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Information processing and reading competencies in hydrocephalic children
Information Processing and Reading Competencies in Hydrocephafic Children
George P. Prigatano and Harriet K. Zeiner
Presbyterian Hospital University of Oklahoma
ABSTRACT Cross-sectional studies of heterogeneous groups of hydrocephalic children report reading lags of 18 months compared to controls matched for physical disability. This longitudinal study investigated the relationship between the global skill of reading and basic sensory information processing capacities in three homogeneous gzoups of children: 21 children with uncomplicated hydrocephalus; 24 children who made excessive letter reversals (LR), and 30 normal school children. All children had normal range IQ, and were 4-10 years of age. Three information processing tasks were administered once per year for two years: a tactile matching-to-sample, a visual tachistoscopic matching-to-sample task and an auditory dichotic listening task. Woodcock Reading Mastery Tests were given to measure reading proficiency. Hydrocephalics demonstrated a number of consistent information processing deficits when compared to letter reversal and normal school children. Hydrocephalics showed tactile infonnation processing deficits, quantitatively and qualitatively, both years. Hydrocephalic children showed consistent qualitative differences in visual information processing both years. Hydrocephalics did now show consistent differences (i.e., both years) in auditory information processing. Global reading proficiency appeared to be normal both in children with uncomplicated hydrocephalus and letter reversal children with normal range IQ. Some subcomponent reading skills were impaired in hydrocephalics. Several significant correlations were found between information processing errors and reading scores in both hydrocephalics and letter reversal children. However, these correlations were considered unreliable due to either (1) a failure to reach significance the second year or (2) a sign change from positive to negative by the second year of testing. The conclusion was drawn that there were no consistent associations between specific tactile, visual, and auditory information processing deficits and reading proficiency in any of the three groups tested. These results are discussed in light of the importance of longitudinal research with homogeneous groups as opposed to cross-sectional sampling in children with proficiency skill problems.
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INTRODUCTION We have been conducting longitudinal neurobehavioral research with a group of children who suffer from congenital communicating hydrocephalus. In the past, we have described the information processing capacities (Zeiner and Prigatano 1982) and neuropsychological functioning (Prigatano, Zeiner, Pollay, and Kaplan, in press) of these children. The present study attempts to relate the academic skill of reading to basic information processing skills in young children (4-10 years) with shunted congenital hydrocephalus. Before describing the linguistic and reading impairments known to occur in these children, a brief review of the neuropathy and information processing problems associated with hydrocephalus will be discussed. Neuroanatomay of Hydrocephalus Within the cerebral hemispheres lie four major spaces called ventricles. The largest spaces invade the frontal, temporal and parietal-occipital lobes, and are known as the lateral ventricles. The third and fourth ventricles are connected via a hollow pathway known as the cerebral aquaduct. Around and through these ventricular spaces flows cerebrospinal fluid (CSF) in a specified route of circulation. Obstruction of the flow of CSF anywhere throughout the system can cause a buildup of fluid within the ventricles. This produces the condition known as hydrocephalus. Since brain tissue is more compressable than either CSF or the skull, expanding fluid buildup results in thinning of brain mass. The compressive effects of pressure result in thinning of myelin, loss of white matter of the brain, and may eventually include respiratory arrest as intracranial pressure increases. Children with hydrocephalus diagnosed at birth may also suffer from neurocircuitry problems. Migration of cells which later form corticofugal connections begins along and is determined by placement of the ceils on the walls of the lateral ventricles in utero. Thus, fetal hydrocephalus may result in neurocircuitry wiring abnormalities in addition to the compressive effects of raised intracranial pressure (Rakic 1981). Treatment of hydrocephalus consists of placing a mechanical shunt in the lateral ventricles which allows excess CSF to drain via a subcutaneous catheter into the peritoneal cavity. This results in a reduction of ventricle size to within normal limits (or even smaller). Frequently brain tissue re-expands, with myelin sheath deposits increasing in size. Basic Information Processing in Hydrocephalic Children In a previous report (Zeiner and Prigatano 1982) we described the ability of hydrocephalic children to process visual, auditory, and tactile information. This
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work was prompted by the suggestion of Miller and Sethi (1971) that the pressure of CSF resulting from enlarged ventricles could mechanically stretch corpus callosum fibers. Callosal fibers allow transmission of information from one side of the brain to the other. Miller and Sethi believed hydrocephalic children suffered from a "partial" callosal syndrome, i.e., an inefficiency of interhemisphere transfer of information. Since mirror-image errors have also been related to callosal dysfunction in animals (Noble 1966), we compared hydrocephalic children to two groups of controls: normal children, and children who made excessive letter reversals. While the experimental tests used were shown to be sensitive to individuals with known caUosal lesions, the study failed to demonstrate a "partial" callosal sydrome in hydrocephalic children. Their information processing abilities demonstrated numerous intra- as well as interhemispheric information processing difficulties compared to controls. Letter reversal children were often similar to controls, but consistently fell between normals and hydrocephalic children on the various information'processing tasks. Linguistic Functioning in Hydrocephalic Children
A number of observers have reported that some hydrocephalic children talk excessively (Hadenius et al. 1962; Ingram and Naughton 1962; Laurence and Coates 1962) and that their speech is lacking in content (Badell-Ribera, Shulman, and Paddock 1966; Swisher and Pinsker 1971; Spain 1974). Taylor (1961) pointed out that these children do well in repeating stories from memory, but cannot explain the content of the stories. These limitations of language ability are reflected on intelligence tests. They may do well on some verbal tasks, such as picture vocabulary, but fail on verbal tasks which call for reasoning and comprehension. Experimental studies of children with hydrocephalus indicate that they do not talk more than other children of the same age (Fleming 1968; and Diller, Paddock, BadeU-Ribera, and Swinyard 1966), i.e., they are not quantitatively different. Hydrocephallc children differed from controls on qualitative rather than quantitative measures of verbal output on the Children's Apperception Test (Fleming 1968). They made significantly greater number of inappropriate responses, particularly in situations of stress. Taylor (1965) also described qualitative differences in hydrocephalic speech. He found a discrepancy between language produced in a less distracting, formal test situation and language produced in an unstructured setting. In a conversational setting, hyperverbal hydrocephalic children exhibited a profile which reflected the superficiality of their output on the Illinois Test of Psycholinguistic Abilities (ITPA). They earned low scores on the auditory-decoding subtest (understanding what is heard, e.g., "Do apples fly?" and the auditory-vocal association subtests, (relating
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spoken words in a meaningful way, e.g., soup is hot, ice cream is cold. There was no impairment on the auditory.automatic subtest which consists of adding a correct grammatical form to complete a sentence, and is a measure of syntax (Swisher and Pinsker 1971). Swisher and Pinsker's finding of normal grammatical functioning is similar to Spain's result that hyperverbal hydrocephalic children produce below average scores on the Reynell Scale verbal content and comprehension test, but average scores for syntax development. Thus, several studies have found normal grammar and syntax development coupled with below average comprehension performance on verbal tasks. In addition to formal linguistic difficulties, children with congenital hydrocephalus have also been reported to lag behind control groups matched for physical disability by 18 months in reading proficiency in both the United States (DiUer, Baddell-Ribera, and Swinyard 1966) and in Great Britain (Laurence and Coates 1962). In the present study, we attempted to relate reading proficiency with basic visual, auditory, and tactile information processing skills in a subgroup of hydrocephalic children. Reading is a global skill which can be broken down into subcomponent skills, e.g., the ability to identify letters, read vocabulary words, sound out words, the ability to understand words and use them in analogies, and the ability to complete sentences. These are skills which are presumed to be necessary for normal reading proficiency by educators, reading test constructors and researchers in learning disability. We were interested in the relationship between the global skill of reading, the subcomponent skills used to compute global reading proficiency, and basic sensory information processing capacities. The following specific questions were posed: 1. Do children with uncomplicated hydrocephalus show normal reading proficiencies? 2. Is there a relationship between reading proficiency, or a subcomponent of reading proficiency, and information processing difficulties in hydrocephalic, normal, or letter reversal children?
