operational definitions and learning disabilities || definition for definitions of learning...

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Definition for Definitions of Learning DisabilitiesAuthor(s): Kenneth A. Kavale, Steven R. Forness and Thomas C. LorsbachSource: Learning Disability Quarterly, Vol. 14, No. 4, Operational Definitions and LearningDisabilities (Autumn, 1991), pp. 257-266Published by: Sage Publications, Inc.Stable URL: http://www.jstor.org/stable/1510662 .

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DEFINITION FOR DEFINITIONS OF LEARNING DISABILITIES

Kenneth A. Kavale, Steven R. Forness, and Thomas C. Lorsbach

Abstract. This article examines the problem of definition in learning disabilities. First, the focus is on the nature of definition. It is suggested that available definitions of LD are not real in the Aristotelian sense of providing an essence. Rather, they are best viewed as providing stipulative meaning by representing information agreed upon by particular groups. What is stipulated, however, cannot be considered either true or false but only useful for practical purposes.

Practice requires operational definitions, which are also fraught with conceptual difficulties. Such difficulties are illustrated in a discussion of discrepancy. It is also suggested that operational definition is too narrowly focused and should be ex- panded by considering operational interpretations, based on the best available knowledge. Finally, an example is provided of how operational interpretations may be combined into a more comprehensive operational definition for classifying learning disabilities.

When an idea is wanting, a word can always be found to take its place.

Goethe The issue of definition has been among the

most contentious in the field of learning disabilities (LD) (Bursuck & Epstein, 1987). Thus, little consensus emerges in response to the question: What is LD? As a result, almost any treatise on LD devotes considerable attention to "the problem of definition." Although the LD field has demonstrated unprecedented growth without an agreed-upon definition, it is unlikely to continue unabated unless there is a more logical and rational means of defining LD. The resolution of fundamental problems requires an understanding of the phenomenon in question. Definition is among the most basic routes to such understanding. Consequently, definition is important and, while it is easy to be sardonic about LD definition, it remains true that no field can be truly successful without the basic framework provided by definition.

Reviewing definitions of LD offered since 1962, Hammill (1990) compared and contrasted the el-

ements in each. His analyses focused on conceptual definitions, presumed to be statements that describe LD theoretically. These definitions, in turn, are used to develop operational definitions, which are necessary for practical purposes.

Keogh (1983) elaborated the different purposes definitions might serve, including (a) a focus for advocacy, (b) a category for providing service, and (c) a condition requiring scientific study. Keogh suggested that the exemplars of one type are not automatically exemplars of another.

KENNETH A. KAVALE, Ph.D., is Professor of Special Education, University of Iowa. STEVEN R. FORNESS, Ph.D., is Professor, Inpatient School Principal, Chief of Psycho- logical Services, and Director, UAF, University of California, Los Angeles. THOMAS C. LORSBACH, Ph.D., is Associate Professor of Special Education, University of Nebraska at Omaha.

Volume 14, Fall 1991 257



These analyses are useful, but fail to address many fundamental difficulties related to LD definition. One such difficulty surrounds conceptual definitions and, while these "are important because one must have a clear idea of what learning disabilities are" (Hammill, 1990, p. 74), they fall short of providing that clear idea. Another difficulty surrounds operational definitions, particularly the way they are conceptualized and im- plemented. These two difficulties will be the focus of this discussion.

DEFINITION OF DEFINITION As a formal activity, definition is often taken

for granted; but, in reality, it is part of the field of logic and possesses many intricacies (see Miller, 1980; Rantala, 1977). For example, there is a long tradition of talking not about the definition of words, but the definition of things. Such a definition represents an attempt at cap- turing essence in the Aristotelian sense (Aristo- tle, 1960). Thus, the focus is on res or things rather than on words or nomina. The search for the definition of LD, therefore, is an inquiry about the thing "LD," not about the word "LD."

