EXTRA LARGE LETTER SPACING IMPROVES READING IN DYSLEXIA. OR DOES IT?

http://www.understandingminds.com.au/blog/extra_letter_spacing_dyslexia/  - understanding minds

EXTRA LARGE LETTER SPACING IMPROVES READING IN DYSLEXIA. OR DOES IT?

June 12th, 2012

High prevalence, high impact disorders like dyslexia are prone to sensational claims from quacks, scientists, journal editors and journalists. The latest is a sensational claim from an article in the high-profile journal Proceedings of the National Academy of Sciences (PNAS) that increasing letter spacing “ameliorated the reading performance of dyslexic children” (Zorzi et al., 2012).

The popular media has picked up these claims. For example the ABC quoted the lead author Marco Zorzi as saying: “Our findings offer a practical way to ameliorate dyslexics’ reading achievement without any training”. But are the claims fact or fiction?

The idea for the study seems to have been grounded in effects of crowding in dyslexia (see Martelli et al., 2009). Crowding occurs when stimuli from the periphery interfere with processing of stimuli in the focus of vision. I am not an expert in this aspect of the dyslexia literature and perhaps someone else may comment. However, my non-expert eye suggests two problems with this literature. First almost all studies (see here for an exception) have used word and/or letter stimuli which confounds reading ability and ‘crowding’ effects. Second, most studies have used age-matched controls rather than reading-age matched controls which leaves open the possibility that the effects on crowding tasks are theconsequence of poor reading rather than the cause.

For the purposes of this post, let’s accept that crowding affects people with dyslexia more than good readers. Zorzi et al. (2012) predicted that widening the space between letters in words would decrease the effects of crowding and lead to better reading. They tested this idea in Italian and French people diagnosed with dyslexia (aged 8-14 years). The children had to read 24 short meaningful sentences taken from the Test for the Reception of Grammar. Print was Times New Roman 14-point. One reading condition had normal spacing between letters and the other had letter-spacing 2.5 points greater than normal (normal letter spacing is 2.7 pt in normal text; who knew?). Why they didn’t use single words and nonwords instead of the text-reading task is unclear given that dyslexia is widely acknowledged to be a deficit in single-word reading. People with dyslexia read better in context than they read words in lists (see here). Surely if crowding was the/a cause of dyslexia we would see it more in reading of word lists rather than stories and if increasing letter-spacing improved reading in dyslexia we would see larger effects in single word task?

Anyway….The results of one experiment showed that both the French and Italian groups with dyslexia made less reading errors in the condition in which letter-spacing was greater than normal. However, that on its own tells us nothing other than that doing something led to less errors. It doesn’t say that the specific manipulation (increased letter-spacing) was the key factor. It may be that chewing gum while reading does the same thing. Zorzi et al recognised this and suggested that if crowding really does affect reading and extra letter-spacing reduces crowding effects it is more important to show that people with dyslexia make less errors in the increased letter-spacing condition than reading-age matched controls. This they attempted to do in a second experiment.

The data from Experiment 2 (Zorzi et al) are shown in the figure below. Zorzi et al claimed that the increased letter-spacing condition improved the reading (i.e., they made fewer errors) of their French and Italian groups with dyslexia compared to the reading-age matched controls. These data are what the sensational claims reported in the media are based on. The problem is that their ‘control’ group were not of the same reading-age. Groups with the same reading ability should perform equally in the normal-spaced condition. The Figure below shows that this was not the case. The “reading-age matched controls” were significantly better readers in the first place.

What does this methodological flaw mean? Essentially it means that the claims Zorzi et al (or at least the media) made cannot be supported by the data. Using a group of younger children who were already better readers than the people with dyslexia is irrelevant to the research question. It leaves a data set that is subject to the same criticism as their first experiment. That is, it tells us nothing about the specific manipulation (increased letter-spacing) and it remains possible that any experimental manipulation, including the ridiculous like chewing gum, produces the same results.

Furthermore, it is possible, indeed likely in my view, that the reason the children in the “reading-age matched control” group did not improve as much in the increased-spacing condition is that they didn’t have much room to improve. They were already good readers and were at ceiling on the test. It is unlikely that any kind of experimental manipulation will make a good reader a better reader. Which leads me to my suggestion for replicating this study. Don’t replicate it!

