severe learning disabilities || identification criteria for learning disabilities: a survey of the...

Hammill Institute on Disabilities

Identification Criteria for Learning Disabilities: A Survey of the Research LiteratureAuthor(s): Kenneth Kavale and Chad NyeSource: Learning Disability Quarterly, Vol. 4, No. 4, Severe Learning Disabilities (Autumn,1981), pp. 383-388Published by: Sage Publications, Inc.Stable URL: http://www.jstor.org/stable/1510739 .

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IDENTIFICATION CRITERIA FOR LEARNING DISABILITIES: A SURVEY OF

THE RESEARCH LITERATURE

Kenneth Kavale and Chad Nye

Abstract. A survey of 307 research studies in learning disabilities (LD) was con- ducted to determine the nature and characteristics of the LD identification criteria used. Five categories of LD identification criteria were found; however, in one half of the studies LD subjects were selected on the basis of previous classification or diagnosis. Besides the identification criteria categories, research studies were also surveyed for the actual identification criteria included. Six criteria were identified with exclusion, discrepancy, process, and neurological components being the primary ones. It was concluded that the learning disabilities research literature presents a divergent picture of the nature and characteristics of learning disabilities and reflects a lack of consensus regarding standard identification criteria. Consequently, the LD research literature does not present narrowly fo- cussed subject samples suggesting continued difficulties with generalization and replication of results.

The LD research literature is marked by am- biguities and confusion about the criteria to be used for LD classification (Adelman, 1979; Keogh, Major, Omori, Gandara, & Reid, 1980; Torgesen & Dice, 1980). Lovitt and Jenkins (1979) demonstrated how the absence of uniform identification criteria leads to a lack of uniform reporting of variables circumscribing the LD populations studied. Consequently, it is difficult to generalize findings and replicate studies.

For lack of a single agreed upon set of identification criteria, previous research efforts have been directed at delineating the parameters of established LD definitions. Thus, Gillespie, Miller, and Fielder (1975) and Mercer, Forgnone, and Wolking (1976) surveyed State Departments of Education to determine trends and variations in their identification criteria, while Vaughn and Hodges (1973) surveyed special education personnel to ascertain the ac- ceptability of extant LD identification criteria.

Thus, although information concerning the status of established LD identification criteria is available, the nature of the identification criteria

used in the LD research literature remains un- known. The purpose of this study was to analyze the characteristics of the identification criteria for LD found in research studies.

METHOD The survey covered research reports collected

from major journals dealing with LD research. Journals titles and years surveyed are listed in Table 1.

Studies meeting the following criteria were included in the survey: (1) LD (or a close syno- nym) was included in the title, and (2) the study reported an experimental investigation. A total of 307 research reports were found to meet the

KENNETH KAVALE, Ph.D., is Assistant Pro- fessor of Education, School of Education, University of California, Riverside.

CHAD NYE, M.A., is a doctoral candidate in Special Education, School of Education, Univer- sity of California, Riverside.

Volume 4, Fall 1981 383



TABLE 1

Journals and Years Surveyed

Title Years

Journal of Learning Disabilities 1968-1980

Learning Disability Quarterly 1978-1980

Exceptional Children 1968-1980

Journal of Special Education 1968-1980

Journal of Educational Psychology 1968-1980

Journal of School Psychology 1968-1980

Child Development 1968-1980

Journal of Experimental Child Psychology 1968-1980

Psychology in the Schools 1968-1980

Education Research Quarterly 1976-1980

inclusion criteria and hence were included in the data base.

RESULTS Categories of LD Identification Criteria

Examination of the 307 studies indicated that the selected identification criteria could be classified into several broad categorizations. In the psychometric category, LD was identified on the basis of test data, either in the form of a specified discrepancy or some formula-based classification. Studies in the intact (or established criteria) category were most often based on federal or state guidelines. When a study com- bined a variety of identification variables into a new pattern, it was classified in a category called idiosyncratic. If no identification criteria were reported in a study, but subjects were selected from established LD programs, the study was categorized as previous classification or diagnosis. Finally, when the title of a study re- ferred to LD subjects without presenting identification criteria, the study was classified under the none category.