Spinoza (1949) suggested that "the true definition of each thing involves nothing and experi- ences nothing but the nature of the thing defined" (p. 42). Real definition attempts to show a thing-thing relationship because essence is never achieved through the use of words. Although such endeavors are interesting, essence as a thing-thing relationship is rarely attained. It is a mistake, therefore, to assume that a definition is real in any significant sense (Robinson, 1954).

The LD field, however, has operated as if its definitions were real and have captured the essence of the LD phenomenon. This assumption leads to a misguided sense of closure because any statement suggesting that essence is what is stated in a definition leads to a tautology. Essence implies a metaphysical reality, as in "x is yz," but in actuality only refers to the proposition that "the word 'x' is defined to mean yz." The basic problem is the effect of inherent vagueness in the formulation, "What is x?" Any response is likely to be ambiguous because real definition ne- cessitates that x means only one thing as opposed to many possible things (Robinson, 1954).

An analysis of LD would suggest that it means many different things as opposed to one thing.

Consequently, it is difficult to capture any essence for LD, and a real definition for LD seems not possible. In place of real definition, Hammill (1990) suggested that existing definitions of LD are of the conceptual type. However, this desig- nation also is not easily applied.

According to Kant (1900), conceptual definition means "to present the complete, original concept of a thing within the limits of a thing" (p. 137). Kant's statement embodies the notion of concept, a term that denotes a circumscribed set of characteristics; but it too has a formal structure that is not easily gleaned (see Tuomela, 1973). Hempel (1952) discussed the elements of concept formation and demonstrated how concepts must be experimentally validated. Many LD concepts do not possess an experimentally testable reference and, therefore, are best termed dispositional; they have a disposition to manifest some property, which differs from the claim that they manifest that property (Outh- waite, 1983). When a concept is not theoretically confirmed, it can be judged on the criterion of significance (Bergmann, 1958). Many LD concepts fall short on this criterion, and it is difficult to view any LD concepts as sufficiently es- tablished to be included in a conceptual definition (Kavale & Forness, 1985b).

Being neither real nor conceptual, LD definitions take the form of nominal definitions, whose objective is to correlate words to a thing (word-thing vs. thing-thing), the focus being on words as symbols (Miller, 1980). Two forms of nominal definitions can be observed: lexical and stipulative.

Lexical definitions are the type found in dic- tionaries and represent the customary meaning of a word at a particular point in history. Be- cause lexical definitions must appeal to a wide audience, they tend to be general and not very insightful. Beyond a general sense of learning problems in school, therefore, a lexical definition of LD would not be helpful.

Stipulative definition involves the explicit, arbitrary, deliberate, and self-conscious adoption of a meaning relation between words (Robinson, 1954). Once agreed upon, a stipulative definition provides the meaning for a word. Although this appears to be a rational process, difficulties occur when we start examining how the stipulation is accomplished (Rantala, 1977). The following conversation from Lewis Carroll's

258 Learning Disability Quarterly



Through the Looking Glass illustrates the difficulty with stipulative definitions:

'When I use a word,' Humpty Dumpty said in a rather scornful tone, 'it means just what I choose it to mean - neither more, nor less.'

'The question is,' said Alice, 'whether you can make words mean so many different things.'

'The question is,' said Humpty Dumpty, 'which is to be master - that's all.' Thus, in the process of stipulation, words

mean whatever a particular individual chooses that they should mean. Consequently, your stipulation may not be the same as mine. The difficulty lies in the absence of a rational means for deciding which stipulation is best. Thus, stipulative definitions possess only a heuristic value that suggests nothing about their validity or invalidity in a formal sense (Robinson, 1954).

STIPULATIVE DEFINITIONS OF LEARNING DISABILITIES

Although likened to conceptual definitions, available LD definitions are most properly viewed as stipulative. Over time, various individuals, groups, and organizations have acted like Humpty Dumpty in insisting that LD was to mean what they chose it to mean. Based upon conventional wisdom about what LD should be, a consensus was achieved about how to stipulate LD. Although these definitions have permitted growth and development, the presence of an almost perpetual "definitional problem" points to an underlying contention about the various stipu- lations.

