Elizabeth Johnston, Investigating Minds, 12.9.97.

Lecture 23: Dyslexia

Dyslexia literally means a difficulty with words, but is used to refer to reading difficulties. Most people classified as "learning disabled" have dyslexia.

What Characteristics Accompany Dyslexia? ( from The Orton Society)

Few dyslexics exhibit all the signs of the disorder. Some common signs are:

Some History

The term "learning disabilities" was not coined until the 1960s, but the study of reading difficulties dates to the turn of the century. Early researchers, Morgan and Hinshelwood, were ophthalmologists who, not surprizingly, focused on visual aspects that might underlie the reading difficulty and termed it "congenital word blindness". In 1937 the neurologist, Orton, arguably the most famous of dyslexia researchers, introduced the term "strephosymbolia" which means "twisted symbols" referring to the frequent letter reversals found in dyslexic reading and spelling. Hinshelwood and Orton drew many inferences from acquired reading disorders due to brain injury and thus focused heavily on biological causation. Orton believed that reading disability resulted from a delay in or failure of the establishment of hemispheric dominance for language, a notion that is echoed in modern theories of neurological dysfunction underlying dyslexia. The Orton-Gilligham approach to remediation relied heavily on structured instruction in phonics combined with multisensory activities and many of the phonetics programs currently in use are based on Orton's program. Spear-Swerling and Sternberg (1997) state that these programs are frequently helpful, but they probably do not work for the reasons that Orton believed they did.

1963 is the generally accepted date for the formal foundation of LD as a field of educational practice. At this time the accepted approach was an "underlying abilities paradigm". Reading achievement was thought to depend upon underlying visual-perceptual, auditory-perceptual, memory and even motor abilities. The emphasis was on testing for and training these underlying abilities separately from any measurment of or instruction in reading. In the 1970s many research studies demonstrated that the measures of underlying abilities lacked relaibility and validity. Even more damaging to the underlying abilities paradigm was the finding that the efforts at training abilities did not usually result in improvements in reading achievement.

In response to the failure of the underlying abilities paradigm in the 1970s the "direct instruction" paradigm held sway. Under the influence of behaviorism the task of reading was broken down to a fine level and taught in a highly structured way. In the 1980s the LD field increasingly turned away from strongly task-analytic versions of direct instruction in favor of the holistic "whole language" approach.

Back to "Phonics" vs "Whole Language"

The history of reading instruction can be viewed as a manic swinging of the pendulum from "phonics" to "whole language". I discussed these views briefly in the last lecture, but I'll set them out more systematically here.

Phonics Whole Language
Initial emphasis Learning to decode words Comprehension
Amount of direct instruction in decoding High Varies from moderate to very low
Decoding is practiced in isolation as well as in context Yes Usually not
Nature of decoding instruction Highly systematic; may be analytic or synthetic Not systematic; usually more analytic than synthetic
Reading and content instruction are integrated Usually not Yes
Nature of beginning texts Phonetically controlled Not controlled (although predictable texts may be used)
Underlying view of reading acquisition Reading acquisition requires formal instruction, especially in decoding Reading acquisition is "natural"
Adapted from Spear-Swerling and Sternberg (1997), page 163.

Phonics instruction must be integrated with the reading of texts in order for children to apply their knowledge of sound-spelling relationships. This is most easily achieved if the texts used are decodable for the child: they can use sound-spelling relationships they have already learned. If text is less decodable children are forced to use prediction or context to figure out words. The research conducted on the effectiveness of prediction as a strategy for word recognition shows that while prediction is valuable for comprehension it is not useful for word recognition. In other words, having to guess a word from the context does npt automatically translate into recognizing that word the next time it is encountered in a different context. Further, many different empirical studies have indicated that naturalistic text is not that predictable. Some sense of the difficulties inherent in using such a strategy is provided below. The following is a sample of text from 'Jack London' with the parts that a young child learning to read was unable to decode omitted.

He had never seen dogs fight as these w__ish c__ f__t, and his first ex____ t____t him an unf______able l_____n. It is true, it was a vi___ ex______, else he would not have lived to pr__it by it. Curly was the v____. They were camped near the log store, where she, in her friend_ way, made ad_____ to a husky dog the size of a full-____ wolf, th____ not half so large as _he. __ere was no w__ing, only a leap in like a flash, a met__ clip of teeth, a leap out equal_ swift, and Curly's face was ripped open from eye to jaw.

It was the wolf manner of fight__, to st___ and leap away; but here was more to it than this. Th____ or forty huskies ran -o the spot and not com___d that s____t circle. But did not com____d that s____t in_____, not the e___ way with which they were licking their chops. Curly rushed her ant_____,who struck again and leaped aside. He met her next rush with his chest, in a p_____ fash___ that tum___ed her off her feet. She never re____ed them. This was __at the on____ing huskies had w_____ for.

Examples of phonemic awareness tasks

Phoneme deletion: What word would be left if the /k/ sound were taken away from cat?
Word to word matching: Do pen and pipe begin with the same sound?
Blending: What word would we have if you put these sounds together: /s/, /a/, /t/?
Sound isolation: What is the first sound in rose?
Phoneme counting: How many sounds do you hear in the word cake?
Deleting phonemes: What sound do you hear in meat that is missing in eat?
Odd word out: What word starts with a different sound: bag, nine, beach, bike?
Sound to word matching: Is there a /k/ in bike?

A Recent Success Story

In 1995 Paula Tallal, Michael Merzenich and their collaborators reported on a resounding success in remediating reading difficulties in children with LLI (Language Learning Impairment). Children diagnosed with LLI have difficulties with oral language and subsequent severe difficulties learning to read. Tallal & Merzenich postulated that the LLI children had particular difficulty processing fast sounds such as the hard labial and alveolar consonants /b/, /p/, and /d/ where the crucial distinguishing information lasts on the order of 40ms. In contrast, vowel rich sounds resonate for 100ms or longer. To test this hypothesis Tallal, Merzenich and their collaborators slowed the consonants to half their normal speed and found that LLI children could then distinguish the sounds. The next step was to investigate whether this difficulty which is presumed to be biological in origin could be ameliorated by training. In other words, 'Could the brains of LLI children be retrained to discriminate rapid phonemes?' To test this possibility Tallal et al devised some "aerobics for the brain" in the form of video games. Eighteen LLI children, ages 5-10 years, came to "summer camp" for a month and received three hours a day of training in discriminating fast moving sounds. They moved systematically from elongated and selectively amplified versions of the sounds to the messy and rapid sound patterns we ordinarily deal with. After that month, their language comprehension improved by about two years, and 6 months later the massive jump in language comprehension abilities persisted.

Traditional Construct of RD Alternative View of Reading Difficulties
RD is a unique disorder of reading Individuals with RD are on a continuum with other poor readers (and with good readers).
Individuals with RD have an intrinsic "processing disorder"  Most poor readers have difficulties with word decoding and phonological processing. In some cases, these difficulties may constitute an actual "disorder," but in many cases, they likely represent the low end of a normal continuum of processing. In either event, processing difficulties are shaped by experiences and the environment as well as by innate biological influences.
Reading disability is caused by an intrinsic biological disorder. A rare biological disorder of poor reading certainly may exist. However, the vast majority of school-identified children with RD do not appear to have such a disorder.
Reading disability involves "unexpected" poor reading. Human abilities are multidimensional, and most people have strengths and weaknesses across different types of abilities. Learning to read draws upon a variety of linguistic abilities---phonological, orthographic, semantic, syntactic, etc. Poor reading often is associated with specific phonological weaknesses, but poor readers may have considerable strengths in other linguistic (and non-linguistic) abilities.

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