Results of the survey showed that one half of the subjects were selected on the basis of previous classification or diagnosis. Presumably, the classifications were based upon established

identification criteria; however, the investigator chose to report neither those criteria nor the extent to which the chosen subject met established criteria.

A total of 24% of the studies fell in the psychometric category which was marked by considerable variability in the number of psychometric factors considered ranging from a single test score to a complex equation involving several test scores to determine a discrepancy. In most instances, the psychometric identification criteria were not placed within a theoretical framework but presented simply as an empirical basis for identifying learning disabilities.

In about one in five studies, LD subjects were selected on the basis of intact or established criteria based upon federal or state guidelines for LD. Typically, the investigator indicated the basic definition used and proceeded to describe the parameters used in selecting LD subjects based upon the definition. The intact category revealed considerable variability in terms of

specificity ranging from rather generalized, generic criteria to more stringent and specific criteria for designating a child as LD.

A small percentage (6%) of studies used idiosyncratic identification criteria for LD. In its

384 Learning Disability Quarterly



amalgamation of components from a variety of sources, the idiosyncratic category represented the most specific approach to identifying LD subjects. Because of their specificity, the idiosyncratic identification criteria proved to be most useful for research purposes, i.e., generalization and replication.

Very few studies (1%) provided no discernible identification criteria. The title of such studies indicated that LD subjects were included in the sample; however, no description was included of the criteria circumscribing the LD sample.

Further analysis within the categories of identification criteria can be provided for the psychometric and intact components. The studies (N = 74) using psychometric identification criteria universally included achievement as a primary variable. Three major types of achievement measures were most often used, i.e., total score, reading, or math score. Over one half (54%) of these studies included total scores on a standardized achievement measure. When a specific achievement measure was listed, the Wide Range Achievement Test was the over- whelming choice (58%). The second most frequently used achievement measure was the Peabody Individual Achievement Test (13%) followed by the Metropolitan Achievement Test and the Stanford Achievement Test (10%). Among the other achievement measures mentioned were the California Achievement Test (5%), Iowa Test of Basic Skills (2%), and SRA Achievement Test (2%).

In 39% of the studies using psychometric identification criteria, scores from a reading achievement measure constituted the primary factor. The most frequently used reading achievement test was the Gates-MacGinitie Reading Test (45%) followed by the Gray Oral Reading Test (34%). Two other popular reading measures were diagnostic tests: Durrell Analysis (10%) and Spache Diagnostic Scales (10%). Math achievement was the primary factor in 7% of the studies surveyed with the Key Math Diagnostic Test being the most commonly used measure (60 %).

Analysis of the intact or established category (N = 59) revealed that the majority of the criteria were taken from state definitions (68%), while 32% were based upon federal definitions. The most popular federal definition consisted of some approximation of the NACHC (1968) def-

inition (74%), while approximately 26% were related to the definition found in PL 94-142.

Identification Criteria in LD Research Besides the general categories, a finer level of

analysis was achieved by surveying the actual identification criteria used in the research studies. The individual categories were analyzed into six major identification criteria.

Exclusion. A large majority (72%) of the studies included an exclusion component which eliminated specific groups from consideration as LD. The excluded groups fell into three categories: 1) Children with sensory handicaps were most often excluded, with visual impairments being most often mentioned (79%), closely followed by auditory impairments (77%). (2) Children with behavioral difficulties. Within this category, behavior disorders were most often mentioned (59%) closely followed by environ- mental disadvantage (56%). Just over one half (51%) of the studies excluded children who were judged mentally retarded. 3) Groups mentioned in less than one half of the studies surveyed, i.e., physically handicapped (43%) and children experiencing a communication handicap as their primary difficulty (25%).

Discrepancy. Only slightly less prominent (68%) than the exclusion component was the discrepancy criterion involving academic retardation. Such retardation was manifested in a stu- dent's inability to demonstrate subject matter knowledge at a level commensurate with intellectual ability. The magnitude of the discrepancy ranged from 1-5 years with an average of 1.76 years across 209 studies.

