SLD and Intelligence
For some time, there has been the suggestion that IQ is not necessary in defining SLD (Siegel, 1989; Stanovich, 1991). This objection seems unwarranted because if the discrepancy criterion is replaced, then IQ testing would be eliminated given its function of documenting an expected achievement level. Additionally, in light of findings revealing that one empirically validated reading instruction method (i.e., systematic phonics) is not effective for cognitively limited, low ability children, IQ tests assume importance and assessing intellectual ability remains critical (Ehri, Nunes, Stahl & Willows, 2001). Special education has unfortunately come to de-emphasize the value of intellectual assessments (Morison, White, & Fever, 1996). Yet, the concept of intelligence and its measurement has been one of the most intensively studied topics, and it would be necessary to ask why so much attention has been paid to such a seemingly useless construct.
Some of the persisting negative perception of intellectual assessment stems from the fact that in the past IQ tests were developed under the strong influence of the concept of "g," the assumption that there is one primary cognitive ability (Buckhalt, 2002). For this reason, attempts to find diagnostic profiles based on scatter, recategorizations, patterns, or factor scores based on the Wechsler scales were not successful (Kavale & Forness, 1984). Over time, however, cognitive ability tests have moved away from "g" and there is now an array of well-normed, well-validated, theory-based tests of cognitive processes that measure multiple and complex processes or abilities (Kaufman & Kaufman, 2001). The value of IQ tests, therefore, lies in their ability to identify individual differences in cognitive functioning and the possibility of providing insight for understanding the nature of underlying process deficits (Kaplan, Fein, Kramer, Delis, & Morris, 1999). In turn, the enhanced understanding of cognitive processes will result in better individualized interventions (Naglieri, 2003).
Practically, IQ tests have only modest influence on the special education process. Specifically, it is certainly not the case that IQ testing is an impediment to obtaining special education services (Fletcher, et al., 1998). The 150% increase in students classified as SLD attests to the absurdity of this charge. The testing of IQ is vilified because the term "intelligence" may create positive or negative impressions about a student. For example, special education eligibility based on SLD determination is viewed as positive and an entitlement while eligibility based on MR or ED is viewed negatively and potentially punitive. Clearly, there are significant negative perceptions for some classifications and these perceptions are what make IQ tests appear villainous since they provide the basis for receiving a positive or negative label (MacMillan, Gresham, Bocian, & Lambros, 1998).
The use of IQ tests in documenting discrepancy does not restrict access to special education; again, the sheer number of students served under the SLD classification attests to this fact. If the discrepancy model was implemented more rigorously, the SLD classification rate would probably become fairly constant. But the discrepancy model is not implemented rigorously and systematically as suggested by Gottlieb, Alter, Gottlieb, and Wisher (1994) who stated that "the discrepancy that should be studied most intensively is between the definition of learning disability mandated by regulation and the definition employed on a day-to-day basis in urban schools" (p. 455). Similarly, MacMillan et al. (1998) remarked that, "We did not anticipate the extent to which the process would yield children certified as LD who failed to meet the discrepancy required by the education code" (p. 322). The lack of rigor, however, has created a relative discrepancy model where SLD determination depends on the level of performance compared to other students in that school (Peterson & Shinn, 2002). Additionally, a strict ability-achievement discrepancy model has also been replaced by an absolute low achievement model where, for example, most students with borderline IQ receive special education as SLD. These modifications occur because the individual school setting (i.e., context) influences the way the presence or absence of a disability may be identified. For example, if the average reading ability in a particular classroom is 90, a student with an IQ of 110 and reading score of 85 would not appear out of the ordinary in terms of reading achievement and may not be identified, but a student with an 80 IQ and 75 reading score may appear to have a disability in that context. When a student is first referred, the influence of context should be evaluated to determine whether or not there is a real possibility that a disability does, in fact, exist. The lack of attention to context and the implementation of alternative discrepancy models means that IQ-achievement differences are often not provided the opportunity to identify underachievers a necessary component of SLD identification (MacMillan & Siperstein, 2002). Besides context, perceptions about disability also play a significant role (Lovitt & Cushing, 1999). The positive connotation associated with SLD makes it the disability category of choice and provides an easy way for schools to placate parents who are less willing to accept an MR or ED classification. In part, the problem with the ED classification is the negative connotation surrounding the term and what may happen in a school setting (McEvoy & Welker, 2000). More importantly, however, is the failure of the ED identification process to consider associated cognitive impairments, particularly those related to executive functioning and social cognition that often result in inadequate service delivery and the promotion of an attribution bias where student behavior is viewed as being caused by either willful defiance (choose to be "bad") or a lack of emotional control (Hinshaw, 1992). Such negative causal attributions often lead to punitive rather than accommodative or remedial interventions.