t distinguish between digital sounds copying human speech and real human speech.

“Some researchers identify phonology as any process related to speech processing, whether it is speech perception, or the map ping of letters to speech sounds,” commented Berent in an article by News @ Northeastern. “I think the contribution of our work, is saying, ℠Look at the linguistics, look at what the two systems really are doing in human languages and maybe that will help you understand dyslexia.´”

The researchers believe the results of the study show that there were issues participants had with their phonetic system as opposed to the phonological system. The cause of the disorder could also be related to a lower-level part of speech perception, like the auditory system. Or it could be due to problems in early development of the human brain.

"Our findings confirm that dyslexia indeed compromises the language system, but the locus of the deficit is in the phonetic, not the phonological system, as had been previously assumed,” noted Berent in the statement.

Based on the findings, researchers are better able to understand the learning disorder but do not provide a specific solution for people with dyslexia.

“Our present demonstration that these two components can be dissociated underscores the urgent need for a more precise definition of the phonological- and phonetic-deficit hypotheses,” concluded the authors in the paper.