Featured Research

from universities, journals, and other organizations

Dyslexia Redefined: Researchers Open A New Direction For Research And Treatment

June 6, 2005
University Of Southern California
A new theory of dyslexia challenges previous hypotheses and hints at a general deficit in the dyslexic brain.

The dyslexic brain may have a general problem forming perceptual categories, including the templates for printed letters and speech sounds, say USC neuroscientists.

This is reflected in a reduced ability to filter out visual "noise" that can obscure a pattern, the researchers suggest.

Their novel hypothesis, published in the current issue of Nature Neuroscience, raises broader questions: Does the dyslexic brain's trouble with patterns and noise extend to other senses? Does poor filtering inhibit the formation of perceptual categories? Or is poor formation of categories the root cause of dyslexics' problem with noise?

Dyslexia is the most common and perhaps least understood reading disability. Affecting millions of Americans, it has a history of uncertain explanations.

An old, discredited, but persistent view is that dyslexics jumble their letters.

In the 1980s, the subtler "magnocellular hypothesis" gained favor with some scientists. Named for a type of neuron, the hypothesis held that dyslexics struggle to process rapid visual signals. Language comprehension also requires rapid processing ability.

The Nature Neuroscience study casts doubt on the magnocellular hypothesis. The lead author was Anne Sperling, a graduate of USC's neuroscience program whose Ph.D. thesis was based on the study.

The research team, which included Zhong-Lin Lu and Franklin Manis, professors of psychology in the USC College of Letters, Arts and Sciences, and Mark Seidenberg of the University of Wisconsin, Madison, asked dyslexic and non- dyslexic children to identify patterns presented with and without visual noise.

"The dyslexic children performed the same as the non-dyslexic children when there was no noise," Sperling and colleagues wrote.

With noise, the dyslexic children needed more brightness contrast to perform the same tasks as their non-dyslexic peers. This was true whether the patterns required fast or slow processing.

"The findings, and particularly the (slow processing) ones, are consistent with the hypothesis that rather than having an M- or rapid- processing deficit, dyslexic children have difficulty setting their signal filters to optimum and ignoring distracting noise," Lu stated.

"Kids with dyslexia ... have a hard time focusing in on what's relevant and ignoring what is irrelevant," Sperling said. The study offers guidance for parents and teachers. On a basic level, any method that helps children to concentrate on a reading task and excludes distractions should be helpful, Sperling said.

Specifically, programs that help children to form sharper perceptual categories for sounds and letters could supplement existing dyslexia interventions, said the authors, who questioned the cottage industry of visual tools that has sprung up around the magnocellular hypothesis and related theories.

"Our research provides an explanation for why the child is failing to read and helps to explain why certain methods are effective. It does not support the idea that children need special glasses or visual training or anything specifically related to treating their vision," Seidenberg wrote.

"We do not think this is a specifically visual problem," Seidenberg added. The research team plans to conduct an analogous study of hearing to check whether dyslexics also have trouble separating patterns of sounds from noise. Lu, Manis and Sperling also plan to explore the root cause of dyslexics' problem with noise. Last year, the researchers showed that poor readers also lag in categorical learning, defined in the paper as the ability to deduce rules for sorting geometrical shapes.

Research in Finland and the U.S. has shown that infants with dyslexic parents fare worse than other children in forming categories or templates for speech sounds, Manis said. A child with shaky templates might then be less tolerant of noise.

"Is the reason they have problems with noise because they don't have good categories?" Lu asked.

The National Institutes of Health define dyslexia in part as "a specific learning disability that is neurological in origin. It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities."


Funding for this research came from the National Institute of Child Health and Human Development and the National Institute of Mental Health.

Story Source:

The above story is based on materials provided by University Of Southern California. Note: Materials may be edited for content and length.

Cite This Page:

University Of Southern California. "Dyslexia Redefined: Researchers Open A New Direction For Research And Treatment." ScienceDaily. ScienceDaily, 6 June 2005. <www.sciencedaily.com/releases/2005/06/050605234247.htm>.
University Of Southern California. (2005, June 6). Dyslexia Redefined: Researchers Open A New Direction For Research And Treatment. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2005/06/050605234247.htm
University Of Southern California. "Dyslexia Redefined: Researchers Open A New Direction For Research And Treatment." ScienceDaily. www.sciencedaily.com/releases/2005/06/050605234247.htm (accessed October 23, 2014).

Share This

More Mind & Brain News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations

Featured Videos

from AP, Reuters, AFP, and other news services

Academic Scandal Shocks UNC

Academic Scandal Shocks UNC

AP (Oct. 23, 2014) A scandal involving bogus classes and inflated grades at the University of North Carolina was bigger than previously reported, a new investigation found. (Oct. 23) Video provided by AP
Powered by NewsLook.com
Working Mother Getaway: Beaches Turks & Caicos

Working Mother Getaway: Beaches Turks & Caicos

Working Mother (Oct. 22, 2014) Feast your eyes on this gorgeous family-friendly resort. Video provided by Working Mother
Powered by NewsLook.com
What Your Favorite Color Says About You

What Your Favorite Color Says About You

Buzz60 (Oct. 22, 2014) We all have one color we love to wear, and believe it or not, your color preference may reveal some of your character traits. In celebration of National Color Day, Krystin Goodwin (@kyrstingoodwin) highlights what your favorite colors may say about you. Video provided by Buzz60
Powered by NewsLook.com
First-Of-Its-Kind Treatment Gives Man Ability To Walk Again

First-Of-Its-Kind Treatment Gives Man Ability To Walk Again

Newsy (Oct. 21, 2014) A medical team has for the first time given a man the ability to walk again after transplanting cells from his brain onto his severed spinal cord. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.


Breaking News:

Strange & Offbeat Stories

Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News


Free Subscriptions

Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile

Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?

Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins