18 Feb Auditory-Linguistic Dyslexia
The terms auditory-linguistic dyslexia and visual-spatial dyslexia are often used by scholars to describe two main types of dyslexia.
Generally speaking, the auditory-linguistic dyslexic tends to perform poorly in several language-related functions. According to Denckla, Mattis, and Pirozzolo, such a child has a lower Verbal (usually below IQ 90) than a Performance (usually at least IQ 95) score on a standardized test such as the WISC-R. Critchley and Pirozzolo noted delayed acquisition of speech and language skills, while Denckla and Mattis observed naming difficulties as well as repetitive, circumlocutory or paraphasic speech. Pirozzolo named difficulties in sight-sound associations, short-term verbal memory deficits, difficulty recalling orally given instructions, and slow and laborious reading. Critchley presented evidence of vocalization and lip movement during silent reading. Because of the associated semantic and syntactic disorders observed in the speech and writing of the adult dyslexic, Critchley described such an individual as “too often lame in his manipulation of language symbols.” By and large, these dyslexics lack phonic word-attack skills and prefer visual activities such as whole-word sight reading.
Among the manifestations which characterize the auditory-linguistic dyslexia, according to author Saroj D. Sutaria (Specific Learning Disabilities: Nature and Needs), are difficulties in sound-symbol association, auditory discrimination difficulties, problems in auditory analysis and synthesis, auditory sequencing difficulties, auditory memory problems, omissions, additions and substitutions, mispronunciations and hesitations and repetitions.
1.) Sound-symbol association problems
Johnson and Myklebust described dyslexia as a breakdown in the interneurosensory processing. This means that the child is unable to make the association needed between the graphemes and its phonemes. The child’s biggest difficulty lies in comprehending that although the English alphabet consists of 26 letters, there are only 44 phonemes; that the names of the letters are different from their phonemic properties; that few letters have only one sound which remains constant; that combination of certain consonants and vowels produce entirely different sounds; that certain consonant-vowel combinations change the sound; that there are hard, soft and silent sounds depending on the positioning of the letters in the words, etc. The difficulty is compounded when the child also has a memory disorder.
The child has difficulty differentiating between similarities and differences in sounds of letters and words. This problem is aggravated when the child is unable to sort through or ignore background noises and voices. The most apparent difficulties are seen in certain consonantal sounds, such as /b/ and /p/, /m/ and /n/ or /d/ and /t/, etc. Even more difficult are short vowel sounds, especially /e/ and /i/. Words frequently misread are three-letter words in which only the vowel sound is different, for example, /pen/, /pin/. As Critchley noted, the learning disabled child is unable to detect the differences in the auditory properties of letters and words.
3.) Difficulties in auditory analysis and synthesis
The learning disabled is unable to read unfamiliar words because he/she lacks a structural analytical approach so necessary to this task. Structural analysis requires the identification of morphemes which includes prefixes, suffixes, root words, and the like. Following the identification of these smaller units, they must be blended together as a whole. Critchley observed, the child has a tendency to guess wildly at the word. This is usually done on the basis of the first letter and sometimes on its length.
4.) Auditory sequencing difficulties
Basically, the temporal order of sounds in words is disturbed. The child is unable to retain in short-term memory store the sequence of sounds long enough to reproduce them in the correct order when reading out loud. Thus, while the individual letters may be associated with their sounds correctly and syllables identified accurately, when it comes time to pronounce them together the child reverts the order, as, for instance /emeny/ in place of /enemy/. Senf reported evidence of this in the learning disabled whose primary problems may be in word mixing in compound words, for example /mindwill/ instead of /windmill/, /shoehorse/ for /horseshoe/, etc. It is Denckla’s observation that children with this type of problem tend to change with age from having problems in both reading and spelling to spelling alone, although they might continue to have difficulty with the phonetic aspects of a foreign language.
5.) Auditory memory problems
Retrieval of sound of letters and words for spontaneous use may be difficult for the auditory-linguistic dyslexic because of an inefficient system of processing in long-term memory storage. The difficulty in recalling specific sounds and names may account for certain substitutions which the learning disabled make, as, for example, /dad/ for /father/ or /baby/ for /daughter/. Not only are the substituted words easier to pronounce, but their pronunciation is based on regular phonics principles while the others are not. Pronunciation of words like /father/, /daughter/ etc., requires the child to remember the irregularities in making symbol-sound associations.
6.) Omissions, additions, substitutions
The learning disabled tend to omit single phonemes or syllables in word pronunciation. Thus /walking/ may be read as /walk/, /boxes/ as /box/, /rust/ as /rut/, /bent/ as /bet/, etc. While the first two types may not significantly affect the meaning derived from the content, the remaining two would render the statement meaningless. Sometimes, whole words may be omitted. Although whole-word omissions are usually the result of visual oversight, the anticipation of difficulties in pronunciation of a particular word may cause the child to simply ignore it. Some children tend to add words or sound units, as, for example, /the little baby/ in place of /the baby/ or /baby sister/ instead of /baby sitter/, etc. Frequently heard phrases which become automatically associated with each other tend to be added more frequently than others, such as /Once upon a time there was/ in place of /Once there was/, etc. Wiig and Semel reported that words beginning with /s/ blends tend to cause some learning disabled to omit some sound units in words, as, for example, /spit/, /sit/ for /split/, while in others to add sounds, as, for example, /split/ or /slit/ for /sit/. As for substitutions, we have already noted one type under memory problems. These may be described as meaningful substitutions in the sense that their use does not alter the meaning of the text greatly. Other substitutions, however, may change or distort the meaning. Mattis suggested that some of the substituted words may sound like the correct words but are not. For example, the child may read /hijackers/ instead of /hitchhikers/ or /optimist/ for /optometrist/, etc.
A variety of mispronunciations occur in the auditory-linguistic dyslexic. Critchley noted incorrect pronunciation of vowels. Already noted it the difficulty that the child has with short vowels. The child may not fully comprehend the difference between short and long vowel sounds, thus confusing for example /mat/ and /mate/, /hat/ and /hate/. The variations in sounds that certain words produce are especially baffling for this child. For instance, words /hut/, /mut/, /put/ have, with the exception of initial consonant sounds, identical properties and yet the pronunciation of the last is entirely different. Similarly, in words /have/, /gave/, save/, initial consonants are different but the rest is the same in all three words, yet the pronunciation is different in the first while the other two rhyme. Other mispronunciations may affect initial, medial of final sounds of individual consonants or consonant blends, digraphs, or diphthongs. Wiig and Semel noted special difficulties with blend which have /l/, /w/, or /r/ in second position. Insertions of extra sounds produce mispronunciations, as in /trick/ for /tick/, just as omissions do. Incorrect stress on syllables in words may also produce mispronunciation.
8.) Hesitations and repetitions
Uncertainty about correct pronunciation of a word often causes the child to pause incorrectly between words or to exhibit perseverative tendencies, that is, the child will repeat the preceding phrase or word several times before attempting the problem word.