Stipulative definitions must, of course, stipulate something. A major difficulty in LD definitions relates to the elements stipulated. Kavale and Forness (1985a) analyzed LD definitions and found five common elements, including the assumptions that (a) LD fits a medical model (im- plying something is wrong with the child); (b) LD is associated with (or caused by) neurological dysfunction; (c) LD academic difficulties are related to psychological process disturbance; (d) LD is associated with academic failure; and (e) LD cannot be due primarily to other handicap- ping conditions. These assumptions were evalu- ated critically and each was found to be problematic. Hence they cannot be accepted unequivocally. The authors suggested that the assumptions emanate from the seminal work of

Strauss and Werner (see Strauss & Kephart, 1955; Strauss & Lehtinen, 1947) and constitute a paradigm (see Kuhn, 1970). Through a series of historical linkages formed through Strauss and Werner, colleagues who were pivotal in the formation and development of the LD field, this paradigm has become an entrenched influence. Thus, it is perpetuated even though the empirical evidence is not supportive; in fact, it can be viewed as representing "reified concepts masquerading as actualities" (Kavale & Forness, 1985a, p. 19).

Thus, the elements stipulated in LD definitions are generally not valid and their value as fundamental indicators of LD can be questioned. This dilemma points out the primary difficulty with stipulative definitions: They need not be true but only useful. So long as there is consensus about the information included and a heuristic value is perceived, the definition is accepted and used for practical purposes. The problem lies in the limited understanding of the phenomenon provided by a stipulative definition and the assumption that it is a real definition that has captured the essence of LD. The definitions stipulated are not real. Even though they may cluster around common elements (see Hammill, 1990), there is no guarantee that they are true, but only that a significant degree of agreement has been achieved with respect to what is stipulated. Consequently, even while being useful, stipulative definitions may be right or wrong. The stipulative definitions of LD appear to be more wrong than right and, therefore, should be approached with caution if used to further our understanding of LD.

The stipulative definitions of LD also suffer from a lack of comprehensiveness, which fails to capture the complexity of the LD phenomenon. Although consensus is forged in stipulative definitions, the price paid is a narrow focus that does not cover all aspects of LD. Kavale and Nye (1985-86) demonstrated that LD is a com- plex and multivariate phenomenon not easily defined by any single area of functioning. Across four domains (linguistic, achievement, neuropsy- chological, and social/behavior) that included 38 variables, these authors were unable to identify an area that served as a primary source of LD. Therefore, this construct appears to involve a number of component deficits.

Consequently, it would be more appropriate to stipulate a broad range of behaviors in defin-




ing LD. Restricting the areas (e.g., listening, speaking, reading, writing, reasoning, or mathematical abilities) does not capture the complexity and provides too narrow a focus. The stipulation of, for example, "a heterogeneous group of disorders" is not sufficient because the reference is to subject variability rather than a range of associated disorders.

Another limitation of stipulative definitions of LD involves a number of invalid or, at least, equivocal assumptions that may be tolerated for practical pursuits but become problematic for understanding the LD phenomenon. The assumption that stipulative definitions are real may lead to the development of a false sense of understanding because the assumptions that form the basis of that belief may not be true. By im- plying essence, real definitions involve a significant sense of understanding that is difficult, if not impossible, to achieve. Stipulative definitions, in contrast, can never achieve the understanding incorporated in real definitions and, consequently, should not be mistakenly used as a basis for understanding LD. The Problem of Operational Definitions

Although the "definition problem" in LD has been paramount, the field has managed to develop because of the assumption that definition per se is not of primary import. Rather, the criti- cal aspect is the manner by which LD is operationalized. From a tradition of logical positivism, Bridgman (1927) was among the first to declare that a theoretical concept is meaningful orily if there is a repeatable operation by which it is es- tablished - or, only if it is "operationally defined."

