Learning Disorders (dyslexia, dysorthographia, dyscalculia)

The term « Learning Disability » refers to a neurological condition capable of affecting various cognitive abilities linked to learning. This neurodevelopmental disorder interferes with the acquisition, the organisation, the retention, the understanding, the use and even the processing of verbal and non-verbal information. Dysfunctions such as learning disabilities occur despite adequate intellectual functioning or education, and cannot be explained by sensory deficits (vision, hearing), by another neurological condition, nor by unfavorable socio-economical or socio-cultural conditions.

We recognize the presence of a learning disability in individuals presenting with difficulties acquiring reading, writing, comprehension or mathematical skills. What we call dyslexia (reading), dysorthographia (writing and spelling) or dyscalculia (mathematics) are actually three different manifestations of learning disabilities, each finding their neurological root in different regions of the brain and persisting throughout time. This specific point is important as it allows to distinguish a persistent Learning Disorder from learning difficulties, which are temporary, transient and generally short-lived.

Letter inversions are often thought of as signs of dyslexia (b’s and d’s being the stereotypes usually brought up), but the overall clinical picture goes well beyond these details. In fact, a learning disorder will come to interfere with the conceptualisation of sounds from a given language, with their written representation, with the treatment and conversion of letter and sounds, or the recognition and visual discrimination of syllables and words as a whole, with the notion of numbers, quantities or proportions and even the concept of mathematical equations. Such dysfunctions can occur in isolation just as they may present in a more generalized manner.

Common signs of a learning disorder (dyslexia, dysorthographia, dyscalculia)

A Learning Disorder can present in many different forms, depending on which function is affected. A dyslexia will affect reading, a dysorthographia will complicate writing and a dyscalculia  will disrupt the acquisition of mathematics. Typical manifestations and presentations are :

  • Apparent delays in the acquisition of English/French or mathematics
  • Hesitant or slow reading speed
  • Syllabic reading
  • Letter sequencing mistakes during reading
  • Words often replaced by visually similar ones
  • Not enough time to complete assignments or exams
  • Writes words by sound
  • Letter omissions or additions
  • Letter and/or number inversions
  • Segmentation of words
  • Fusion of words with pronouns/determinants
  • Spelling difficulties when copying
  • Recurrent difficulties with grammar
  • Significantly weaker grades in English (French), compared to other classes
  • Still counts on fingers
  • Difficulty with the integration of multiplication/division tables
  • Troubles with borrowing and carry-overs
  • Recurrent difficulties with mathematics, geometry or problem-solving
  • Significantly weaker grades in mathematics, compared to other classes

A Learning Disorder is in fact a neurological condition present throughout childhood, whose initial varied manifestations mainly appear during elementary. As such, it cannot suddenly explain one’s difficulties during college, university or adulthood.

We recognize three types of dyslexia and dysorthographia in people presenting with a learning disorder. They involve difficulties with either letter-sound decoding skills, visual and global recognition of words, or with difficulties in both of these reading/writing strategies.

1) Phonological Dyslexia and Dysorthographia

A phonological Dyslexia or Dysorthographia affects decoding strategies linked to letter-sound conversions. This means that a person will present with difficulties when having to accurately convert sequences of letters or syllables into sounds; this involves difficulties associated with the grapheme-phoneme conversion, where the written word is not the one that is read or spoken by the person. The individual will therefore make mistakes in the sequence or positioning of letters, will come to reverse some or invert syllables, will happen to add or omit letters, etc. This is especially true with regards to rare and complex words, or even to novelty words. More often than not, these individuals will therefore prioritize the global recognition of words, by trying to remember or recognize their overall shape in written form, or by attempting to guess them with the help of the initial letters. For example, the word “respiratory” could be written or read as “resipirtatory”, or even guessed as being “respiration” due to letter-sound sequencing difficulties.

2) Surface Dyslexia and Dysorthographia

These types of difficulties will instead affect word-form recognition, in essence represents one’s ability to visually recognize a word or to remember its shape when writing it down. While each written word possesses its specific shape and silhouette, individuals presenting with surface dyslexia will have difficulty visually recognizing some words. While they might instead try to guess them or mistake them for other visually similar words, such individuals will especially present with hesitant, syllabic and slow reading speeds because they rely instead on grapheme-phoneme conversion to get through their readings. For example, words like knock or scene might not be recognized as such, and misread as “k-nock” or “skene”. People with dysorthographia will present similar difficulties remembering the actual shape of words, thus preferring to write them phonetically, by sound; for example, they will tend to write “doe” and “disine” instead of dough or design.

3) Mixed Dyslexia and Dysorthographia

Being the most severe variant of the lot, a mixed dyslexia or dysorthographia will affect both decoding strategies while reading or writing, as much so the grapheme-phoneme as the word-form recognition.


In some cases, identifying a Learning Disorder can be a daunting task, as it is often confused with a lack of effort or even inattention. The opposite is also true, in that some academic difficulties are often attributed to a Learning Disorder, when in fact they stem from an underlying Attention Deficit Disorder. As a matter of fact, comorbidity between a Learning Disorder such as dyslexia and an ADHD is frequent. In North America, it is estimated that 35% of people presenting an ADHD also present with a Learning Disorder such as dyslexia, dysorthographia or dyscalculia.

An assessment in neuropsychology therefore allows for a thorough analysis of an individual’s characteristics and functioning, so as to better sort out the difficulties inherent in learning disabilities from those arising from other conditions (ADHD, perception and visual exploration, dysphasia, intellectual disability, etc.). Furthermore, by identifying the specific areas of struggle with regards to reading, writing or mathematical skills (decoding, grapheme-phoneme conversion, visual recognition, phonological spelling, comprehension, calculation or problem solving, etc.), the neuropsychologist will manage to characterize and identify the nature of the Learning Disorder (phonological, surface, mixed?) so as to help devise an individualized education plan and enhance reeducation through speech and language therapy or remedial services.