Learning disability testing methodology

Article © Nancy Cowardin, Ph.D.; used with permission.

Nancy Cowardin, Ph.D.
Educational Diagnostics

For additional information, please contact Nancy Cowardin at ediagnostics@earthlink.net.

Formal assessment for Learning Disabilities requires standardized educational tests in four functional areas: Intelligence, Academic Achievement, Language and Information Processing. Of course, all testing must adhere to administration guidelines published in accompanying clinician's manuals.

Intelligence

An IQ test must be administered to rule out mental retardation and to procure a score for IQ-achievement comparisons in academic subjects. This test must utilize 15 point standard deviations and yield a mean of 100 (the statistical population mean). Where cultural or language differences prohibit fair assessment of verbal intelligence, a nonverbal test may be used for score comparison purposes.

Academic achievement

Achievement testing requires a complete battery focused on three academic areas: reading, mathematics, and written language (spelling). Reading may further be broken down into the two subareas of decoding individual words and comprehending text. Similarly, math may be split into subskills of computation and practical application in daily circumstances. The spelling test that I use requires subjects to self-produce written language (as opposed to simply choosing the correct word from several provided) as words are dictated. All academic subtests yield standard scores which are used in the IQ - achievement comparison formula. Here a "significant" discrepancy is translated to mean that achievement falls 22 points (or more) below the IQ (expected) level.

Information processing

For most people, information is received, processed, recalled, and expressed using the two basic modalities of vision and hearing. Thus, both modalities require assessment to ascertain whether deficits in these basic processes are responsible for observed IQ-achievement discrepancies. Testing in this area may be taken from one battery (learning aptitude) or may utilize several independent tests knows to measure particular subskills within modalities. Either combination of tests should focus on auditory or visual attention, encoding of information, organization and processing, memory and retrieval, and expression. It is helpful if these tests yield mental age scores which can then characterize the magnitude of age-discrepancies in subprocesses and modalities.

Language

Language-based Learning Disabilities is a common occurrence, especially where reading and written language are deficit areas, thus most assessors look at receptive versus expressive language capabilities in test subjects. I prefer to use simple vocabulary measures to compare these language subareas as well as to exact yet another composite measure of mental age in clients. This can also guide further testing in social maturity or moral development, both language-based skills, if needed for a more complete developmental profile.

Procedure

Educational professionals are ethically bound to maximize the potential of tested students/clients wherever possible. This requires determination of the client's physical status, health, and willingness to participate in the assessment process. Also, differential testing standards may be applied where, in the assessors' judgment, standard procedures would tend to depress scores prejudicially. For example, rewording of test items in non-language areas (e.g., mathematics problems) is allowable to prevent language deficits from compounding scoring in these problem-solving processes.

It is my intention to elicit the best possible effort from clients in all test areas. On an ongoing basis, I observe the client's body language and note verbal indications of "struggle behavior" in difficult test areas. Generally, this behavior should be observed to increase as test content becomes more difficult. Additionally, I watch for failure to try, apathy or malingering, if present, and note these behaviors in my final report. If a client's effort varies widely across tests, I note so in the report as well. Finally, I control for malingering by presenting clients with four test batteries which contain some duplicate items over the several-hour process. This enables the clinician to check for error consistency and/or error correction during testing. For example, it is possible for a subject to recall an item receptively (when presented to him with several other items) which he did not know expressively (self-produced), but the reverse is not typical.

Finally, each assessor's test battery is personally chosen according to his or her experience and comfort with the procedures. Tests chosen by another professional may differ from my own, but both batteries should, at the very least, produce information useful in the IQ-achievement discrepancy formula plus supporting information processing data which describes observed academic deficits.

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