Process. In 56% of the research studies surveyed, subjects were identified on the basis of a process disturbance. Such processes represented hypothetical constructs presumed to underlie learning ability. Among the processes mentioned, perceptual problems were the most commonly listed process disturbance (48%). Of the remaining processes, attention was the most prominent (42%), closely followed by memory (38%) and psycholinguistic processes (34%) - almost always measured by the Illinois Test of Psycholinguistic Abilities. The remaining processes included language (21%) and cognitive style (17%) - almost always associated with scores on the Matching Familiar Figures Test. The above percentages indicate that while pro-

Volume 4, Fall 1981 385



cess disturbances represent a major identification criterion in LD research studies, they are more often than not specifically identified.

Neurological. Approximately one third (36%) of the studies surveyed specified neurological involvement as an identification criterion for inclusion in an LD sample. Such neurological involvement most often (87%) took the form of minimal brain dysfunction (Clements, 1966) as indicated by "soft" signs, while only 13% specified "hard" signs as a prerequisite for inclusion. Consequently, most investigators who included neurological involvement as an identification criterion offered only tentative evidence for brain injury, and were will- ing to admit that their identified LD group only possibly included subjects with neurological dysfunction.

Intelligence. Although average intelligence is considered prerequisite for LD designation, only one quarter (26%) of the research studies surveyed specified an intellectual level. In deter- mining IQ level, 83% (N = 63) of the studies specified a total IQ (based upon either a single measure or a measure composed of both verbal and performance tests), while 11 % (N =8) stipulated only a verbal IQ, and 7% (N=5) specified a performance IQ measure only. In studies in which a specific IQ test was indicated, the Wechsler Scales (WISC) were the over- whelming choice (70%) with the Stanford Binet a distant second (10%). Among the other intellectual measures included were the Peabody Picture Vocabulary Test (7%) and the Slosson and McCarthy Scales (3%).

Behavior. The criterion least often specified (19%) as an identification criterion was behavior. Usually this factor was concerned with a subject's behavioral status which needed to ex- ceed specified limits for inclusion in the LD group. Over one half (52%) of the studies used teacher ratings as the primary indication of behavioral status. Other types of behavioral ratings were based on measures of peer status (25%) and social interaction (7%).

DISCUSSION Results of the present survey indicate that the

LD research literature reflects a lack of consensus regarding standard identification criteria for designating an LD sample. Although major criteria traditionally found in LD definitions were

present, the research literature was marked by diversity regarding the nature and prevalence of criteria used for LD identification. This diversity results in heterogeneous LD samples and a generic designation for a wide assortment of children. The consequences of sample heterogeneity under the common LD rubric in- clude difficulties in generalization and replication of individual study findings.

The lack of standard identification criteria was most clearly reflected in the finding that in one half of the studies surveyed LD subjects were selected on the basis of previous classification or diagnosis. In a majority of cases, the antecedent criteria were not specified making it difficult to determine the extent to which the subjects matched standard LD criteria. Torgesen and Dice (1980) found that LD populations were selected on the basis of previous classification or diagnosis in 16% of the studies in their survey compared to 50% in the present study. This dif- ference may be attributable to the total number of studies surveyed: 105 in the Torgesen and Dice (1980) study vs. 307 in the present survey.

Established identification criteria (usually based on federal or state guidelines) were used with relatively low frequency (19%) suggesting that investigators found these difficult to operationalize for subject selection purposes due to their global nature.

Instead, in an effort to operationalize LD identification criteria, investigators attempted to develop psychometric criteria based upon empirical evidence. Although these efforts circum- vent the difficulties inherent in the use of previous classification and intact selection guidelines, the psychometric criteria revealed considerable variability with respect to the number of factors considered. In some instances, psychometric criteria were of limited utility because of the inclusion of a single or a limited number of factors. Thus, while psychometric criteria hold promise for research purposes they presently suffer from the same lack of standardization found in other types of LD identification criteria.