METHOD From a methodological point of view, it is important to make a distinction between complicated (presence of other brain anomalies in addition to hydrocephalus) and uncomplicated communicating hydrocephalus. Many of the complications frequently associated with hydrocephalus (e.g., seizure disorders, meningitis, porencephalic cysts) are themselves known to be associated with cognitive impairments. We were concerned with information processing and academic impairments
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associated with the congenital hydrocephalic process per se, and not with the variety of cognitive impairments which might be due to a combination of both hydrocephalus and frequently occurring brain lesions. Subjects A detailed description of the children studied in this project is available elsewhere (Zeiner and Prigatano 1982; Prigatano et al., in press). For purposes of this report, however, the following facts are pertinent. Twenty-one (21) hydrocephalic children between the ages of 4 and 10 years, with shunted uncomplicated congenital hydrocephalus, and who were judged to have at least low normal intelligence were studied. Thirteen of these children were male, 8 were female. Thirteen were right handed, 6 were left handed, and 2 had mixed handedness. Their mean age was 6.2 years. Twenty-four letter reversal (LR) children, between the ages of 5 to 9 years, without any history of neurological or psychiatric difficulties, and who were judged to have at least low normal intelligence were also studied. These children were referred by their teachers as making excessive letter reversals. These reversal errors occurred in both written and spoken language. Eleven were male, 13 were female, 22 were right handed, 1 was left handed, and 1 had mixed handedness. Their mean age was 6.5 years. Thirty (30) normal elementary school children between the ages of 4 to 10 years, with at least low normal intelligence, were also studied. Fifteen were male and 15 were female. Twenty-six were right handed, 1 was left handed, and 3 had mixed dominance. Apparatus and Tasks: Information Processing Measures Three information processing tasks were used in the initial report: A tactile matching-to-sample task, a visual tachistoscopic matching-to-sample task, and an auditory dichotic listening task. The latter two tasks directly dealt with linguistic information, the first did not. The tactile task required the subject to feel a nail head design hidden from view with one hand. The subject was, then, required to pick out the same tactile stimulus from a 6 stimulus array (also hidden from view) with either the same hand or the opposite hand. Right hand trials first versus left hand trials first were counterbalanced; sixteen trials were given in all. Subjects were asked not to name the stimuli aloud, but to simply identify the same stimlus they had previously touched. The visual tasks required the subject to centrally fixate on a tachistoscopically presented colored dot which the subject named. A letter stimlus (b, d, q, p, and E) was then presented tachistoscopically to either the temporal right or temporal left
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visual hemifield for a very brief period (60-125 msec., determined by workup prior to the visual testing). A central fLxation colored dot was again given. A second visual stimulus was, then, given to either the same visual hemifield as the first stimulus or to the opposite visual hemifield. The second stimulus was either the same as the first stimulus or was a mirror image reversal. The subject's task was (1) to name the colored dot (to insure central fLxation) and (2) to say whether the two successive stimuli were the "same" or "different." Subjects were asked not to name the letters. Visual hemffields for both initial and second stimulus presentation, letter presented, number of reversals, and responses (i.e. "same or different") were counterbalanced. Forty-eight trials were presented. The auditory task was a dichotic listening paradigm. Consonant/vowel sounds (ga, ba, da, ka, ta) were given monaurally via earphones. The subject was required to say the sound aloud. Each ear was tested separately. Then, two different consonant/vowel sounds were presented simultaneously, one in the right ear and the other in the left ear. The subject's task was to name both sounds given. The earphones were then reversed, and the entire test, both monaural and dichotic presentations, was repeated. Right ear first versus left ear first in the monaural condition was counterbalanced. A total of thirty-six monaural trials was given in each ear. Seventy-two dichotic trials were presented. These three tasks are discribed in more detail in Zeiner and Prigatano, (1982). All three information processing tasks were repeated the second year.
Reading Proficiency Measures: Woodcock Reading Mastery Tests The Woodcock Reading Mastery Tests, Form A, were given the first year, Form B the second year. The Woodcock Reading Mastery Tests consist of a battery of five individually administered reading tests for use from kindergarten through grade 12. The five tests were: letter identification (LID), word identification (Word ID), word attack, (phonics), word comprehension (analogies), and passage comprehension. The component tests were, then, used to compute a total Reading Percentile Score. The Letter Identification Test contained 45 items which measure the subject's ability to name letters of the English alphabet. Test items include a variety of common and, in some cases, uncommon styles of type. The letter items are arranged in order of difficulty within the test and the subject's task is to name each letter. Children who are at the beginning of the first grade are generally able to name several letters, particularly those involving upper- and lower-case Roman styles. For more details of this subtest and the ones below, please see the Woodcock Reading Mastery
Test Manual.
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The Word Identification Test consisted of a set of 150 words ranging in difficulty from the first words presented in a typical beginning reading program (e.g., the, go, and) to words of above average difficulty for superior students in the twelfth grade (e.g., facetious, beatitude, picayune). The Word Attack Test contained 50 items which measure the subject's ability to identify nonsense words via phonetics. At the lower end of the test the nonsense words were simple consonant/vowel combinations such as "dee" and "lat." Multisyllabic words such as "ipdan" and "depmonlel" were presented at the upper end of the test. Represented within the set of nonsense words were most consonant/ vowel sounds, common prefixes and suffixes, and frequently appearing irregular spellings of vowels and consonants (e.g. "ph" for "f," "igh" for long 'T'). The Word Comprehension Test contained 70 items designed to measure a subject's knowledge of word meanings. An analogy format was used. The subject's task was to read the first pair of words in an analogy, then read the first word of the second pair and say a word which would complete the analogy. (e.g., bird-fly,
fish-). Passage Comprehension contained 85 items constructed with a modified close procedure. The subject's task was to silently read a passage which had a word missing and tell the examiner an appropriate word to go in the blank space. Results from the five tests in the battery were combined to provide a composite of overall reading skill. Percentile scores for each test were based on national norms standarized on grade levels divided by month.
Statistical Analyses The data were analyzed with analysis of variance, Duncan Multiple Range Tests, paired t-test, Pearson-r product moment correlations and, when appropriate, analysis of covariance. RESULTS Reading Proficiency in Hydrocephalic Children The initial question posed was whether or not hydrocephalic children demonstrated impaired reading skills. Table 1 summarizes the ANOVA F values and probabilities for each of the Woodcock Reading Mastery Tests for the three groups of children studied. Significant differences were obtained in word recognition (vocabulary), word comprehension (analogies), passage comprehension, and total reading scores during the first year of testing. Table 2 illustrates that hydrocephalic children were consistently reliably different from normal controls, but were equal to letter reversal children. Also, letter reversal children were not reliably different from controls, but were between hydrocephalic and control groups in their level
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Table I Woodcock Reading Master Scores: Hydrocephalics vs LR vs Controls ANOVA Results
Subtest Letter Identification Word Identification (Vocab.) Word Attack (Phonetics) Word Comprehension (Analogies) Passage Comprehension Total Reading Score
F
P
1.61 3.10 2.34 3.54 3.10 4.60
.20 .05 .10 .03 .05 .01
Table 2 Duncan Tests of Significances Comparing Hydrocephalics, Letter Reversals and Controls on Reading Measures
Word Identification (Vocab) Hydrocephalics Letter Reversal Controls
51.4 66.8 76.5
A A
38.9 56.3 65.5
A A
47.5 60.5 73.3
A A
42.2 64.7 79.5
B A
B B
Word Comprehension (Analogies) Hydrocephalics Letter Reversal Controls
B B
Passage Comprehension Hydrocephalics Letter Reversal Controls
B B
Total Reading Level Hydrocephalics Letter Reversal Controls
B B
Groups having the same letter are not significantly different from each other.
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of performance. While mean differences were significant for hydrocephalic children and controls, it is important to note that the level of performance of these hydrocephalic children was actually normal. That is, their reading scores were consistently in the high 40 to mid 50 percentile range for normal children (on whom the tests were standarized). Uncomplicated, congenital hydrocephalic children do not show, therefore, any lag in reading proficiency as has been previously reported in hydrocephalic children who have other brain anomalies in addition to hydrocephalus.