An operational definition is conceived as a rule to the extent that the term is applied to a particular case if the performance of specified operations yields a certain characteristic result (Skinner, 1953). For example, "harder than" might be operationally defined by the rule that mineral, x, is to be called harder than another mineral, y, if the operation of drawing a sharp point of x across the surface of y results in a scratch mark on the latter. Each concept is matched with a set of operations that defines its scientific status. To know these operations is to understand the concept as fully as science requires (Dodd, 1943). This operationism (see Benjamin, 1955) provides not just a criterion of meaningfulness, but a way of discovering the

meaning of a particular concept: One need only specify the operations that determine its applica- tion.

Operational definitions, however, face difficulties from the point of view of formal definitional criteria. An explicit definition specifies a synony- mous meaning relation in the following form:

= df "...." which may be read, "...." (some term) is definitionally equivalent (df) to ".... (some other term[s]) (see Rudner, 1966). For example, 'discrepancy' = df 'difference between expected achievement and actual achievement.' With the definiendum on the left side and the definiens on the right, the specification of being definitionally equivalent implies that these terms are mutually replaceable without altering the truth value of the statement. This truth value, even when terms are replaced by definitionally equivalent terms, is the salva veritate condition for giving a definition significance.

But the salva veritate condition casts doubt on whether "operational definitions" are definitions at all. The processes named in an operational definition do not define anything, but merely convey a particular meaning for the operations required to test for the presence of the thing to which the operations refer. But the meaning can be conveyed in any number of ways, depending upon which indicators are chosen. For example, a variety of aptitude measures may be used to "define" expected achievement (i.e., IQ) and an even greater number of standardized achievement tests may be used to "define" actual achievement. Further variability is possible based on the IQ used (e.g., full scale, verbal or performance) or the type of achievement score used (e.g., grade equivalent, standard score). None of these could be considered definitionally equivalent; consequently, operational definitions do not meet the requirements for achieving the status of definition (Margenau, 1961).

Because of the difficulties inherent in assuming identical operations for a particular concept, operational definitions are not precise (Berg- mann, 1961). Thus, there is little justification for assuming that my operations are the same as yours. An operational approach assumes that different operations define different concepts, and is necessary if two individuals are to understand a concept in the same way. But each performance of the operations is different in some respects from any other. Unless these differ-




ences are dismissed as irrelevant, it is difficult to replicate operations exactly.

As Bergmann (1958) pointed out, there are no a priori rules to distinguish relevant from irrelevant operations in an operational definition. Any meaning constancy depends on the constancy of operations that cannot always be assumed with any confidence. In reality, it is necessary to allow for the possibility that the same concept is measured on the basis of completely different operations. For example, the assumption that LD students possess memory problems comes from a number of research investigations that included a number of different memory measures all leading to the same conclusion. Op- erationally, it is necessary to say that a number of different "memories" are in question. Although reaching the same conclusion, the operational differences obscure the significance of the conclusion. The obvious answer is that they all measure the same thing, but this statement is pre- cisely what operationism must deny.

Operational definitions are further weakened because most of the important theoretical concepts relate to experience only indirectly (Deese, 1972). Their empirical meaning depends on their relation to other theoretical concepts, but it is only those that have a sufficiently direct appli- cation to experience that tend to provide the most specific operations. For example, the level of school frustration in a student with LD is not measured by the manipulation of physical objects in any way comparable to the manipulation involved in measuring the hardness of a mineral. Although an operation could be used to measure school frustration, the interpretation of its outcome depends on the measuring of an open set of terms (e.g., school, frustration).

The solution to this problem has been the ad- vancement of "symbolic operations" involved in tracing the connections among theoretical terms, or between these and more directly observa- tional ones. But criteria for the usefulness or even admissibility of such operations are virtually impossible to formulate. Thus, inclusion of "symbolic operations" so "waters down" the op- erationist approach that it loses all its rigor, and begins to deal with metaphysical elements that undermine its preserved scientific status.

