Handbook of psychology volume 7 educational psychology
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- Assessment of Learning Disabilities 475
- ASSESSMENT OF LEARNING DISABILITIES
- The Measurement of Achievement
- Types of Tests
- Assessment of Learning Disabilities 477
474 Learning Disabilities deficits that differentiate them from children with at least reading deficits as defined by depressed scores on the Reading subtest on the WRAT. The cognitive and neuropsycholog- ical profiles of children identified as specific arithmetic- disabled are also different from those of normally achieving children. Evidence (Fletcher, 1985b; Siegel & Linder, 1984; Siegel & Ryan, 1984, 1988, 1989a, 1989b) suggests that those chil- dren meeting the criteria of the specific arithmetic-disabled subtype have deficits in short-term and working memory that are dependent on the type of stimulus and the aspect of mem- ory assessed. Specifically, Siegel and Linder (1984), in a study of the role of phonemic coding in short-term memory, compared three groups of children—one with reading dis- abilities (as defined by scores on the WRAT Reading subtest of equal to or below the 25th percentile and no cutoff on the other two WRAT subtests), a second with arithmetic disabili- ties (as defined by scores on the WRAT Arithmetic subtest of equal to or above the 30th percentile), and a normally achiev- ing group (as defined by scores of greater than or equal to the 30th percentile on all three WRAT subtests). The children, aged 7–13, were administered a series of tasks that involved the visual or auditory presentation of rhyming and non- rhyming letters and either an oral or written response. Pat- terns and levels of performance were compared statistically across three age groups (i.e., 7–8, 9–11, 12–13) and between each subtype and normally achieving children. Due to statis- tical problems, noncomparable age distributions, and small sample sizes, it was not possible to compare across subtypes. Results indicated that both older disabled groups—like their normal counterparts—had significantly poorer recall of rhyming as opposed to nonrhyming letters (except for the oldest—12–13 years—arithmetic-disabled group, in which the authors suggest that the children may be functioning at the upper limit of their visual short-term memory). For stimuli presented visually, the overall performance levels of both LD groups were significantly lower than those of the normally achieving group. For the auditory stimuli, only the reading- disabled group differed significantly from the normally achieving peers. Fletcher (1985b) found differences in memory tasks between LD groups as defined by WRAT scores. He compared four groups of LD children (a reading-spelling- disabled group, a reading-spelling-arithmetic-disabled group, a spelling-arithmetic-disabled group, and an arithmetic- disabled group) and a normally achieving group of children on storage and retrieval aspects of memory for verbal and nonverbal stimuli. He found that relative to the normally achieving controls, both the arithmetic and the arithmetic- spelling-disabled subgroups had significantly lower storage and retrieval scores on the nonverbal task but did not differ from each other; the reading-spelling subgroup differed only on retrieval scores on the verbal task; and the reading- spelling-arithmetic subgroup differed on the retrieval scores on the verbal task and storage and retrieval scores on the non- verbal task. As with Siegel and Linder (1984), the differences between subgroups depended on the type of stimulus (verbal vs. nonverbal) and the aspect of memory (storage or re- trieval) being assessed. Siegel and Ryan (1988) also compared reading-disabled (as defined by WRAT subtest scores), specific arithmetic- disabled (as defined by WRAT subtest scores), and normally achieving children on a variety of skills involving grammati- cal sensitivity, phonology, and short-term memory. In general, it was found that older specific arithmetic-disabled children performed in a manner similar to that of the nor- mally achieving group in grammatical sensitivity and pho- nological tasks. Some exceptions were found in that the arithmetic-disabled children in the 7–10 age group performed more poorly on a sentence repetition task; this difficulty was attributed to the short-term memory component of the task. Additionally, this age group performed more poorly than did normally achieving children on the nonword spelling sec- tions (a writing task) of the phonics task. However, in tasks that measure short-term memory (phonological coding), the specific arithmetic-disabled group performed in a manner similar to that of the reading-disabled group and significantly more poorly than did the normally achieving group. The au- thors conclude that although both of the two disabled groups (compared with normally achieving children) have deficits in short-term memory, only the reading-disabled group had deficits in tasks said to represent a language disorder. Siegel and Ryan (1989a) examined the same