Neuropsychological assessment has historically been the province of evaluating individuals with some kind of brain trauma. However, in recent decades, the value of understanding cognitive processing skills and executive functions and their links to instructional practices for students has been acknowledged. In fact, academic subjects are considered to be byproducts of groups of cognitive processes that are necessary to learn and perform successfully in each subject area such that there is an arbitrary dividing line between the subjects and the brain processes themselves. In essence, the cognitive processes are the subjects.
A comprehensive evaluation of these processes implicated in learning and learning disorders includes assessing seven broad abilities and many more narrow abilities that are part and parcel of each skill area. It is essential to understand the part the different narrow abilities play in each ability domain in order to avoid making incorrect assumptions about students’ strengths and weaknesses. For example, an important broad ability, crystallized intelligence, measured by the WISC-V and required in reading, solving math problems, and generating narrative writing, is comprised of tasks that involve both the retrieval from long term memory of already acquired word definitions and identifying commonalities between dissimilar objects or ideas (i.e. concept formation). While each is part of this broad ability, each is also a very different skill. Consequently, if students score well when retrieving word definitions, but perform much less well in forming abstract concepts, then the overall broad ability score must be interpreted in this context. That is, if the overall ability score is Average because the scores on each task are combined, this does not necessarily mean that the student has Average crystallized intelligence. It may mean that a student has good rote recall, but weak abstract reasoning. Combining the scores masks the deficit. Peeling back the onion by differentiating between concept formation, an abstract reasoning skill, and long term recall, gives teachers and parents a roadmap about how to address students’ weaknesses by tailoring the approach to each student’s learning profile of cognitive processing strengths and weaknesses.
It is of equal importance not to omit assessment of any one of the broad ability areas. For example, many students who have difficulty reading suffer from dysphonetic dyslexia, a disorder of phonemic awareness where they are unable to decode or make connections between letters and sounds. Yet, there are some students whose decoding is not the issue. They may experience orthographic or surface dyslexia where they are unable to visually recognize the shapes and contours of letters and sounds or retrieve them from long term memory. Remember, reading begins visually although encoding happens phonetically. Students with undiagnosed surface dyslexia may unknowingly be prescribed a reading approach to correct a decoding problem rather than the difficulty with orthographic processing, resulting in rising frustration.
A competent neuropsychological evaluation will ferret out the subtleties that lie in the various narrow abilities that comprise each broad ability area. Most importantly, once the pattern of strengths and weaknesses is known, interventions can be targeted at the areas of deficit and utilize the areas of strengths to compensate. For professional evaluators, teachers, and parents, it is essential to understand before you do. Peeling back the onion may mean conducting either additional or targeted assessments to the areas suspected of being at the root of a learning problem. This kind of assessment approach, called cross battery assessment, is also individualized as it follows the principle of one size does not fit all. Peeling back the onion involves testing in the suspected area until you understand where the obstacles exist. Stopping the assessment prematurely may result in missing important information or clouding the interpretation of testing results.