In one sense, operationism is contingent on the validity of its theoretical foundation (Hempel, 1961). In the most advanced scientific theories,

the form of argument is abstract and developed in some logical form or mathematical notation. In such cases, operationism may be acceptable, but the poor state of LD theory (see Kavale & Forness, 1985b) does not justify operationism because of the possibility of developing spurious (and meaningless) operations that are insignifi- cant.

Assume that a new "Learning Disabilities Co- efficient" (LDC) is proposed; by definition it equals the number obtained by multiplying white blood count by weight in ounces and dividing the product by head circumference in centimeters. Although it would be possible to determine a student's LDC, the LDC concept is obviously neither meaningful nor significant because, although we do not possess well-formulated and validated theories in a scientific sense, we do know a good deal about LD and the LDC in no way "fits" with existing knowledge about LD. Most operational approaches to LD possess a certain a priori plausibility, but the lack of cohe- sive and unified theory in LD (see Kavale, 1987b) soon undermines this plausibility.

OPERATIONAL DEFINITIONS OF LEARNING DISABILITIES

The proposed stipulative definitions of LD provide only global insight into the LD phenomenon. Actual practice (i.e., identification and classification) requires that the stipulative definitions be operationalized. Besides the difficulties with operationism discussed above, problems surface with respect to what is operationalized. Of the five assumptions reviewed earlier (Kavale & Forness, 1985a), only academic failure has been operationalized and thus used in actual practice. Over time, academic failure as operationalized in the concept of discrepancy has become the predominant (and sometimes only) criterion for LD classification (Frankenberger & Harper, 1987).

However, although almost universally accepted, discrepancy in the form of an aptitude- achievement difference is not usually even stated in any stipulative definition. In Hammill's (1990) analysis of 11 definitions, underachievement as defined by an aptitude-achievement discrepancy was found only in three, while the remaining eight referred to underachievement in the form of intraindividual variation. Thus, operational definitions of LD bear little resemblance to the




information provided in stipulative definitions.

Operational approaches appear to develop inde- pendently and seem to be decided upon through standards other than the elements agreed upon to describe the LD phenomenon. Instead, these standards appear related to such elements as convenience and efficiency rather than theoretical validity. Consequently, in an attempt to be useful, operational definitions may not reflect the major elements on which consensus has been achieved.

The primary operational definition of LD as underachievement measured by discrepancy appears to meet the convenience and efficiency criteria as evidenced by the use of tables or simple (perhaps even simple-minded) formulae for its implementation (Mather & Healey, 1990). Thus, the emphasis on criteria that stress usability seems to deflect attention from the theoretical difficulties embodied in the concept of discrepancy (see Kavale, 1987a).

Discrepancy is assumed to refer to the difference between expected and actual achievement. However, specifying expected and actual achievement poses another set of problems. One solution consists of identifying each of the terms with something already measured. Expected achievement is related to a prediction about school performance, and a bit of investigation shows that IQ is the best single predictor of school performance. An IQ score can be obtained from an intelligence test; therefore, intelligence tests provide an IQ score. In this context, the ongoing debate about how or why intelligence tests measure intelligence seems of little importance; it is sufficient to know that intelligence tests can provide an IQ score.

Actual achievement appears even easier to determine since a number of standardized achievement tests are available; that is, actual achievement can be provided by a standardized achievement test score. Again, it seems to make little difference that the obtained score in grade equiv- alents is problematic (Berk, 1982), that Kelley's (1927) 'jingle and jangle' fallacy may be operat- ing (i.e., the assumption that tests with the same labels measure similar functions or that tests with different labels measure different functions), and that scores are dependent on the test used (Jenk- ins & Pany, 1978).

How then is discrepancy measured? According to the operational interpretation, it is simply the

difference between expected and actual achievement. If the difference meets a stipulated, albeit arbitrary, criterion level (usually two years below grade level), a severe discrepancy is said to be present and the student is eligible for LD classification (Algozzine, Ysseldyke, & Shinn, 1982). It makes little difference that such difference scores are notoriously unreliable (Schulte & Borich, 1984), are influenced by the measurement model used (i.e., grade-equivalent versus standard score) (Reynolds, 1985), and are static with respect to a time dimension that may intro- duce very different levels of experience (Thorn- dike, 1963).