With respect to identification criteria actually used, the research literature included most of the criteria found in commonly accepted LD definitions. These were not, however, included uniformly. The most prominent identification criterion was an exclusionary clause. Generally,




standard definitions imply equal exclusion of groups, but the present analysis found that cer- tain groups were excluded more frequently than others. The pattern of exclusion was quite similar to the results reported by Mercer, Forgnone, and Wolking (1976) suggesting that exclusion remains an important factor in LD identification because it remains easier to define what LD is not, than what it is.

Academic deficits as indicated by a discrepancy also appeared to be a primary component in selecting LD research samples. This finding is in accord with the results reported by Torgesen and Dice (1980) who found that 64% of the studies surveyed included a discrepancy clause compared to the 68% in the present study. These results suggest an increasing emphasis on a discrepancy component as a primary identifying characteristic of LD compared to the earlier findings of Mercer, Forgnone, and Wolking (1976) indicating that only 29% of state definitions included a discrepancy clause. Additionally, the size of the discrepancy appears to have nar- rowed as indicated by the average 1.76 years found in the present study. Although the modal figure is placed at two years. LD research studies have apparently lowered this standard in subject selection.

The remaining criteria appeared to be receiving a decreased emphasis in terms of their consideration in identifying LD research samples. Neurological factors exhibited a decline when compared to the 70% inclusion figure obtained from state definitions of LD in the Mercer, Forgnone, and Wolking (1976) survey. The increased questioning of minimal brain dysfunction as a viable correlate of LD (Bateman, 1973: Koupernik, MacKeith, & Francis-Williams, 1975; Ross, 1976: Routh & Roberts, 1972) appears to be reflected in the reduced application of neurological factors in the subject selection for LD research.

Intelligence level also appeared to show decreased emphasis. Although 45% of the states in the Mercer, Forgnone, and Wolking (1976) survey listed an average IQ criterion, only 26% of the LD research studies surveyed here considered IQ as a selection factor. This diminished importance of intelligence level may reflect a broadening intellectual range for LD as sug- gested by studies which have failed to support the normal IQ criterion, and have reported that

anywhere from 25% to 40% of samples of LD children exhibited depressed intellectual func- tioning (Ames, 1968; Kirk & Elkins, 1975; Smith, Coleman, Dokeck, & Davis, 1977).

Finally, the process component, the assump- tion that LD results from deficits in psychological constructs underlying learning ability, also was given less emphasis compared to earlier findings. The survey by Mercer, Forgnone, and Wolking (1976) indicated that a process component was included in 83% of state LD definitions, while just over one half (56%) of the research studies analyzed here included a process component. This decrease in attention to processes may reflect the problems surrounding the relationship of processes to learning and the measurement of such processes (Mann, 1971, 1979; Salvia & Ysseldyke, 1981; Torgesen, 1979), as well as the recent recommendation by the National Joint Committee (see Hammill, Leigh, McNutt, & Larsen, in this issue) to eliminate the process deficit criterion from the definition of LD.

Within the process component, there appeared to be a shift in the stress placed upon individual processes. Although perception re- mained the most frequently mentioned process, attention was given increased emphasis. This increase parallels a growing interest in attention deficit as a primary difficulty of the LD child (Dykman, Ackerman, Clements, & Peters, 1971; Keogh & Margolis, 1976; Ross, 1976; Tarver & Hallahan, 1974). The present survey indicated that 42% of the LD research studies included an attention component compared to the 12% figure found by Mercer, Forgnone, and Wolking (1976). Although there are no com- parative data, the present findings appear to suggest that the processes of memory and cognitive style are also receiving increasing consideration as processes related to LD.

The LD research literature surveyed presented a divergent perspective of learning disabilities as illustrated by the identification criteria employed in LD research studies. This marked variability prevented any narrowing of the focus of LD identification criteria resulting in heterogeneous samples of children labeled LD. This suggests that LD currently represents a generic term as recognized in the National Joint Committee definition (see Hammill et al., in this issue). Although no consensus emerged with respect to LD identification criteria, the present analysis

Volume 4. Fall 1981 387



revealed that, while established components were prominent, new trends and emphases in LD identification criteria emerged. If these trends can be incorporated into the formulation of standardized LD identification criteria, it is likely that there will be increased consensus regarding the

parameters of LD and that, ultimately, the definitional problem may move closer to resolu- tion.