groups, using two working memory tasks—one involving sentences and the other involving counting. Again, the disabled groups differed from each other on the types of memory deficits observed. The reading-disabled group differed from the normally achieving children on both tasks, whereas the arithmetic-disabled chil- dren differed from their normally achieving peers only on the counting task. It appears from the research (Fletcher, 1985b; Siegel & Linder, 1984; Siegel & Ryan, 1988, 1989a, 1989b) that although both subtypes of LD children have deficits in short-term and working memory, problems in children with reading deficits are more generalized and involve both verbal and nonverbal aspects of memory, whereas those in children with arithmetic deficits and normal or above-normal reading are more limited to visual, nonverbal, and numerical material. Evidence from a number of sources (Fletcher, 1985b; Rourke & Finlayson, 1978; Share, Moffitt, & Silva, 1988;
Assessment of Learning Disabilities 475 Siegel & Feldman, 1983; Spellacy & Peter, 1978; Webster, 1979) indicates that specific arithmetic-disabled children (as defined by deficient scores on the WRAT Arithmetic subtest and the age-appropriate scores on the WRAT Reading and Spelling subtests—Group 3) have age-appropriate auditory-perceptual and verbal abilities but are deficient on measures of visual-perception and visuospatial abilities. However, reading-disabled children (as defined by being relatively proficient at arithmetic as compared with their WRAT Reading and Spelling subtest scores—Group 2) have age-appropriate visual-perception and visuospatial abilities but are deficient on measures of auditory-perceptual and verbal abilities (Rourke & Finlayson, 1978). Also, Group 3 (arithmetic-disabled) children exhibit difficulty in tasks such as the Halstead Category Test, which require higher order visuospatial analysis and visual-perceptual organization (Strang & Rourke, 1983b). They also appear to exhibit deficits in measures of psychomotor abilities and on tests such as the Tactile Performance Tests (Reitan & Davison, 1974), the Grooved Pegboard Test, and the Maze Test designed to identify tactile-perceptual impairment (Rourke & Strang, 1978; Siegel & Feldman, 1983; Spellacy & Peter, 1978). On the other hand, Rourke and Strang (1978) and Strang and Rourke (1983) found that Group 2 children (relatively profi- cient in arithmetic, compared with their reading and spelling) are proficient at these tasks. In addition, Rourke and Strang (1978) claim that the arith- metic subgroup (Group 3) exhibited normal right-hand per- formance but impaired left-hand performance—the exact opposite of the Group 2 children, who had impaired right- hand performance but normal left-hand performance. Strang and Rourke (1983a, 1983b) suggest that the arithmetic- disabled subgroup has deficiencies in nonverbal concept- formation compared
with other
disabled subgroups. Specifically, when the types of errors made of the Arithmetic subtest of the WRAT were analyzed, it was found that the spe- cific arithmetic subtype tended to make a larger number of er- rors, make a greater variety of errors, and attempted to answer questions without an apparent understanding of the strategies needed to solve the problems (Strang & Rourke, 1985a, 1985b). This error pattern was not found in children with read- ing disabilities (Group 2). As with the research with memory deficits cited earlier, Rourke and Finlayson (1978), Rourke and Strang (1978), and Strang and Rourke (1983a, 1983b) suggest that the character- istics described are different from those of other learning- disabled students (who showed deficits on all the WRAT subtests, Group 1, or just on the reading and spelling subtests compared with the arithmetic subtest, Group 2). This finding has led Rourke et al. (Rourke, 1982, 1983, 1985, 1987; Rourke & Finlayson, 1978; Rourke & Fisk, 1988) to hypothesize that those children with arithmetic deficits belong to the larger nonverbal LD group with right-hemisphere processing prob- lems, whereas those children with deficits in reading as well as arithmetic belong to the larger linguistic learning-disabled group with left-hemisphere processing problems. Clearly, however, children who only have severe deficits in arithmetic can be differentiated from children with reading difficulties and from normally achieving children on cognitive and neuro- psychological profiles. In light of the previously described controversy and research findings, the use of specificity assumptions in the definition of learning disabilities is questionable; this is true regardless of whether one refers to domain specificity (the limitation of the disability to one or two cognitive areas) or population specificity (failure to use subtypes). ASSESSMENT OF LEARNING DISABILITIES Determining who is learning disabled requires careful and sys- tematic assessment. The three following questions address the assessment of learning disabilities: (a) How should achieve- ment be measured; (b) which tests should be used; and (c) what