I can’t see how using either age- or reading-age matched controls (i.e., good readers) will allow adequately testing of the hypothesis that increased letter-spacing results in improved reading ability in people with dyslexia because of the point I made above: it is unlikely that any kind of experimental manipulation will make a good reader a better reader. In my view, the next piece of research will need to use equivalent groups of people with dyslexia, one of which receives the extra-letetr spacing manipulation and who does not. It is also worth noting that recent research has shown that the effects of another visual manipulation (coloured overlays) on reading ability is not reliable on repeat testing (Henderson et al., 2012) so any future research should probably run the test multiple times for each condition. Finally, if the research is conducted in English, it would be interesting to see if increased letter-spacing changes error rates (for better or worse) for words that involve single grapheme-to-phoneme correspondence compared to those that have digraphs (e.g., chip and rain) or trigraphs (e.g., slight). It might also be interesting to see if increased letter-spacing reduces errors for words in which letter-positiuon errors can occur (e.g., trail-trial).

Until we see these data I’m keeping my ink dry.

http://www.sciencedaily.com/releases/2011/09/110928180414.htm  -Science daily

Brain Imaging Study Shows Physiological Basis of Dyslexia

Sep. 28, 2011 — Researchers at the Stanford University School of Medicine have used an imaging technique to show that the brain activation patterns in children with poor reading skills and a low IQ are similar to those in poor readers with a typical IQ. The work provides more definitive evidence about poor readers having similar kinds of difficulties regardless of their general cognitive ability.

Schools and psychologists have historically relied on a child's IQ to define and diagnose dyslexia, a brain-based learning disability that impairs a person's ability to read: If a child's reading achievement was below expectation based on IQ, he would be considered dyslexic, while a poor reader with a low IQ would receive some other diagnosis. But these new findings provide "biological evidence that IQ should not be emphasized in the diagnosis of reading abilities," said Fumiko Hoeft, MD, Ph.D, an instructor at Stanford's Center for Interdisciplinary Brain Sciences Research, who is senior author of the study, which will appear in an upcoming issue ofPsychological Science.

The new results come in the wake of recent behavioral studies showing that phonological deficits -- that is, difficulties in processing the sound system of language, which often leads to difficulties in connecting the sounds of language to letters -- are similar in poor readers regardless of IQ. Indeed, the 2004 reauthorization of the Individuals with Disabilities Education Act mandated that states no longer require school districts to use IQ tests in identifying individuals with learning disabilities such as dyslexia.

"There's a disassociation between what is established in research and what is happening in practice," said Hoeft, explaining that many U.S. schools still rely on a discrepancy between reading achievement and IQ to define and diagnose dyslexia. At first glance, she added, it would seem to make sense that poor readers with typical IQs would have different learning challenges than those with low ones.

The use of IQ in diagnosing dyslexia, which affects 5 to 17 percent of U.S. children, has real implications for poor readers. If children aren't diagnosed as dyslexic, they don't qualify for services that a typical dyslexic does, and they're not taught strategies to overcome specific problems in the way they view and process words.

To further understand what happens in the brains of poor readers with different IQs, Hoeft turned to imaging. She and her colleagues expected poor readers with typical IQs to exhibit similar patterns of brain activation as poor readers with low IQs. Their experiments, she said, were intended to confirm that the two groups had the same neurophysiological basis for impaired phonological processing and that their reading problems were not related to IQ.

The study involved 131 children, ranging from 7 to 16 years old, from Allegheny County, Penn., and the San Francisco Bay Area. The children were put into three groups: poor readers with typical IQ, poor readers with low IQ and typical readers with typical IQ. The children then took a reading test and underwent a brain-imaging technique called functional magnetic resonance imaging, or fMRI, as they completed a task that involved judging whether two visually presented words rhymed (e.g., bait and gate) or not (e.g., price or miss).

In both samples, the typical readers had significantly higher reading-related scores and more accurate performance on the rhyme-judgment task than the two other groups. And there were no significant differences between the two groups of poor readers on these measures.

In the fMRI analysis, researchers found that both groups of poor readers exhibited significantly reduced activations relative to typical readers in the left inferior parietal lobule and left fusiform gyrus. The researchers also used a sophisticated analysis to determine that the brain patterns of each group of poor readers looked liked those of the other group of poor readers more than 80 percent of the time, and did not often resemble the patterns from the normal readers.