Information Processing Results Tactile Task: Hydrocephalic children made significantly more total number of tactile errors, more errors when same hand matching, and more intermanual matching to sample errors than did letter reversal and normal controls (see Table 3). Paired t-tests on mean difference scores between errors made in the right hand or the left hand revealed hydrocephalics made significantly more left hand errors than did controls or letter reversal children. Letter reversal children made significantly more intermanual errors than single hand errors. Qualitative error differences occurred between hydrocephalics and the other two groups. Errors can be of two types: choosing the mirror image of the correct stimulus or choosing a spatially unrelated stimulus. A mirror image index was calculated for each subject. The mirror image index equals the number of mirror image errors divided by the total number of errors. The number of mirror image errors and the mean mirror image index for hydrocephalics was significantly lower than for controls or letter reversals each of the two years. The mirror image index improved to second year from .32 to .66 but was still lower than controls or LRs. Controls and letter reversal children did not differ from one another (see Table 4). Hydrocephalic children were apparently having greater difficulty with the internal representation of the stimulus. Control and LR children, when they made mistakes, apparently had difficulty primarily with the orientation of the tactile stimulus, but not its internal representation. Visual Task: Quantitatively, hydrocephalics made significantly more errors in both the right visual hemifield and the left visual hemifield. The second year of testing, no quantitative differences between groups occurred. Qualitatively, hydrocephalic children differed from controls and LRs. Over half of the children tested in the hydrocephalic, control, and LR groups were unable to take the visual test; the reasons per group differed. Control and LR subjects usually failed to perceive the stimulus. Hydrocephalic children, however, usually failed the perceptual workup at any speed. (see Table 5). Auditory Tasks: Hydrocephalic children made significantly more errors in
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both monaural and dichotic conditions than control children and letter reversal children the first year. The increased errors were in the right ear monaurally, and both right and left ears dichotically (see Table 6). The second year, no mean differences between groups occurred. Second Year Results
Hydrocephalic children were statistically inferior to both letter reversal and normal children, on total reading percentile, but their mean value was within the normal range (54.5 percentile). Tactile information processing deficits still occurred in hydrocephalic children compared to controls. However, letter reversal children did not make more intermanual errors than single hand errors. On the visual task, no quantitative differences between groups occurred. However, qualitative differences between groups still existed. Almost all controls and LRs were able to take the visual test. Approximately 41% of the hydrocephalic children could still not take the visual test; they still failed to perceive the perceptual stimuli. On the auditory task, no mean differences occurred between groups. CONCLUSIONS 1.
2.
3.
Hydrocephalics showed tactile information processing deficits, both quantitatively and qualitatively, both years when compared to controls and letter reversal children. Hydrocephalic children showed consistent qualitative differences in visual information processing than did normal children and letter reversal children both years studied. Hydrocephalic children did not show consistent difference (i.e., both years) in auditory processing of information from letter reversals and control children.
Relation of Information Processing to Reading Skills
To answer the second question, the relationship between primary sensory information processing and reading proficiency, Pearson-r product moment correlations between specific information processing error scores and the individual subtests of the Woodcock Reading Test Battery were analyzed by group. Several interesting significant correlations (p. < .05) emerged the first year in the hydrocephalic group (1) between errors when naming the fixation color in the visual task and some reading tests (word Identification, r = .80; Word Attack r = .85; Word Comprehension r = .75, Passage Comprehension r = .98; total reading percentile r = .95, and
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Language Sciences, Volume 7, Number 1 (1985)
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(2) between visual exposure time and Word Identification test performance (r = .82). For the letter reversal group, several statistically significant correlations resulted. These were all visual information processing error scores. All visual errors scores were sign'.~cantly positively correlated with reading test scores (opposite visual hemifield, same visual hemifield, left visual hemifield errors, right visual hemifield errors and exposure time), except for total visual errors which were negatively correlated only with Letter Identification (r = .46). Controls demonstrated statistically significant positive correlations (1) between many tactile error scores (total errors, same hand matching errors, left hand errors, and right hand errors) and some reading test scores, and (2) between visual error scores of fixation and right visual h.emifield errors. These correlations between information processing errors and reading scores were considered unreliable due to either (1) a failure to reach significance the second year or (2) a sign change (from positive to negative) by the second year of testing. The conclusion drawn from these analyses was that there are no consistent associations between specific tactile, visual, and auditory information processing errors and reading proficiency, either the total reading score or component reading skills, in any of the groups tested. Post Hoe Analyses of Reading Proficiencies The possibility that reading proficiency was related to the level of basic information processing skills only in poor readers was also investigated. The subjects were all pooled, collapsing across groups. Two groups of reading proficiency were then formed. The low proficiency group consisted of those individuals who were at the 25th percentile or lower on their total reading score, a total of 33 children. The high proficiency group consisted of those whose total reading score was at the 75th percentile or greater, a total of 22 children. An analysis of variance was performed on information processing error scores between these two groups. All information processing error scores, tactile, auditory and visual, were significantly higher in the low proficiency group than for high proficiency readers. However, a potentially confounding factor was verbal intelligence. The low and high proficiency groups differed significantly on the Vocabulary Subtest scale scores of the WlSC-R or WPPSI. An analysis of covarianee was, therefore, performed with Vocabulary Subtest scale scores as the covariate. For the first year studied, with (estimated) verbal intelligence partialled out, low proficiency readers made significantly fewer mirror image tactile errors (but not significantly fewer total tactile errors) than did high proficiency readers. Visually, low proficiency readers had faster exposure times. The second year, neither of these findings (tactile or visual information processing error differences) were statistically significant between high and low proficiency readers.
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Summary of Results:
1. 2.
Reading proficiency appears to be normal in uncomplicated, congenital hydrocephalic children. Information processing deficits do not specifically relate to reading proficiencies at this age level.
DISCUSSION The present findings suggest that uncomplicated, congenital hydrocephalic children who suffer no other brain anomaly and who are surgically shunted or who show an arrest of the hydrocephalic process show normal levels of reading competency. These data suggest that previous reports of hydrocephalic children lagging behind in reading competency do not necessarily hold when other brain anomalies are absent. In all likelihood, it is the presence of children with multiple brain lesions which occur in compficated hydrocephalus that accounts for the literature reports of reading lags. We have observed complicated hydrocephalic cases in which reading difficulties are common. For example, we recently studied a 7½ years old hydrocephalic child with an associated right frontal-parietal porencephalic cyst which was present at birth. This child was shunted at age 4½ months and has never had any surgical complications. While she had an average to above average IQ (Verbal IQ = 100, Performance IQ = 121), she had poor reading proficiency. On the Woodcock Reading Mastery Test, her total reading percentile was only at the 24th percentile. Letter Identification was at the 55th percentile, Word Identification at the 6th percentile, Word Attack skills at the 50th percentile, Word Comprehension at the 13th percentile and Passage Completion at the 54th percentile. She made numerous errors on visual and tactile information processing tasks, and a particularly high number of errors in the left visual hemifield. It appears that her early multiple brain lesions affected primarily right cerebral hemisphere functioning and consequently may have lowered her reading proficiency. Secondly, the data from the present study also demonstrated that there is no consistent relationship between errors of visual and tactile information processing and reading competency in these groups of children. This is an interesting f'mding, especially since two of the groups were controls. Literature studies which demonstrate a relationship between reading and information processing levels usually contain one of two sources of methodological problems: (1) they are cross-sectional or (2) they correlate visual processing with reading in groups with reading difficulties. For example, a cross-sectional study of older children with reading problems reveals a positive correlation between poor left hemisphere visual information processing
