JCPSLP Vol 22 No 1 2020

Heard word /dog/

Phonological input buffer

Phonological input lexicon

Object/picture

Phoneme to grapheme conversion

Semantic system

Orthographic output lexicon

Graphemic output buffer

Written spelling dog

Oral spelling “dee – oh – gee”

Typing d-o-g

Figure 1. Schematic overview of the cognitive process of spelling (writing to dictation and written naming). The solid line represents the lexical pathway, the (inner) grey dashed line represents the direct non-semantic lexical pathway, and the (outer) black dashed line represents the sub-lexical pathway.

called “phonologically plausible” errors, where irregular words are spelled according to the most common phoneme-grapheme correspondences (e.g., said ➝ sed , yacht ➝ yot , enough ➝ enuf ). Words with a regular spelling, such as lip , or nonwords like mip (also known as pseudowords), can still be spelled correctly by relying on regular phoneme-grapheme rules (i.e., the phoneme /l/ is spelled L). This pattern is called surface dysgraphia . Individuals with lexical route spelling problems usually also find words that are more frequent in their experience (e.g., job) easier to spell than words of lower frequency (e.g., jib), and words that refer to concrete concepts (e.g., house, dog) easier than those that are abstract (e.g., fear, truth). It is important to remember that poor irregular word spelling can occur because of difficulties anywhere along the spelling route. For example, semantic impairments can lead to poor irregular word spelling and will also impact spoken language comprehension and production. In contrast, if the orthographic output lexicon alone is impaired, this will only lead to poor irregular word spelling

spellings) is preserved, but the impairment to phoneme- grapheme correspondences results in difficulties with spelling nonwords or unfamiliar words. This pattern is known as phonological dysgraphia . This impairment has a less severe functional impact, given that most writing tasks only require spelling of familiar words. However, such individuals will have trouble with, for example, writing a name that they are not yet familiar with (e.g., of a person, street or product). Lexical and sub-lexical spelling problems. If individuals have problems with both the lexical and sub-lexical spelling routes ( mixed dysgraphia ), they will have problems spelling both words and nonwords, and may produce responses that are similarly spelled to the target word (e.g., chalk ➝ chap ). Some individuals, particularly those with semantic impairments, and completely abolished sub-lexical spelling ability, may also make semantic errors (e.g., cat ➝ dog ): a pattern known as deep dysgraphia . The graphemic output buffer After the spelling of a word is generated using either lexical or sub-lexical processes, it has to be stored and held active while the subsequent physical process of writing (or typing, or naming letters in oral spelling) is planned and executed. This component of the spelling process is the graphemic

while spoken language can be unaffected. 5 Sub-lexical spelling problems

In individuals who have a selective deficit in the sub-lexical spelling route, and no problem in the lexical route, the spelling of familiar words (with regular and irregular

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JCPSLP Volume 22, Number 1 2020

Journal of Clinical Practice in Speech-Language Pathology