Using operationism as the method for measurement poses a basic difficulty and is the reason why LD suffers from a "measurement problem." Measurement, to be more than simply "the assignment of numerals to objects or events according to rules" (Stevens, 1951, p. 22), requires a theoretical component whose purpose is to link empirical indicators with abstract concepts (Zeller & Carmines, 1980). The purpose of theory is to link concepts and indicators ratio- nally and logically as well as empirically (Blalock, 1982). Without this theoretical base, measurement in LD has a limited scope and tenuous re- lationships, which produce a "measurement problem" (Kavale & Mundschenk, 1990). But the measurement problem is the result of operationism, which leads to a tautology that serves only to exacerbate the "measurement problem." For example, the question of construct validity is meaningless since an operational viewpoint suggests an affirmative response to the question, "Does this attention assessment measure what it purports to measure?" because attention can be no more than its operations for measurement. Thus, the instrument is said to measure attention because "attention is what it measures."

Operational measurement produces tautolo- gies that substitute for scientific rigor and do not verify a theoretical proposition. Thus, any measurement is by fiat, and attempts to validate it are of little value. For example, a discrepancy (difference) score may be validated by correlating it with school grades (in all probability a significant correlation would be found); that is, students with the greatest discrepancies also show the lowest grades. But, as Kavale and Forness (1985b) pointed out,

This is not theoretical verification but rather a




low grade of psychometric engineering. Vali- dation of this type substitutes the appearance of rigor for explicit theoretical derivation. By masquerading under the guise of operationalism, discrepancy so defined can only be re- garded as a delusion. There is no theory in the sense of an explicit and non-self-contradictory system, but only the appearance of one. (pp. 102-103)

CONCLUSION The "definitional problem" in LD is fraught

with many complexities making it difficult to achieve closure. One basic difficulty stems from a misunderstanding about the nature of definition. Present definitions of LD should not be construed as real in the sense that they specify an essence for LD. By considering the definitions to be real, it is easy to become seduced into thinking that a complete understanding of LD has been achieved. In reality, LD definitions are stipulative meaning that they represent simply a statement that has been issued by a particular group. Thus, a larger community interested in the same phenomenon may not find all elements stipulated in the definition to be acceptable. Indeed, the continuing LD "definitional problem" attests to the limited acceptability of any stipulated elements. At best, stipulation definitions are accepted, not because they enhance understanding, but because they permit "busi- ness as usual" in the service of program development.

What then is the status of LD definitions? First, as presently construed, they are neither "good" nor "bad," only useful. In promulgating the LD field, existing definitions have to be viewed as successful (perhaps too successful) and thus considered to meet the usability criterion. Second, they tell us relatively little about LD in any scientific sense. Instead, definitions of LD are convenient descriptive renderings of what LD is generally perceived to be. However, without any linkage to theoretical understanding, they do not actually describe the LD phenomenon. Third, additions or deletions to definitions like, for example, the addition of social skills to the list of LD deficits proposed by the Interagency Com- mittee on Learning Disabilities (ICLD, 1987), make little difference. If LD definitions are un- derstood as stipulative, contentious debate about the appropriateness of any addition or deletion

is futile because it simply represents one stipulation as opposed to another. To be useful, debate should center on the theoretical merits of the proposed addition or deletion (Forness & Ka- vale, 1991). Fourth, it is easy to understand why the problem of LD definition seems intermin- able. Stipulative definitions never really achieve closure and, as long as I can obtain the consensus of a particular group, my stipulation is as good as any other. Unless debate centers on theoretically derived statements (i.e., they can be proven valid or invalid), it is likely to continue because the lack of absolute criteria makes all ar- guments relative. And finally, unless the LD field is radically restructured, the "definitional problem" is unlikely to be resolved satisfactorily. Be- cause that scenario seems unlikely, present definitions should be accepted for what they are- stipulative definitions that do not provide a scientific understanding, but a global rendering appropriate for program development.