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and poor reading performance (Pirozzolo and Rayner 1979). Denckla (1982)has stressed the importance of longitudinal research as opposed to cross-sectional sampling in children with proficiency skill problems. She contends that difficulties in proficiency skills may change over time in children with "disorders of attention." These skill difficulties provide chronological "markers" of the attentional problems; they may occur one year, but be replaced the next year with a different proficiency skill deficit. It is possible that the information processing difficulties occurring in hydrocephalics are "chronological markers" of an underlying attentional deficit, and would therefore correlate with reading skill one year, but not the next. If this is the case, then some other skill deficiency such as arithmetic (which we did not measure) would be expected to correlate with information processing difficulties if reading proficiency did not. However, the fact that information processing and reading levels were not related in any of the groups over a two year period, spanning kindergarten to third grade, makes the appearance of a later reading deficit an unlikely event. A second possibility is that the sensory nature of our information processing task was too basic a unit of behavior to correlate with a complex phenomenon, such as reading proficiency. This would suggest the next higher level of information processing, such as difficulties in cross-modal information processing, may correlate better with reading skills (see Barroso 1976). The present data also reveal an important methodological problem when studying reading performances in children: group differences in intelligence level. Post hoc analyses did show that poor readers made significantly more errors in information processing than did good readers; however, poor readers also had lower vocabulary test scores. When vocabulary level was statistically held constant, the differences between the groups on information processing errors were no longer reliably different. Apparently, a general intelligence or verbal problem solving factor may greatly influence performance not only in reading skill but also in the processing of basic sensory information. Research which purports to relate information processing difficulties to reading problems must concomitantly account for the possible confounding effects of intelligence level. An additional interesting question was raised during data analysis. Did either hydrocephalic, LR, or normal children evidence lateralization of linguistic information processing? While the tactile task was not "linguistic" in nature, the visual and auditory tasks used linguistic stimuli (written letters and spoken vowel/ consonant sounds). Data from all three tasks are presented, because the findings are rather consistent. Table 3 shows that hydrocephalic children made significantly more tactile errors than controls or letter reversal children. However, the total number of errors made in the right and left hands was equivalent. Only the total number of errors
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increased as one goes from healthy children to brain dysfunctional children in this age range. The same pattern was seen for the linguistic stimuli in the visual information processing task. Table 5 illustrates the visual data. Again, hydrocephalics made more errors than controls or LR children. Yet the total number of errors was the same in the right and left visual hemifields. In terms of auditory processing, however, all children showed a clear right ear advantage on dichotic listening. That is, under bilateral simultaneous presentation of vowel/consonant sounds, hydrocephalic, letter reversal and normal children were able to more accurately perceive the sounds presented in the right ear compared to the left. This finding is compatible with Kimura (1967) and suggests a right ear-left hemisphere "advantage" in this younger age range. When it comes to processing auditory stimuli, there may not be symmetrical functional capacity of the two cerebral hemispheres. Interestingly, hydrocephalic children were not significantly different in right ear dichotic errors compared to controls and letter reversal children. However, they were significantly impaired in the left ear under dichotic presentation. A strict "sensory impairment" explanation would not fit the data. The present findings are also in agreement with previous reports in the literature which suggest that two cerebral hemispheres are functionally equivalent in processing information up to age 10, at least for tactile and visual information in normal children (Barrso 1976). While hydrocephalic children repeatedly made more errors in visual and tactile information processing, these children as well as letter reversal children and controls showed essentially equivalent performance in processing information in the right versus the left visual field and in processing information in the right versus the left hand. The exception to these findings is seen in the processing of auditory information for vowel-consonant sounds. A clear right ear advantage was observed in our patient groups. These data agree with Kimura's (1967) observation that a right ear-left hemisphere preference for processing auditory linguistic information may well exist before the age of 10. The practical significance of this right ear advantage for reading remains obscure. All three groups of children demonstrated this right ear advantage. Yet, there were clear group differences in terms of level of reading proficiency. It might be argued that hydrocephalic children showed normal reading scores, because they do in fact have lateralization of auditory vowel/consonant perception in the left cerebral hemisphere. Yet, degree of right ear advantage does not seem to be related to level of reading proficiency, at least in this age range. Finally, these data, and others with hydrocephalic children, raise an interesting paradox for those interested in the mind-brain problem. How is it possible to have a congenital disturbance that in all probability influences the developing neurocircui-
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try of the brain (see Zeiner and Prigatano 1982; Rakic 1981) and still retain average reading skills and average vocabulary (see Prigatano et al., in press). Why don't the reading skills of hydrocephalic children reflect the massive compression of brain tissue and neurocircuitry disruption? One answer may be that the developing brain is especially equipped to compensate for early brain lesions. The work of Patricia Goldman-Rakic (1981) eloquently illustrates how the young brain can redistribute neural connections following injury. The neurological literature in children suggests that up to age 10 (at least before the onset of puberty) the brain may be more equipotential in its functional capacity. Perhaps puberty, with its flood of chemical changes in the brain, allows the development of hemispheric specialization of functional capacity..Future research with hydrocephalic children should study linguistic competency in those children who have been successfully managed surgically prior to the age of 10 versus those who have not. Those hydrocephalic children who have repeated problems with their shunt apparatus and/or who experience multiple infections following shunting after hemispheric specialization has occurred may well be the ones who have the greatest linguistic and reading difficulties ( > 10 yrs). Longitudinal research with different subgroups of hydrocephalic children, complicated versus uncomplicated, single shunt versus multiple shunt revisions, hyperverbal versus normal verbal output, will be necessary to resolve these issues. REFERENCES
Badell-Ribera, Angeles, Kenneth Shulman, and Nancy Paddock 1966 "The Relationship of Non-progressive Hydrocephalus to Intellectual Functioning in Children with Spina Bifida Cystica," Pediatrics 37.787-93. Barroso, F. 1980
"Hemispheric Asymmetry of Function in Children," in The Neuropsychology of Language, pp. 157-80. R.W. Riber (ed.), New York: Plenum Press.
Denckla, M. "Developmental Disorders of Learning and Attention," Presented at 1982 the American Psychological Association meeting in Washington, D.C. Diller, Leonard, Nancy Paddock, Angeles Badell-Ribera, and C.A. Swinyard 1966 "Verbal Behavior in Spina Bifida Children," in Comprehensive Care of Children with Spina Biputa Manifesta, pp. 100-6. C.A. Swinyard (ed.), Rehabilitation Monorgraph #31, New York: Institute of Rehabilitation.
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Fleming, C. 1968 "The Verbal Behavior of Hydrocephalic Children," Developmental Medicine in Children's Neurology, Supplement 15.74-82. Goldman-Radic, Patricia S. 1981 "Development and Plasticity of Primate Frontal Association Cortex," in The Organization of the Cerebral Cortex, F.O. Schrnitt et al. (eds.), Cambridge, Massachusetts: MIT Press. Hadenius, A.R., B. Hagber, K. Hyttnas-Bensch, and I. Sjogren 1962 "The Natural Prognosis of Infantile Hydrocephalus," Acta Paediatrics 51.117-23. Ingram, T.T.S. and J.A. Naughton 1962 "Pediatric and Psychological Aspects of Cerebral Palsy Associated with Hydrocephalus," Developmental Medicine in Children's Neurology 4.287-93. Kimura, Doreen 1967 "Functional Asymmetry of the Brain in Dichotic Listening," Cortex 3.163-78. Laurence, K. and S. Coates 1962 "The Natural History of Hydrocephalus," Archives of Disabled Children 37.345-62. Miller, Edgar and L. Sethi 1971 "Tactile Matching in Children with Hydrocephalus," Neuropadiatrie 3.191-94. Noble, J. "Mirror-images and the Forebrain Commissures of the Monkey," 1966 Nature 211.1263-66. Pirozzolo, Francis and K. Rayner 1979 "Central Organization and Reading Disability," Neuropsychologia 17.485-91. Prigatano, George P., Harriet Zeiner, Michael PoUay, and Ralph Kaplan 1983 "Neuropsychologicai Functioning in Hydrocephalic Children with Functional Shunts," Child's Brain 10.112-20. Rakic, Pasko "Developmental Events Leading to Lamminar and Areal Organization 1981 of the Neocortex," in The Organization of the Cerebral Cortex, F.O. Schmitt et al. (eds.), Cambridge, Massachusetts: MIT Press. Spain, B. "Verbal Performance and Ability in Preschool Children with Spina 1974 Sifida," Developmental Medicine in Children's Neurology 16.773-80.
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Swisher, Lawrence P. and E.F. Pinsker 1971 "The Language Characteristics ofHyperverbal Hydrocephalic Children," Developmental Medicine in Children's Neurology 13.7;46-55. Taylor, Edith Meyer 1961 PsychologicalAppraisal of Children with CerebralDefects, Cambridge, Massachusetts: Harvard University Press. Taylor, M. "The Measurement of Functional Communication in Aphasia," 1965 Archives of Physical Medicine 46.101-11. Zeiner, Harriet K. and George P. Prigatano 1982 "Information Processing Deficits in Hydrocephalic and Letter Reversal Children," Neuropsychologia 20.4.483-92. Woodcock, R.W. 1973 Woodcock Reading Mastery Tests Manual. Minnesota: American Guidance Service, Inc.