cutoff scores should be used to identify a learning disability? The Measurement of Achievement The arguments about the definition of learning disability center on the determination of whether an individual meets specific criteria for the diagnosis of a disability. First of all, to measure whether there are significant difficulties, one must use a systematic assessment of these academic areas; standardized (norm-referenced) tests appear to be the best way to do this. Why use norm referenced tests? The answer is simple: Those making the assessment want to compare an individual with others of the same age and know whether that person has a significant problem. A standardized test is the best way to accomplish this task. Nonstandardized as- sessments can be used, but they do not provide normative information that can be used for the purposes of comparison. With a nonstandardized or informal assessment, it is impos- sible to know whether an individual has made the number and type of errors that are typical of his or her age group and therefore are normal and expected, or whether the errors are atypical and unexpected and indicative of a problem. Nonstandardized tests may play an important role (to be discussed later), but the core assessment should use stan- dardized tests. However, nonstandardized assessments do have a role in the evaluation of writing; this role is discussed later in the chapter. 476 Learning Disabilities To assess learning disabilities, there are several types of tests that should be used. Specifically, an assessment of an individual for the possibility of a reading disability should in- clude a measure of word-recognition skills. Word recognition is one of the critical building blocks in gaining meaning from print, and it is important to know whether these basic skills in this area are significantly below average (Stanovich, 1982). An assessment should include a reading test that involves the reading of what are called pseudowords—pronounceable combinations of English letters that can be sounded out with the basic rules of grapheme-phoneme correspondences. This type of test assesses the awareness of the phonological as- pects of a language that is the key to decoding words in an alphabetic language such as English. Difficulties with these phonological skills are the basis of a reading disability (e.g., Bruck, 1990; Felton et al., 1990; Shafrir & Siegel, 1994a; Siegel & Ryan, 1988). A test of text reading—specifically, a reading comprehension test—should be included. Obviously, the measurement of text reading skills is particularly impor- tant to measure what individuals remember and understand from what they have read. There should be a test of spelling involving the dictation of words; this parallels the type of spelling required in writ- ing in the academic setting. There should be a test of computational arithmetic skills to determine what the individual understands about the funda- mental arithmetic operations. An assessment of mathematical problem-solving skills should be included. There should also be an assessment of writing skills; this type of assessment is quite difficult for a variety of reasons. The time involved to allow someone to write may be extensive because one must allow time for planning as well as for the actual writing. Also, many individuals have learned to use a computer and prefer to write using a computer. Therefore, a proper assessment of writing might use a computer, which may not be feasible in most assessment contexts. It may be acceptable to ask the individual to bring in a sample of his or her writing, but some type of brief assessment in the context of the assessment is useful. The scoring of these written products is subjective and there does not appear to be agreement on what constitutes a widely accepted scoring system. However, Berninger (1994) has proposed a system that appears to have potential to consistently evaluate writing. She suggests six di- mensions to evaluate writing: (a) handwriting quality (legibil- ity), (b) handwriting fluency (number of words copied within time limits), (c) spelling single words from dictation (on stan- dardized lists of increasing difficulty), (d) spelling in compo- sition (percentage of correctly spelled words), (e) composition fluency (number of words produced within time limits), and (f) composition quality (content and organization of para- graph construction). Identification of whether there is a learning disability should use a simple system. Brief tests of word recognition, decoding (pseudoword reading), reading comprehension, spelling, writing, and computational arithmetic and mathe- matical problem solving will detect most (if not all) of the learning disabilities. A low score on any of these tests is a danger signal. More detailed testing can then be conducted, but any testing should be related to remediation and not used without consideration of what new and useful information is provided by the test and whether it is really necessary—a point that is discussed in detail later in this chapter.
