JCPSLP Vol 22 No 1 2020

Table 1. Overview of behavioural characteristics of dysgraphia subtypes and options for assessment

Example assessment

Graphemic buffer impairment

Lexical & sub-lexical route impairment (mixed dysgraphia / deep dysgraphia)

Sub-lexical route impairment (phonological dysgraphia)

Lexical route impairment (surface dysgraphia)

Irregular word spelling Regular word spelling

PALPA 53 Written naming (regular & irregular) and PALPA 44 Writing to dictation (Regularity & spelling) PALPA 45 Nonword spelling & length Copy words and nonwords of various lengths with the word in sight and after a delay

7

3

7

7

3

3

7

7

Nonword spelling

3

7

7

7

Cross case copying

3

3

3

3

Cross case delayed copying Effect of word frequency Effect of imageability/ concreteness Effect of length (number of letters) Error types on words

3

3

3

7

Yes

No

Yes

Possibly

PALPA 40 Spelling to dictation: imageability & frequency

Possibly

No

Possibly

Possibly

No

No

No

Yes

PALPA 39 Writing to dictation: letter length

Error analysis

Letter errors (yacht ➔ yacst ); fragment errors (yacht ➔ ya ); non- linear spelling

None

Visual errors (chalk ➔ chap ); semantic errors (yacht ➔ boat )

Regularisation/ phonologically plausible errors (on irregular words) (yacht ➔ yot )

Note. 3 = (relatively) intact; 7 = impaired. PALPA = Psycholinguistic Assessments of Language Processing in Aphasia (Kay, Lesser, & Coltheart, 1992). In this table lexical and sub-lexical route impairment refers to impairment to processes prior to the level of the graphemic buffer. Graphemic buffer impairment can co-occur with any of the other impairment types.

Error types and distribution Finally, it is important to investigate the type and distribution of errors, to be able to confirm the level of impairment. Impairment to the buffer usually leads to error types that reflect a problem with the activation and maintenance of letter information, and letters may be added, deleted or substituted. Also, any abnormalities in the process of writing such as the order of writing should be noted. It is important to remember that “pure” cases of graphemic buffer impairment are rare, and often it is accompanied by other types of spelling impairment, such as lexical and There are a number of reasons to choose to focus on or include writing in treatment. In a society where writing is an important means of communication, reduced writing skills can restrict an individual’s participation in social and professional life, and functional writing treatment can thus help reduce social isolation (Parr, 1995; Pettit & Tope, 2018; Thiel, Sage, & Conroy, 2015). Furthermore, when writing skills are better preserved than oral language in stroke aphasia, or when spoken language is deteriorating faster than written language in the context of progressive aphasia, writing can become an important means of communication sub-lexical impairment, complicating diagnosis. Approaches to graphemic buffer treatment

errors in both modalities. In contrast, if the only language impairment is a semantic impairment then while written naming should be impaired (particularly for irregularly spelled words), writing to dictation of words and nonwords need not be as the direct (non-semantic) route and sub-lexical route will still be available. Effects of stimulus length and delay Third, particularly important for identification of graphemic buffer impairment is assessment of spelling of words with different numbers of letters (that are matched for other characteristics). In graphemic buffer impairment, spelling accuracy will worsen with increasing word length. In addition, copying after different delays can be a valuable diagnostic task for graphemic buffer impairment – greater delay should lead to poorer performance. Copying with the word in sight should be compared with a condition where the word is first shown to the client and then removed to be written from memory (immediately or 5 seconds after it has been removed from sight). Importantly, the participant should be asked to copy in a different case to that presented (e.g., if a stimulus is presented in capital letters, the participant copies it in lower case, or vice versa) to ensure that it is letter identities that are being remembered and not just letters as visual shapes (using a more general visual memory system).

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JCPSLP Volume 22, Number 1 2020

Journal of Clinical Practice in Speech-Language Pathology