George P. Prigatano and Harriet K. Zeiner
Presbyterian Hospital University of Oklahoma
ABSTRACT Cross-sectional studies of heterogeneous groups of hydrocephalic children report reading lags of 18 months compared to controls matched for physical disability. This longitudinal study investigated the relationship between the global skill of reading and basic sensory information processing capacities in three homogeneous gzoups of children: 21 children with uncomplicated hydrocephalus; 24 children who made excessive letter reversals (LR), and 30 normal school children. All children had normal range IQ, and were 4-10 years of age. Three information processing tasks were administered once per year for two years: a tactile matching-to-sample, a visual tachistoscopic matching-to-sample task and an auditory dichotic listening task. Woodcock Reading Mastery Tests were given to measure reading proficiency. Hydrocephalics demonstrated a number of consistent information processing deficits when compared to letter reversal and normal school children. Hydrocephalics showed tactile infonnation processing deficits, quantitatively and qualitatively, both years. Hydrocephalic children showed consistent qualitative differences in visual information processing both years. Hydrocephalics did now show consistent differences (i.e., both years) in auditory information processing. Global reading proficiency appeared to be normal both in children with uncomplicated hydrocephalus and letter reversal children with normal range IQ. Some subcomponent reading skills were impaired in hydrocephalics. Several significant correlations were found between information processing errors and reading scores in both hydrocephalics and letter reversal children. However, these correlations were considered unreliable due to either (1) a failure to reach significance the second year or (2) a sign change from positive to negative by the second year of testing. The conclusion was drawn that there were no consistent associations between specific tactile, visual, and auditory information processing deficits and reading proficiency in any of the three groups tested. These results are discussed in light of the importance of longitudinal research with homogeneous groups as opposed to cross-sectional sampling in children with proficiency skill problems.
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INTRODUCTION We have been conducting longitudinal neurobehavioral research with a group of children who suffer from congenital communicating hydrocephalus. In the past, we have described the information processing capacities (Zeiner and Prigatano 1982) and neuropsychological functioning (Prigatano, Zeiner, Pollay, and Kaplan, in press) of these children. The present study attempts to relate the academic skill of reading to basic information processing skills in young children (4-10 years) with shunted congenital hydrocephalus. Before describing the linguistic and reading impairments known to occur in these children, a brief review of the neuropathy and information processing problems associated with hydrocephalus will be discussed. Neuroanatomay of Hydrocephalus Within the cerebral hemispheres lie four major spaces called ventricles. The largest spaces invade the frontal, temporal and parietal-occipital lobes, and are known as the lateral ventricles. The third and fourth ventricles are connected via a hollow pathway known as the cerebral aquaduct. Around and through these ventricular spaces flows cerebrospinal fluid (CSF) in a specified route of circulation. Obstruction of the flow of CSF anywhere throughout the system can cause a buildup of fluid within the ventricles. This produces the condition known as hydrocephalus. Since brain tissue is more compressable than either CSF or the skull, expanding fluid buildup results in thinning of brain mass. The compressive effects of pressure result in thinning of myelin, loss of white matter of the brain, and may eventually include respiratory arrest as intracranial pressure increases. Children with hydrocephalus diagnosed at birth may also suffer from neurocircuitry problems. Migration of cells which later form corticofugal connections begins along and is determined by placement of the ceils on the walls of the lateral ventricles in utero. Thus, fetal hydrocephalus may result in neurocircuitry wiring abnormalities in addition to the compressive effects of raised intracranial pressure (Rakic 1981). Treatment of hydrocephalus consists of placing a mechanical shunt in the lateral ventricles which allows excess CSF to drain via a subcutaneous catheter into the peritoneal cavity. This results in a reduction of ventricle size to within normal limits (or even smaller). Frequently brain tissue re-expands, with myelin sheath deposits increasing in size. Basic Information Processing in Hydrocephalic Children In a previous report (Zeiner and Prigatano 1982) we described the ability of hydrocephalic children to process visual, auditory, and tactile information. This
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work was prompted by the suggestion of Miller and Sethi (1971) that the pressure of CSF resulting from enlarged ventricles could mechanically stretch corpus callosum fibers. Callosal fibers allow transmission of information from one side of the brain to the other. Miller and Sethi believed hydrocephalic children suffered from a "partial" callosal syndrome, i.e., an inefficiency of interhemisphere transfer of information. Since mirror-image errors have also been related to callosal dysfunction in animals (Noble 1966), we compared hydrocephalic children to two groups of controls: normal children, and children who made excessive letter reversals. While the experimental tests used were shown to be sensitive to individuals with known caUosal lesions, the study failed to demonstrate a "partial" callosal sydrome in hydrocephalic children. Their information processing abilities demonstrated numerous intra- as well as interhemispheric information processing difficulties compared to controls. Letter reversal children were often similar to controls, but consistently fell between normals and hydrocephalic children on the various information'processing tasks. Linguistic Functioning in Hydrocephalic Children
A number of observers have reported that some hydrocephalic children talk excessively (Hadenius et al. 1962; Ingram and Naughton 1962; Laurence and Coates 1962) and that their speech is lacking in content (Badell-Ribera, Shulman, and Paddock 1966; Swisher and Pinsker 1971; Spain 1974). Taylor (1961) pointed out that these children do well in repeating stories from memory, but cannot explain the content of the stories. These limitations of language ability are reflected on intelligence tests. They may do well on some verbal tasks, such as picture vocabulary, but fail on verbal tasks which call for reasoning and comprehension. Experimental studies of children with hydrocephalus indicate that they do not talk more than other children of the same age (Fleming 1968; and Diller, Paddock, BadeU-Ribera, and Swinyard 1966), i.e., they are not quantitatively different. Hydrocephallc children differed from controls on qualitative rather than quantitative measures of verbal output on the Children's Apperception Test (Fleming 1968). They made significantly greater number of inappropriate responses, particularly in situations of stress. Taylor (1965) also described qualitative differences in hydrocephalic speech. He found a discrepancy between language produced in a less distracting, formal test situation and language produced in an unstructured setting. In a conversational setting, hyperverbal hydrocephalic children exhibited a profile which reflected the superficiality of their output on the Illinois Test of Psycholinguistic Abilities (ITPA). They earned low scores on the auditory-decoding subtest (understanding what is heard, e.g., "Do apples fly?" and the auditory-vocal association subtests, (relating
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spoken words in a meaningful way, e.g., soup is hot, ice cream is cold. There was no impairment on the auditory.automatic subtest which consists of adding a correct grammatical form to complete a sentence, and is a measure of syntax (Swisher and Pinsker 1971). Swisher and Pinsker's finding of normal grammatical functioning is similar to Spain's result that hyperverbal hydrocephalic children produce below average scores on the Reynell Scale verbal content and comprehension test, but average scores for syntax development. Thus, several studies have found normal grammar and syntax development coupled with below average comprehension performance on verbal tasks. In addition to formal linguistic difficulties, children with congenital hydrocephalus have also been reported to lag behind control groups matched for physical disability by 18 months in reading proficiency in both the United States (DiUer, Baddell-Ribera, and Swinyard 1966) and in Great Britain (Laurence and Coates 1962). In the present study, we attempted to relate reading proficiency with basic visual, auditory, and tactile information processing skills in a subgroup of hydrocephalic children. Reading is a global skill which can be broken down into subcomponent skills, e.g., the ability to identify letters, read vocabulary words, sound out words, the ability to understand words and use them in analogies, and the ability to complete sentences. These are skills which are presumed to be necessary for normal reading proficiency by educators, reading test constructors and researchers in learning disability. We were interested in the relationship between the global skill of reading, the subcomponent skills used to compute global reading proficiency, and basic sensory information processing capacities. The following specific questions were posed: 1. Do children with uncomplicated hydrocephalus show normal reading proficiencies? 2. Is there a relationship between reading proficiency, or a subcomponent of reading proficiency, and information processing difficulties in hydrocephalic, normal, or letter reversal children?