REFERENCES Adelman, H. Diagnostic classification of LD: Research

and ethical perspectives as related to practice. Learning Disability Quarterly, 1979, 2, 5-15.

Ames, L. A low intelligence quotient not often recognized as the chief cause of many learning difficulties? Journal of Learning Disabilities, 1968, 1, 45-58.

Bateman, B. Educational implications of minimal brain dysfunction. Annals of the New York Academy of Sciences, 1973, 205, 245-250.

Clements, S. Minimal brain dysfunction in children. NINDS Monograph No. 3, Public Health Service Bulletin No. 1415. Washington, DC: U.S. Depart- ment of Health, Education, and Welfare, 1966.

Dykman, R., Ackerman, P., Clements, S., & Peters, J. Specific learning disabilities: An attentional deficit syndrome. In H. Myklebust (Ed.), Progress in learning disabilities, Vol. 2. New York: Grune & Strat- ton, 1971, 56-93.

Gillespie, P., Miller, T., & Fielder, V. Legislative definitions of learning disabilities: Roadblocks to ef- fective service. Journal of Learning Disabilities, 1975, 8, 660-666.

Hammill, D.D., Leigh, J., McNutt, G., & Larsen, S. A new definition of learning disabilities. Learning Disability Quarterly, 1981, 4, elsewhere in this issue.

Keogh, B., & Margolis, J. Learn to labor and to wait: Attentional problems of children with learning disorders. Journal of Learning Disabilities, 1976, 9, 276-286.

Keogh, B., Major, S., Omori, H., Gandara, P., & Reid, H. Proposed markers in learning disabilities research. Journal of Abnormal Child Psychology, 1980, 8, 21-31.

Kirk, S., & Elkins, J. Characteristics of children en- rolled in the Child Service Demonstration Centers. Journal of Learning Disabilities, 1975, 8, 630-637.

Koupernik, C., MacKeith, R., & Francis-Williams, J. Neurological correlates of motor and perceptual development. In W. Cruickshank & D. Hallahan (Eds.), Perceptual and learning disabilities in children, Vol. 2: Research and theory. Syracuse, NY: Syracuse University Press, 1975.

Lovitt, T., & Jenkins, J. Learning disabilities research: Defining populations. Learning Disability Quarterly, 1979, 2, 46-50.

Mann, L. Psychometric phrenology and the new faculty psychology: The case against ability assessment and training. Journal of Special Education, 1971, 5, 3-14.

Mann, L. On the trail of process. New York: Grune & Stratton, 1979.

Mercer, C., Forgnone, C., & Wolking, W. Definitions of learning disabilities used in the United States. Journal of Learning Disabilities, 1976, 9, 376-386.

Ross, A. Psychological aspects of learning disabilities and reading disorders. New York: McGraw-Hill, 1976.

Routh, D., & Roberts, R. Minimal brain dysfunction in children: Failure to find evidence for a behavioral syndrome. Psychological Reports, 1972, 31, 307-314.

Salvia, J., & Ysseldyke, J. Assessment in remedial and special education (2nd ed.). Boston: Houghton Mifflin, 1981.

Smith, M., Coleman, J., Dokeck, P., & Davis, E. In- tellectual characteristics of school labeled learning disabled children. Exceptional Children, 1977, 43, 352-357.

Tarver, S., & Hallahan, D. Attention deficits in children with learning disabilities: A review. Journal of Learning Disabilities, 1974, 7, 560-569.

Torgesen, J. What shall we do with psychological processes? Journal of Learning Disabilities, 1979, 12, 514-521.

Torgesen, J., & Dice, C. Characteristics of research on learning disabilities. Journal of Learning Dis- abilities, 1980, 13, 531-535.

Vaughn, R., & Hodges, L. A statistical survey into a definition of learning disabilities: A search for acceptance. Journal of Learning Disabilities, 1973, 6, 658-664.

Requests for reprints should be addressed to: Ken Kavale, School of Education, University of California, Riverside, CA 92521.




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