Psy 346: subtyping of reading disorders
(2-20-12)

Subtyping:

Language pattern of Reading Disability

"phonological-deficit hypothesis" (Shaywitz, 1998)

"dysphonetic dyslexia" (Boder, 1973), "auditory-linguistic dyslexia" (Pirozzolo, 1979), "language pattern reading disorder"

The primary cause of reading problems is a core deficit in phonological processing. Phonological awareness is the ability to use the phonetic segments of speech, including awareness of and use of the sound structure of language. "Phonologically based reading disabilities" show high heritability estimates, weakness on a variety of verbal measure, attentional deficits, a high comorbidity with ADHD (Teeter & Semrud-Clikeman, 1997). There is often an early (and resolved by later ages) report of speech and/or language delays or deficits. There may be a history of early ear infections. There is often a family history of learning problems, especially reading problems. Spelling errors are usually phonetically inaccurate--poor "sound-symbol association."

Relatively poor Verbal IQ scores, mispronounciations in oral reading, poor scores on auditory discrimination and word finding tests (Barkley, 1981).

most common, possibly at least 60-80% of identified cases

A recent review suggests that: "inadequate facility in word identification due, in most cases, to more basic deficits in alphabetic coding is the basic cuase of difficulties in learning to read." (Vullution, Fletcher, Snowling, & Scanlon, 2004, p. 2).

Visual-spatial pattern (enduring perceptual-motor difficulties)

difficulty "revisualizing a word"; associated with problems in drawing, copying, constructional activities. Spelling errors are usually phonetically accurate but too many or too few letters may be used--the "shape" of the word is obviously wrong. "visual-orthographic deficits in reading" (Teeter & Semrud-Clikeman, 1997)

"dyseidetic dyslexia" (Boder, 1979), "visual-spatial dyslexia" (Pirozzolo, 1979)

minority pattern, possibly 5-15% of identified cases, may be more common at younger ages

Do poorly on tests of visual-spatial construction: drawing, copying; relatively low on Performance IQ tests; poor sight readers of words, make phonetically accurate spelling errors (Barkley, 1981).

Mixed pattern

rare, possibly 3-5%--10-20% of identified cases

"mixed dyslexia" (Boder, 1979)

Show little discrepancy between VIQ and PIQ, poor articulation, handwriting, and recall of sequences (Barkley, 1981)

may be at greatest risk to evolve into "hard core illiterate" population as adults

"Normal" LD pattern

group without identified psychological or neuropsychological deficit

rare, but has consistently been found in several studies