METHOD From a methodological point of view, it is important to make a distinction between complicated (presence of other brain anomalies in addition to hydrocephalus) and uncomplicated communicating hydrocephalus. Many of the complications frequently associated with hydrocephalus (e.g., seizure disorders, meningitis, porencephalic cysts) are themselves known to be associated with cognitive impairments. We were concerned with information processing and academic impairments
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associated with the congenital hydrocephalic process per se, and not with the variety of cognitive impairments which might be due to a combination of both hydrocephalus and frequently occurring brain lesions. Subjects A detailed description of the children studied in this project is available elsewhere (Zeiner and Prigatano 1982; Prigatano et al., in press). For purposes of this report, however, the following facts are pertinent. Twenty-one (21) hydrocephalic children between the ages of 4 and 10 years, with shunted uncomplicated congenital hydrocephalus, and who were judged to have at least low normal intelligence were studied. Thirteen of these children were male, 8 were female. Thirteen were right handed, 6 were left handed, and 2 had mixed handedness. Their mean age was 6.2 years. Twenty-four letter reversal (LR) children, between the ages of 5 to 9 years, without any history of neurological or psychiatric difficulties, and who were judged to have at least low normal intelligence were also studied. These children were referred by their teachers as making excessive letter reversals. These reversal errors occurred in both written and spoken language. Eleven were male, 13 were female, 22 were right handed, 1 was left handed, and 1 had mixed handedness. Their mean age was 6.5 years. Thirty (30) normal elementary school children between the ages of 4 to 10 years, with at least low normal intelligence, were also studied. Fifteen were male and 15 were female. Twenty-six were right handed, 1 was left handed, and 3 had mixed dominance. Apparatus and Tasks: Information Processing Measures Three information processing tasks were used in the initial report: A tactile matching-to-sample task, a visual tachistoscopic matching-to-sample task, and an auditory dichotic listening task. The latter two tasks directly dealt with linguistic information, the first did not. The tactile task required the subject to feel a nail head design hidden from view with one hand. The subject was, then, required to pick out the same tactile stimulus from a 6 stimulus array (also hidden from view) with either the same hand or the opposite hand. Right hand trials first versus left hand trials first were counterbalanced; sixteen trials were given in all. Subjects were asked not to name the stimuli aloud, but to simply identify the same stimlus they had previously touched. The visual tasks required the subject to centrally fixate on a tachistoscopically presented colored dot which the subject named. A letter stimlus (b, d, q, p, and E) was then presented tachistoscopically to either the temporal right or temporal left
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visual hemifield for a very brief period (60-125 msec., determined by workup prior to the visual testing). A central fLxation colored dot was again given. A second visual stimulus was, then, given to either the same visual hemifield as the first stimulus or to the opposite visual hemifield. The second stimulus was either the same as the first stimulus or was a mirror image reversal. The subject's task was (1) to name the colored dot (to insure central fLxation) and (2) to say whether the two successive stimuli were the "same" or "different." Subjects were asked not to name the letters. Visual hemffields for both initial and second stimulus presentation, letter presented, number of reversals, and responses (i.e. "same or different") were counterbalanced. Forty-eight trials were presented. The auditory task was a dichotic listening paradigm. Consonant/vowel sounds (ga, ba, da, ka, ta) were given monaurally via earphones. The subject was required to say the sound aloud. Each ear was tested separately. Then, two different consonant/vowel sounds were presented simultaneously, one in the right ear and the other in the left ear. The subject's task was to name both sounds given. The earphones were then reversed, and the entire test, both monaural and dichotic presentations, was repeated. Right ear first versus left ear first in the monaural condition was counterbalanced. A total of thirty-six monaural trials was given in each ear. Seventy-two dichotic trials were presented. These three tasks are discribed in more detail in Zeiner and Prigatano, (1982). All three information processing tasks were repeated the second year.
Reading Proficiency Measures: Woodcock Reading Mastery Tests The Woodcock Reading Mastery Tests, Form A, were given the first year, Form B the second year. The Woodcock Reading Mastery Tests consist of a battery of five individually administered reading tests for use from kindergarten through grade 12. The five tests were: letter identification (LID), word identification (Word ID), word attack, (phonics), word comprehension (analogies), and passage comprehension. The component tests were, then, used to compute a total Reading Percentile Score. The Letter Identification Test contained 45 items which measure the subject's ability to name letters of the English alphabet. Test items include a variety of common and, in some cases, uncommon styles of type. The letter items are arranged in order of difficulty within the test and the subject's task is to name each letter. Children who are at the beginning of the first grade are generally able to name several letters, particularly those involving upper- and lower-case Roman styles. For more details of this subtest and the ones below, please see the Woodcock Reading Mastery
Test Manual.
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The Word Identification Test consisted of a set of 150 words ranging in difficulty from the first words presented in a typical beginning reading program (e.g., the, go, and) to words of above average difficulty for superior students in the twelfth grade (e.g., facetious, beatitude, picayune). The Word Attack Test contained 50 items which measure the subject's ability to identify nonsense words via phonetics. At the lower end of the test the nonsense words were simple consonant/vowel combinations such as "dee" and "lat." Multisyllabic words such as "ipdan" and "depmonlel" were presented at the upper end of the test. Represented within the set of nonsense words were most consonant/ vowel sounds, common prefixes and suffixes, and frequently appearing irregular spellings of vowels and consonants (e.g. "ph" for "f," "igh" for long 'T'). The Word Comprehension Test contained 70 items designed to measure a subject's knowledge of word meanings. An analogy format was used. The subject's task was to read the first pair of words in an analogy, then read the first word of the second pair and say a word which would complete the analogy. (e.g., bird-fly,
fish-). Passage Comprehension contained 85 items constructed with a modified close procedure. The subject's task was to silently read a passage which had a word missing and tell the examiner an appropriate word to go in the blank space. Results from the five tests in the battery were combined to provide a composite of overall reading skill. Percentile scores for each test were based on national norms standarized on grade levels divided by month.
Statistical Analyses The data were analyzed with analysis of variance, Duncan Multiple Range Tests, paired t-test, Pearson-r product moment correlations and, when appropriate, analysis of covariance. RESULTS Reading Proficiency in Hydrocephalic Children The initial question posed was whether or not hydrocephalic children demonstrated impaired reading skills. Table 1 summarizes the ANOVA F values and probabilities for each of the Woodcock Reading Mastery Tests for the three groups of children studied. Significant differences were obtained in word recognition (vocabulary), word comprehension (analogies), passage comprehension, and total reading scores during the first year of testing. Table 2 illustrates that hydrocephalic children were consistently reliably different from normal controls, but were equal to letter reversal children. Also, letter reversal children were not reliably different from controls, but were between hydrocephalic and control groups in their level
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Table I Woodcock Reading Master Scores: Hydrocephalics vs LR vs Controls ANOVA Results
Subtest Letter Identification Word Identification (Vocab.) Word Attack (Phonetics) Word Comprehension (Analogies) Passage Comprehension Total Reading Score
F
P
1.61 3.10 2.34 3.54 3.10 4.60
.20 .05 .10 .03 .05 .01
Table 2 Duncan Tests of Significances Comparing Hydrocephalics, Letter Reversals and Controls on Reading Measures
Word Identification (Vocab) Hydrocephalics Letter Reversal Controls
51.4 66.8 76.5
A A
38.9 56.3 65.5
A A
47.5 60.5 73.3
A A
42.2 64.7 79.5
B A
B B
Word Comprehension (Analogies) Hydrocephalics Letter Reversal Controls
B B
Passage Comprehension Hydrocephalics Letter Reversal Controls
B B
Total Reading Level Hydrocephalics Letter Reversal Controls
B B
Groups having the same letter are not significantly different from each other.
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of performance. While mean differences were significant for hydrocephalic children and controls, it is important to note that the level of performance of these hydrocephalic children was actually normal. That is, their reading scores were consistently in the high 40 to mid 50 percentile range for normal children (on whom the tests were standarized). Uncomplicated, congenital hydrocephalic children do not show, therefore, any lag in reading proficiency as has been previously reported in hydrocephalic children who have other brain anomalies in addition to hydrocephalus.