There is considerable confusion in the field about how to measure achievement. Attempts at defining and studying learning disabilities suffer from a common fallacy of assum- ing that all tests that have the same label (e.g., intelligence test, reading test) measure the same skill (Siegel & Heaven, 1986; Siegel et al., 1985). When one considers the area of achievement tests, the labeling fallacy becomes even clearer. There appears to be almost an infinite variety of ways to mea- sure reading, spelling, and arithmetic. The choice of which tests to use can determine whether a disability will be found. Consider the case of measuring reading achievement. There are four types of material that are typically found in reading tests: (a) pseudowords, (b) single words, (c) sen- tences, and (d) paragraphs. For the reading of pseudowords, the individual is asked to read a set of pronounceable combi- nations of letters that test the understanding of the relation- ship between letters or groups of letters and their sounds. This type of test is simple and direct and measures a funda- mental skill. Tests of the reading of single, real words typically require that the individual read a set of words aloud. These words may vary on several dimensions, but usually these dimen- sions are not systematically assessed. For example, words may be regular—that is, they follow the letter-sound corre- spondence rules of English (e.g., fat, block)—or they may be exceptions to these rules—that is, they involve irregularity or unpredictable letter-sound correspondence (e.g., have, said, island, sword). A person may have difficulty with the irregu- lar but not the regular ones. The words may be more familiar and in the person’s vocabulary, such as cat, book, and red, or they may be less familiar, such as predatory, terpsichorean, and oligarchy. Obviously, what is familiar and what is unknown depends on the age, vocabulary, and experience of the individual. Some words may be read correctly because they have been encountered before, whereas others may be read incorrectly (but almost correctly; e.g., intrigue read
Assessment of Learning Disabilities 477 individual’s vocabulary and have not been encountered before. The confounding of familiarity with other dimensions of a word makes the construction of a word-reading list a difficult task. In the case of each particular word, one simply does not know when a person reads a word correctly whether he or she has merely memorized it. Note that pseudowords do not present this difficulty. The reading of both words and pseudowords assesses the basic problem in a reading disability—that is, difficulty with phonological processing; both tasks are relatively straightfor- ward. However, the measurement of text processing becomes more complex. Text processing is typically measurable by tests that involve the reading of sentences and paragraphs. In both cases, there are often clues about the word from the sur- rounding context. Typically, nouns follow articles, verbs fol- low subjects, adjectives precede nouns, and so on. When an individual reads a word in context correctly, we do not know whether he or she has read the word or made a good guess from the context. Note that this problem is not an issue with the reading of single words or pseudowords. The reading of sentences or paragraphs may occur silently or aloud. If the reading is silent, there is no way of assessing what the person is actually reading, although this type of reading may be more similar to what occurs in many reading situations. Questions about what has been read are the princi- pal means to assess comprehension. In most cases, memory is a very important aspect of the testing of sentence and para- graph comprehension. Often, the material is removed so that it is not available when the questions are asked. The person may have read quite well but may forget the answer to the question. Even when the material is available, the individ- ual’s performance is timed, or a fixed time is allowed to complete the test. At least some of the variance between indi- viduals may be caused by variations in reading rate or speed of task completion—not a differential understanding of the material. There is, however, a significant difference between a slow reader and one who may not even be able to decode the words in the first place. Some students are able to decode the words and answer the questions on a reading comprehen- sion test but need more time. Some have a problem with decoding the words. An assessment should be able to differ- entiate these two difficulties. Reading tests vary in the output or type of response that is required. Some require an oral output that may involve some degree of facility with expressive language, whereas others require a written output—for example, answering multiple- choice questions. Still others involve having the person select a synonym for a word; in reality, this test is a measure of vocabulary. An individual may select the incorrect word not because of poor reading skill, but because he or she is not sure of the correct synonym. The actual comprehension questions themselves may vary in several dimensions. They may involve inferences, mem- ory for details, or the general point of the passage. It is very likely that a large part of reading comprehension ability con- sists of memory skills (e.g., Tal & Siegel, 1996). The individ- ual must decode words and obtain meaning from them, but also he or she must retain the information in working mem- ory and be able to answer questions about the content of the reading passage. It seems apparent, however, that memory is still a significant factor in tasks in which recall of exact word- ing or details is not essential. In these cases, the meaning must be retained and then operated on in some manner to produce an expected answer. The individual’s familiarity with the material in the text can determine how the person will score on a reading com- prehension test (e.g., Drum, Calfee, & Cook, 1981; Marr & Gormley, 1982; Schneider et al., 1989). For example, Schneider et al. found that background knowledge about soc- cer influenced comprehension of and memory for a story dealing with soccer, but there were no significant differences between children with high and low verbal aptitude skills. Therefore, background knowledge was a critical factor in text comprehension, but verbal ability was not. Time to read can also be an integral part of the reading score. A number of factors can contribute to differences in the time taken to read a passage. For example, a person who recalled information about the story may have a faster time than does someone who could not recall the target informa- tion but who could remember its spatial location and look back quickly, who may in turn have a faster time than does a person who could not remember anything about the target information and had to search throughout the passage. Daneman (1984) has reported that much of the variance in reading comprehension scores disappears if individuals are allowed to look back at the passage that has just been read. Another difficulty with reading comprehension tests is that frequently the questions can be answered with a reason- able amount of accuracy without reading or comprehending the passage (e.g., Tal & Siegel, 1996). Such questions as
cows are not likely to be kept in cars, closets, or bathtubs. Obviously, the problem with having so much variability in the measurement of reading comprehension is that many different skills are assessed. Theoretically, there are many types of possible reading difficulties if this kind of measure of reading is used because the person could have a problem in any one or more of these components. Clearly, some of these combinations are more likely than others are, but the point is that it is unclear which dimensions are creating the problem when the individual achieves a low score on one of these sentence or paragraph reading tests. An individual may |
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