Dyslexia is a specific learning disability that is neurological in origin, characterized by difficulties with accurate and fluent word recognition, poor spelling, and decoding abilities. These challenges are unexpected given the individual’s age and overall cognitive abilities. When a person struggles significantly with reading and spelling, a comprehensive evaluation is necessary to determine if dyslexia is the underlying cause. The process involves a structured battery of assessments designed to clarify the individual’s learning profile and provide a clear pathway for effective support.
Establishing the Scope of the Assessment
The dyslexia assessment is not a single test but a comprehensive evaluation performed by a qualified professional, such as a licensed psychologist, educational diagnostician, or a multidisciplinary team. Before in-depth testing begins, a review of the individual’s history is completed, and basic screenings are conducted to rule out other possible explanations for academic difficulties, such as vision or hearing problems.
The full assessment focuses on two primary areas: cognitive ability and academic achievement. Cognitive testing establishes the individual’s intellectual potential, often referred to as “IQ,” to confirm that the reading difficulties are “unexpected.”
Academic achievement measures document the individual’s current skill level across various subjects, with a particular focus on reading, writing, and spelling. By comparing the scores from these two areas, the evaluator determines if a significant pattern of strengths and weaknesses exists. This pattern must show a weakness in reading-related academic skills despite average or above-average cognitive potential.
Specific Tasks and Subtests Administered
The core of the evaluation involves a detailed battery of subtests that analyze the specific processing skills underlying reading and writing.
Phonological Processing
A major focus is on Phonological Processing, which is the ability to recognize and manipulate the sound structure of spoken language. Tasks in this area include having the individual break a word into its individual sounds (segmenting), blend sounds together to form a word, or identify words that rhyme.
Reading Fluency and Decoding
The individual is asked to read lists of real, common words to test sight recognition and lists of made-up, non-words (pseudowords) to assess the application of phonetic decoding rules. These tasks are often timed to measure the speed and automaticity of word recognition, which is a key marker of dyslexia.
Orthographic Processing and Spelling
Orthographic Processing is tested by examining the ability to recognize and recall letter patterns and the visual memory for words. The individual may be asked to spell words from dictation, including those that follow standard rules and those with irregular spellings.
Writing and Expressive Language
The examiner assesses writing and expressive language by having the person write sentences or a short essay to evaluate grammar, organization, and the application of spelling knowledge.
Processing Speed and Working Memory
The assessment includes measures of related cognitive functions, such as Processing Speed and Working Memory. A common task is Rapid Automatized Naming (RAN), where the individual must quickly name a series of familiar items, such as colors, objects, or letters, presented repeatedly on a page. These subtests help complete the cognitive profile by measuring how quickly visual or auditory information is processed and recalled.
Diagnostic Criteria and Post-Evaluation Planning
The diagnosis of dyslexia is established by carefully interpreting the standardized scores derived from the battery of assessments. A diagnosis is typically considered when scores in reading accuracy, fluency, and phonological processing fall significantly below expected levels, often in the 16th percentile or lower, despite scores in cognitive ability that are within the average range.
The diagnosis confirms that the individual has a Specific Learning Disability (SLD) with impairment in reading, specified as difficulty with word reading accuracy, reading rate or fluency, and spelling. Following the evaluation, the professional drafts a comprehensive written report that summarizes all findings, provides the formal diagnosis, and details specific recommendations for support. This document translates the complex test scores into an understandable narrative, outlining the individual’s unique learning profile.
The final step is outlining the post-evaluation plan. For students in a school setting, this often leads to the development of an Individualized Education Program (IEP). The report’s recommendations directly inform the goals and services included in the IEP, which might include academic accommodations like extended time on tests. Interventions typically involve structured literacy programs, such as those based on the Orton-Gillingham approach, which provide explicit, systematic, and multisensory instruction in foundational reading skills like phonemic awareness and decoding.