Information Processing Results Tactile Task: Hydrocephalic children made significantly more total number of tactile errors, more errors when same hand matching, and more intermanual matching to sample errors than did letter reversal and normal controls (see Table 3). Paired t-tests on mean difference scores between errors made in the right hand or the left hand revealed hydrocephalics made significantly more left hand errors than did controls or letter reversal children. Letter reversal children made significantly more intermanual errors than single hand errors. Qualitative error differences occurred between hydrocephalics and the other two groups. Errors can be of two types: choosing the mirror image of the correct stimulus or choosing a spatially unrelated stimulus. A mirror image index was calculated for each subject. The mirror image index equals the number of mirror image errors divided by the total number of errors. The number of mirror image errors and the mean mirror image index for hydrocephalics was significantly lower than for controls or letter reversals each of the two years. The mirror image index improved to second year from .32 to .66 but was still lower than controls or LRs. Controls and letter reversal children did not differ from one another (see Table 4). Hydrocephalic children were apparently having greater difficulty with the internal representation of the stimulus. Control and LR children, when they made mistakes, apparently had difficulty primarily with the orientation of the tactile stimulus, but not its internal representation. Visual Task: Quantitatively, hydrocephalics made significantly more errors in both the right visual hemifield and the left visual hemifield. The second year of testing, no quantitative differences between groups occurred. Qualitatively, hydrocephalic children differed from controls and LRs. Over half of the children tested in the hydrocephalic, control, and LR groups were unable to take the visual test; the reasons per group differed. Control and LR subjects usually failed to perceive the stimulus. Hydrocephalic children, however, usually failed the perceptual workup at any speed. (see Table 5). Auditory Tasks: Hydrocephalic children made significantly more errors in
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both monaural and dichotic conditions than control children and letter reversal children the first year. The increased errors were in the right ear monaurally, and both right and left ears dichotically (see Table 6). The second year, no mean differences between groups occurred. Second Year Results
Hydrocephalic children were statistically inferior to both letter reversal and normal children, on total reading percentile, but their mean value was within the normal range (54.5 percentile). Tactile information processing deficits still occurred in hydrocephalic children compared to controls. However, letter reversal children did not make more intermanual errors than single hand errors. On the visual task, no quantitative differences between groups occurred. However, qualitative differences between groups still existed. Almost all controls and LRs were able to take the visual test. Approximately 41% of the hydrocephalic children could still not take the visual test; they still failed to perceive the perceptual stimuli. On the auditory task, no mean differences occurred between groups. CONCLUSIONS 1.
2.
3.
Hydrocephalics showed tactile information processing deficits, both quantitatively and qualitatively, both years when compared to controls and letter reversal children. Hydrocephalic children showed consistent qualitative differences in visual information processing than did normal children and letter reversal children both years studied. Hydrocephalic children did not show consistent difference (i.e., both years) in auditory processing of information from letter reversals and control children.
Relation of Information Processing to Reading Skills
To answer the second question, the relationship between primary sensory information processing and reading proficiency, Pearson-r product moment correlations between specific information processing error scores and the individual subtests of the Woodcock Reading Test Battery were analyzed by group. Several interesting significant correlations (p. < .05) emerged the first year in the hydrocephalic group (1) between errors when naming the fixation color in the visual task and some reading tests (word Identification, r = .80; Word Attack r = .85; Word Comprehension r = .75, Passage Comprehension r = .98; total reading percentile r = .95, and
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Language Sciences, Volume 7, Number 1 (1985)
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(2) between visual exposure time and Word Identification test performance (r = .82). For the letter reversal group, several statistically significant correlations resulted. These were all visual information processing error scores. All visual errors scores were sign'.~cantly positively correlated with reading test scores (opposite visual hemifield, same visual hemifield, left visual hemifield errors, right visual hemifield errors and exposure time), except for total visual errors which were negatively correlated only with Letter Identification (r = .46). Controls demonstrated statistically significant positive correlations (1) between many tactile error scores (total errors, same hand matching errors, left hand errors, and right hand errors) and some reading test scores, and (2) between visual error scores of fixation and right visual h.emifield errors. These correlations between information processing errors and reading scores were considered unreliable due to either (1) a failure to reach significance the second year or (2) a sign change (from positive to negative) by the second year of testing. The conclusion drawn from these analyses was that there are no consistent associations between specific tactile, visual, and auditory information processing errors and reading proficiency, either the total reading score or component reading skills, in any of the groups tested. Post Hoe Analyses of Reading Proficiencies The possibility that reading proficiency was related to the level of basic information processing skills only in poor readers was also investigated. The subjects were all pooled, collapsing across groups. Two groups of reading proficiency were then formed. The low proficiency group consisted of those individuals who were at the 25th percentile or lower on their total reading score, a total of 33 children. The high proficiency group consisted of those whose total reading score was at the 75th percentile or greater, a total of 22 children. An analysis of variance was performed on information processing error scores between these two groups. All information processing error scores, tactile, auditory and visual, were significantly higher in the low proficiency group than for high proficiency readers. However, a potentially confounding factor was verbal intelligence. The low and high proficiency groups differed significantly on the Vocabulary Subtest scale scores of the WlSC-R or WPPSI. An analysis of covarianee was, therefore, performed with Vocabulary Subtest scale scores as the covariate. For the first year studied, with (estimated) verbal intelligence partialled out, low proficiency readers made significantly fewer mirror image tactile errors (but not significantly fewer total tactile errors) than did high proficiency readers. Visually, low proficiency readers had faster exposure times. The second year, neither of these findings (tactile or visual information processing error differences) were statistically significant between high and low proficiency readers.
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Summary of Results:
1. 2.
Reading proficiency appears to be normal in uncomplicated, congenital hydrocephalic children. Information processing deficits do not specifically relate to reading proficiencies at this age level.
DISCUSSION The present findings suggest that uncomplicated, congenital hydrocephalic children who suffer no other brain anomaly and who are surgically shunted or who show an arrest of the hydrocephalic process show normal levels of reading competency. These data suggest that previous reports of hydrocephalic children lagging behind in reading competency do not necessarily hold when other brain anomalies are absent. In all likelihood, it is the presence of children with multiple brain lesions which occur in compficated hydrocephalus that accounts for the literature reports of reading lags. We have observed complicated hydrocephalic cases in which reading difficulties are common. For example, we recently studied a 7½ years old hydrocephalic child with an associated right frontal-parietal porencephalic cyst which was present at birth. This child was shunted at age 4½ months and has never had any surgical complications. While she had an average to above average IQ (Verbal IQ = 100, Performance IQ = 121), she had poor reading proficiency. On the Woodcock Reading Mastery Test, her total reading percentile was only at the 24th percentile. Letter Identification was at the 55th percentile, Word Identification at the 6th percentile, Word Attack skills at the 50th percentile, Word Comprehension at the 13th percentile and Passage Completion at the 54th percentile. She made numerous errors on visual and tactile information processing tasks, and a particularly high number of errors in the left visual hemifield. It appears that her early multiple brain lesions affected primarily right cerebral hemisphere functioning and consequently may have lowered her reading proficiency. Secondly, the data from the present study also demonstrated that there is no consistent relationship between errors of visual and tactile information processing and reading competency in these groups of children. This is an interesting f'mding, especially since two of the groups were controls. Literature studies which demonstrate a relationship between reading and information processing levels usually contain one of two sources of methodological problems: (1) they are cross-sectional or (2) they correlate visual processing with reading in groups with reading difficulties. For example, a cross-sectional study of older children with reading problems reveals a positive correlation between poor left hemisphere visual information processing