Thus, stipulative definitions are limited in scope and possess only a generic usefulness. As a result, they are not particularly useful and require transformation in order to be applied in practice. The most common transformation is found in operational definitions, wherein a concept is given meaning through its operations. Although appearing to be precise, operational definitions may measure the same concept in different ways, thereby introducing variability that is counter to operationism. Unlike the physical sciences, where the operations are fairly direct, the LD field must operationally define concepts that relate to experience only indirectly. Therefore, the theoretical connections are far more tenuous and any operational definition may possess limited meaning and significance.

The multitude of problems inherent in operational definitions suggests that they also need to be approached with caution. Although they seem more rigorous than stipulative definitions, their rigor may be more chimerical than real and may only represent stipulative definitions in a different form. Nevertheless, the concept of operational definitions may still be appropriate and may represent the best means of formalizing the LD field. For this to occur, however, a shift needs to take place in the manner operational definitions are viewed and used.

A first step might be found in a less restricted view of an operational approach. By nature, op-




erational definitions provide a narrow focus because they represent an attempt to find a corre- spondence with a single concept. Although appropriate, they only address a single concept and any one indicator probably fails to capture the complexity of the LD phenomenon. The difficulty seems to surround the notion of "definition," which implies a single statement but, when coupled with "operational," tends to produce a narrowly focused statement, too circumscribed for a multivariate phenomenon like LD. The solution seems to lie in moving beyond the notion of "operational definition" as a single statement and including a number of elements that may be defined operationally. To aid this process, Ennis (1964) suggested using "operational interpretations," which permits any number of concepts to be provided meaning by fo- cusing on concrete operations.

The process of "operational interpretations," however, needs a rational basis. If indeed the primary "operational definition" of LD is found in discrepancy, it must become only one among a number of possible interpretations, and others need to be chosen on the basis of logic and reason. The selection process should be founded on what is known about LD. In what areas is there sufficient theoretical understanding to include that element in a comprehensive description of LD? Once this question is answered, the focus shifts to the most appropriate "operational interpretation" of the concepts chosen. Ultimately, the areas should be ordered and sequenced into a hierarchical arrangement that might look like the one presented in Figure 1. (This is merely an example, and no assumptions are made about either its appropriateness or its validity.)

As illustrated in Figure 1, the outcome is a

Operational Interpretations

Level

I

III

IIIV

V

V

Discrepancy Aptitude-Achievement

Language Reading Math

Learning Efficiency

Strategy Rate

Attention Memory Perception Cognitive Processing

Social Cognition

Linguistic Processing

Problem Solving

Concept Formation

Metacognition

Necessary

Sufficient

Figure 1. An operational definition of learning disabilities.




structured arrangement that in its totality represents an operational definition, but is comprised of a number of operational interpretations. For example, the first step consists of documenting a discrepancy, followed by noting an achievement deficit in a specific academic area. The next level would investigate learning efficiency, followed by specific skill deficits at two levels. Each component is given an operational interpretation and moves in the direction of being necessary to sufficient conditions for LD classification. The outcome is a more complete "operational definition" of LD that includes validated components representing the best available knowledge about LD.

The "definitional problem" presents major difficulty for the LD field. It is unlikely that any combination or permutation of words defining LD will ever be universally accepted as "the" definition of LD. Instead, efforts should be directed at determining what a definition means in practice. This focus would lead to the realm of operational definition. What is required is a different perspective on the nature of operational definitions wherein it is viewed as a structure com- posed of a series of operational interpretations. As a more concrete approach to definition, operational definitions at least offer the possibility that debate about LD definitions moves away from endless semantic wrangling. If nothing else, discussion of this nature would provide a breath of fresh air to a stale debate.

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Requests for reprints should be addressed to: Ken Kavale, College of Education, Division of Curriculum & Instruction, N 238 Lindquist Center, University of Iowa, Iowa City, IA 52242.

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