Hoeft noted that the results are timely. The Diagnostic and Statistical Manual of Mental Disorders, the standard diagnostic guide for mental illnesses and brain disorders, is currently being revised, and there is a proposal to change it so that IQ wouldn't be taken into consideration when diagnosing dyslexia. (The new version, DSM V, will be released in 2013.) This work, she said, is the, "first study reporting biological neuroimaging evidence to support" that change.

"Convergent psychological, educational and now neurobiological evidence suggests that the long-standing and widely applied diagnosis of dyslexia by IQ discrepancy is not supported," the researchers wrote in the paper.

Hoeft and her colleagues also point out that these and other findings indicate that, "any child with a reading difficulty, regardless of his or her general level of cognitive abilities (IQ), should be encouraged to seek reading intervention."

Hoeft said she will continue her work in this area and is hoping to use imaging to predict outcomes of poor readers. She also plans to look at younger readers to see if imaging can be used to diagnose children at younger ages.

The study's two lead authors are Stanford graduate student Hiroko Tanaka and Jessica Black, Ph.D, of Boston College. The other Stanford co-authors are graduate student Leanne Stanley; Shelli Kesler, Ph.D, assistant professor of psychiatry and behavioral sciences; and Allan Reiss, MD, the Howard C. Robbins Professor of Psychiatry and Behavioral Sciences, a professor of radiology and the director of Stanford's Center for Interdisciplinary Brain Sciences Research. Researchers from the Massachusetts Institute of Technology are also co-authors.

The work was supported by the William and Flora Hewlett Foundation, Richard King Mellon Foundation, Ellison Medical Foundation, National Institute of Child Health and Human Development, Lucile Packard Foundation for Children's Health, Spectrum Child Health & Clinical and Translational Science Award, Dyslexia Foundation and the National Alliance for Research in Schizophrenia and Depression.

Adults with dyslexia have problems with non-speech sounds too

http://phys.org/news194589535.html

Adults with dyslexia have problems with non-speech sounds too

 June 1, 2010 by Lin Edwards (PhysOrg.com) -- 

Dyslexia is usually associated with persistent reading, spelling, and sometimes speech difficulties that are hard to overcome. One theory proposed to explain the condition is that people with dyslexia suffer from a more fundamental deficit in auditory processing than just interpretation of the spoken or written word, but this idea has produced much debate. Now scientists in Europe have shown that adults with dyslexia do have a specific auditory processing impairment that is not specific to speech sounds. Ads by Google Exercise Your Brain - Games You Didn't Know Existed to Fight Brain Decline and Aging. - www.lumosity.com Dyslexia is a learning disability that can hinder the development of spoken and/or written language skills. In visual dyslexia there is a tendency to reverse letters or numbers and to struggle with writing symbols in the right order. In auditory dyslexia sounds may not be heard correctly or may seem jumbled. There have been many theories about the possible causes of the condition, and much debate about whether the condition only involves comprehension of language or lies in problems with auditory processing in general. A team of scientists from Belgium, Switzerland and the UK designed experiments that tested auditory dyslexic adults (and non-dyslexic controls) using carefully controlled sound stimuli. They played recordings of consonant and vowel sounds in both speech and non-speech versions, and determined how well the subjects understood the sounds. For consonants, they played a recording that rapidly alternated between the sounds “ba” and “da,” in a speech version and then in a non-speech version that altered the pitch of parts of the sound, and mixed them up. For example, a non-speech version of “ba” could start with a high-pitch “b” and end with a low-pitch “ah,” or vice versa. They then repeated the experiments with speech and non-speech versions of the vowel sounds “u” and “y”. The results showed that the subjects with dyslexia did find it difficult to distinguish between consonants but fared as well as the non-dyslexic subjects with vowel sounds. The non-dyslexic subjects had little trouble distinguishing the non-speech versions of the consonants but those with dyslexia were confused by them even if the non-speech tones were only slightly unnatural, which suggests their problem may be a difficulty in processing variations in intonation in sounds, whether from speech or other sources. The results of the experiments may mean people with dyslexia could be able to undergo auditory training to help them learn to distinguish consonant sounds better by focusing on shifts in pitch. The paper is published in the Proceedings of the National Academy of Sciences.

Read more at: http://phys.org/news194589535.html#jCp