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and poor reading performance (Pirozzolo and Rayner 1979). Denckla (1982)has stressed the importance of longitudinal research as opposed to cross-sectional sampling in children with proficiency skill problems. She contends that difficulties in proficiency skills may change over time in children with "disorders of attention." These skill difficulties provide chronological "markers" of the attentional problems; they may occur one year, but be replaced the next year with a different proficiency skill deficit. It is possible that the information processing difficulties occurring in hydrocephalics are "chronological markers" of an underlying attentional deficit, and would therefore correlate with reading skill one year, but not the next. If this is the case, then some other skill deficiency such as arithmetic (which we did not measure) would be expected to correlate with information processing difficulties if reading proficiency did not. However, the fact that information processing and reading levels were not related in any of the groups over a two year period, spanning kindergarten to third grade, makes the appearance of a later reading deficit an unlikely event. A second possibility is that the sensory nature of our information processing task was too basic a unit of behavior to correlate with a complex phenomenon, such as reading proficiency. This would suggest the next higher level of information processing, such as difficulties in cross-modal information processing, may correlate better with reading skills (see Barroso 1976). The present data also reveal an important methodological problem when studying reading performances in children: group differences in intelligence level. Post hoc analyses did show that poor readers made significantly more errors in information processing than did good readers; however, poor readers also had lower vocabulary test scores. When vocabulary level was statistically held constant, the differences between the groups on information processing errors were no longer reliably different. Apparently, a general intelligence or verbal problem solving factor may greatly influence performance not only in reading skill but also in the processing of basic sensory information. Research which purports to relate information processing difficulties to reading problems must concomitantly account for the possible confounding effects of intelligence level. An additional interesting question was raised during data analysis. Did either hydrocephalic, LR, or normal children evidence lateralization of linguistic information processing? While the tactile task was not "linguistic" in nature, the visual and auditory tasks used linguistic stimuli (written letters and spoken vowel/ consonant sounds). Data from all three tasks are presented, because the findings are rather consistent. Table 3 shows that hydrocephalic children made significantly more tactile errors than controls or letter reversal children. However, the total number of errors made in the right and left hands was equivalent. Only the total number of errors
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increased as one goes from healthy children to brain dysfunctional children in this age range. The same pattern was seen for the linguistic stimuli in the visual information processing task. Table 5 illustrates the visual data. Again, hydrocephalics made more errors than controls or LR children. Yet the total number of errors was the same in the right and left visual hemifields. In terms of auditory processing, however, all children showed a clear right ear advantage on dichotic listening. That is, under bilateral simultaneous presentation of vowel/consonant sounds, hydrocephalic, letter reversal and normal children were able to more accurately perceive the sounds presented in the right ear compared to the left. This finding is compatible with Kimura (1967) and suggests a right ear-left hemisphere "advantage" in this younger age range. When it comes to processing auditory stimuli, there may not be symmetrical functional capacity of the two cerebral hemispheres. Interestingly, hydrocephalic children were not significantly different in right ear dichotic errors compared to controls and letter reversal children. However, they were significantly impaired in the left ear under dichotic presentation. A strict "sensory impairment" explanation would not fit the data. The present findings are also in agreement with previous reports in the literature which suggest that two cerebral hemispheres are functionally equivalent in processing information up to age 10, at least for tactile and visual information in normal children (Barrso 1976). While hydrocephalic children repeatedly made more errors in visual and tactile information processing, these children as well as letter reversal children and controls showed essentially equivalent performance in processing information in the right versus the left visual field and in processing information in the right versus the left hand. The exception to these findings is seen in the processing of auditory information for vowel-consonant sounds. A clear right ear advantage was observed in our patient groups. These data agree with Kimura's (1967) observation that a right ear-left hemisphere preference for processing auditory linguistic information may well exist before the age of 10. The practical significance of this right ear advantage for reading remains obscure. All three groups of children demonstrated this right ear advantage. Yet, there were clear group differences in terms of level of reading proficiency. It might be argued that hydrocephalic children showed normal reading scores, because they do in fact have lateralization of auditory vowel/consonant perception in the left cerebral hemisphere. Yet, degree of right ear advantage does not seem to be related to level of reading proficiency, at least in this age range. Finally, these data, and others with hydrocephalic children, raise an interesting paradox for those interested in the mind-brain problem. How is it possible to have a congenital disturbance that in all probability influences the developing neurocircui-
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try of the brain (see Zeiner and Prigatano 1982; Rakic 1981) and still retain average reading skills and average vocabulary (see Prigatano et al., in press). Why don't the reading skills of hydrocephalic children reflect the massive compression of brain tissue and neurocircuitry disruption? One answer may be that the developing brain is especially equipped to compensate for early brain lesions. The work of Patricia Goldman-Rakic (1981) eloquently illustrates how the young brain can redistribute neural connections following injury. The neurological literature in children suggests that up to age 10 (at least before the onset of puberty) the brain may be more equipotential in its functional capacity. Perhaps puberty, with its flood of chemical changes in the brain, allows the development of hemispheric specialization of functional capacity..Future research with hydrocephalic children should study linguistic competency in those children who have been successfully managed surgically prior to the age of 10 versus those who have not. Those hydrocephalic children who have repeated problems with their shunt apparatus and/or who experience multiple infections following shunting after hemispheric specialization has occurred may well be the ones who have the greatest linguistic and reading difficulties ( > 10 yrs). Longitudinal research with different subgroups of hydrocephalic children, complicated versus uncomplicated, single shunt versus multiple shunt revisions, hyperverbal versus normal verbal output, will be necessary to resolve these issues. REFERENCES
Badell-Ribera, Angeles, Kenneth Shulman, and Nancy Paddock 1966 "The Relationship of Non-progressive Hydrocephalus to Intellectual Functioning in Children with Spina Bifida Cystica," Pediatrics 37.787-93. Barroso, F. 1980
"Hemispheric Asymmetry of Function in Children," in The Neuropsychology of Language, pp. 157-80. R.W. Riber (ed.), New York: Plenum Press.
Denckla, M. "Developmental Disorders of Learning and Attention," Presented at 1982 the American Psychological Association meeting in Washington, D.C. Diller, Leonard, Nancy Paddock, Angeles Badell-Ribera, and C.A. Swinyard 1966 "Verbal Behavior in Spina Bifida Children," in Comprehensive Care of Children with Spina Biputa Manifesta, pp. 100-6. C.A. Swinyard (ed.), Rehabilitation Monorgraph #31, New York: Institute of Rehabilitation.
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Fleming, C. 1968 "The Verbal Behavior of Hydrocephalic Children," Developmental Medicine in Children's Neurology, Supplement 15.74-82. Goldman-Radic, Patricia S. 1981 "Development and Plasticity of Primate Frontal Association Cortex," in The Organization of the Cerebral Cortex, F.O. Schrnitt et al. (eds.), Cambridge, Massachusetts: MIT Press. Hadenius, A.R., B. Hagber, K. Hyttnas-Bensch, and I. Sjogren 1962 "The Natural Prognosis of Infantile Hydrocephalus," Acta Paediatrics 51.117-23. Ingram, T.T.S. and J.A. Naughton 1962 "Pediatric and Psychological Aspects of Cerebral Palsy Associated with Hydrocephalus," Developmental Medicine in Children's Neurology 4.287-93. Kimura, Doreen 1967 "Functional Asymmetry of the Brain in Dichotic Listening," Cortex 3.163-78. Laurence, K. and S. Coates 1962 "The Natural History of Hydrocephalus," Archives of Disabled Children 37.345-62. Miller, Edgar and L. Sethi 1971 "Tactile Matching in Children with Hydrocephalus," Neuropadiatrie 3.191-94. Noble, J. "Mirror-images and the Forebrain Commissures of the Monkey," 1966 Nature 211.1263-66. Pirozzolo, Francis and K. Rayner 1979 "Central Organization and Reading Disability," Neuropsychologia 17.485-91. Prigatano, George P., Harriet Zeiner, Michael PoUay, and Ralph Kaplan 1983 "Neuropsychologicai Functioning in Hydrocephalic Children with Functional Shunts," Child's Brain 10.112-20. Rakic, Pasko "Developmental Events Leading to Lamminar and Areal Organization 1981 of the Neocortex," in The Organization of the Cerebral Cortex, F.O. Schmitt et al. (eds.), Cambridge, Massachusetts: MIT Press. Spain, B. "Verbal Performance and Ability in Preschool Children with Spina 1974 Sifida," Developmental Medicine in Children's Neurology 16.773-80.
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Swisher, Lawrence P. and E.F. Pinsker 1971 "The Language Characteristics ofHyperverbal Hydrocephalic Children," Developmental Medicine in Children's Neurology 13.7;46-55. Taylor, Edith Meyer 1961 PsychologicalAppraisal of Children with CerebralDefects, Cambridge, Massachusetts: Harvard University Press. Taylor, M. "The Measurement of Functional Communication in Aphasia," 1965 Archives of Physical Medicine 46.101-11. Zeiner, Harriet K. and George P. Prigatano 1982 "Information Processing Deficits in Hydrocephalic and Letter Reversal Children," Neuropsychologia 20.4.483-92. Woodcock, R.W. 1973 Woodcock Reading Mastery Tests Manual. Minnesota: American Guidance Service, Inc.