JCPSLP Vol 22 No 1 2020

Conclusion Graphemic buffer impairment is characterised by similar spelling performance regardless of input or output modality or word type, errors involving letter substitution, deletion, addition or transposition, more errors with increasing word length and worsening performance after a delay. Spelling assessment should therefore include cross modality testing using different word types, an analysis of spelling errors across tasks, and an assessment of words of different lengths and a (delayed) copying task. Treatment of buffer impairment has primarily focused on intact abilities to circumvent the working memory difficulties, or targeted the spelling of a specific set of words. Treated words generally do improve as a result of treatment, but improvement of the buffer itself remains more elusive. Further work investigating the possible transfer of treatment effects to other contexts including functional writing is warranted to try to better understand the mechanisms of treatment to maximise the outcomes of graphemic buffer treatment for everyday writing. In sum, while much of the literature on acquired spelling disorders has focused on problems of retrieval of orthographic forms, this paper has sought to raise awareness regarding another level of impairment in spelling – graphemic buffer impairment. We believe that this is common in those with acquired spelling problems and often overlooked by clinicians. We hope that this brief overview will increase awareness and therefore lead to appropriately targeted treatment for these individuals. Notes 1 Written word production can include a variety of input and output modalities, e.g., writing to dictation, written naming, copying, typing, or free writing. We use “spelling” as an overarching term throughout the paper and specify the particular input/output modality where required. 2 In this paper we mostly report studies with individuals with stroke-aphasia; however, see Graham (2014) for a review on dysgraphia in progressive aphasia. Furthermore, the same subtypes of dysgraphia, including graphemic buffer impairment, have been reported in the developmental dysgraphia literature (see McCloskey & Rapp (2017) for an overview). 3 Graphemes are the letters that correspond to an individual phoneme, e.g., the three phonemes in the word ROCK are represented by the graphemes R, O, and CK. 4 It should be noted that the label “regular” may not be straightforward as some of these words contain phonemes that can map onto multiple, common, graphemes. For example, the phoneme /ee/ could be spelled using EA, EE or E.E: meat , meet, Pete . This inconsistency of phoneme-grapheme correspondences can be complicated even further when certain spellings are more common depending on context (e.g., the phoneme /ai/ is most frequently spelled AY in the final position of a word [ lay ], but as A.E when followed by another phoneme [ late ]). Spelling performance has been shown to be influenced by these factors, and therefore it is possible that in surface dysgraphia not all “regular” words will be spelled accurately. 5 Impairments to auditory input processes (phonological input buffer, phonological input lexicon) will also impact spelling to dictation, but would not result in impairments to written naming. This reinforces the importance of

converging evidence in assessment to ensure accurate diagnosis of the source of the spelling problem within the language system. 6 Note that while spelling is expected to be impaired for all tasks, modalities and word types, and similar error types should be apparent, there may nevertheless be differences in the level of accuracy – different tasks/ modalities/word types have different demands that influence performance. For example, words are often more accurate than nonwords because they receive “support” from the stored lexical entry. Similarly, writing to dictation may be more accurate than written naming as the word form is provided rather than needing to be retrieved from the lexicon. 7 As regular words are able to be spelled using both lexical and sub-lexical routes they provide less clear diagnostic information than irregular words. References Barisic, K., Kohnen, S., & Nickels, L. (2017). Developmental graphemic buffer dysgraphia in English: A single case study. Cognitive Neuropsychology , 34 (3–4), 94–118. doi:10.1080/ 02643294.2017.1359154 Beeson, P. M. (1999). Treating acquired writing impairment: Strengthening graphemic representations. Aphasiology , 13 , 767–785. doi:10.1080/026870399401867. Beeson, P. M. (2004). Remediation of written language. Topics in Stroke Rehabilitation , 11 (1), 37–48. Beeson, P. M., & Rapcsak, S. Z. (2002). Clinical diagnosis and treatment of spelling disorders. In A. E. Hillis (Ed.), Handbook on adult language disorders: Integrating cognitive neuropsychology, neurology, and rehabilitation (pp. 101–120). Philadelphia, PA: Psychology Press. Bruce, C., Edmundson, A., & Coleman, M. (2003). Writing with voice: An investigation of the use of a voice recognition system as a writing aid for a man with aphasia. International Journal of Language & Communication Disorders , 38 , 131–148. doi:10.1080/136828202100004 8258 Caramazza, A., Miceli, G., Villa, G., & Romani, C. (1987). The role of the graphemic buffer in spelling: Evidence from a case of acquired dysgraphia. Cognition , 26 , 59–85. Cardell, E. A., & Chenery, H. J. (1999). A cognitive neuropsychological approach to the assessment and remediation of acquired dysgraphia. Language Testing , 16 , 353–388. De Partz, M. (1995). Deficit of the graphemic buffer: Effects of a written lexical segmentation strategy. Neuropsychological Rehabilitation , 5 (1–2), 129–147. Graham, N. L. (2014). Dysgraphia in primary progressive aphasia: Characterisation of impairments and therapy options. Aphasiology , 28 (8–9), 1092–1111. doi:10.1080/02 687038.2013.869308 Hillis, A. E., & Caramazza, A. (1987). Model-driven remediation of dysgraphia. Clinical Aphasiology , 17 , 84–105. Kay, J., Lesser, R., & Coltheart, M. (1992). Psycholinguistic Assessments of Language Processing in Aphasia (PALPA). Hove, UK: Lawrence Erlbaum Associates. Krajenbrink, T., Nickels, L., & Kohnen, S. (2015). Generalisation after treatment of acquired spelling impairments: A review. Neuropsychological Rehabilitation , 25, 503–554. doi:10.1080/ 09602011.2014.983135. Krajenbrink, T., Kohnen, S. & Nickels, L. (2017). No effect of orthographic neighbourhood in treatment with two cases

20

JCPSLP Volume 22, Number 1 2020

Journal of Clinical Practice in Speech-Language Pathology