Frontiers in Psychology (May 2015)
Comparison of dysgraphia impairments across writing-by-hand and two keyboard modalities
Abstract
Computer use is essential for tasks such as e-mail, banking and social networking and is important for communication and independence in persons with aphasia. However, most evaluations of dysgraphia have investigated handwriting exclusively. Buchwald and Rapp (2009) evaluated dysgraphia in handwriting and described dissociated distinctions between orthographic long-term memory (O-LTM) and working memory (WM). Greater word-level errors (e.g., semantic) and frequency effects were indicative of O-LTM impairment. Greater nonword-level errors and length effects indicated a WM-level impairment where the graphemic buffer was less able to maintain orthographic representation for correct order and letter production. Cameron, Cubelli, and Della Sala (2002) posit a common orthographic buffer for handwriting and typing where the orthographic buffer supports a single allographic system with subsystems for handwriting and typing. Thus, a buffer-level impairment should in principle affect writing and typing similarly. However, one additional consideration in keyboard use is the potential impact of divided attention (between keyboard and screen) and visual search. Alternatively, the availability of letters may potentially aid in letter activation and/or selection. To examine these questions, this study compares writing-by-hand (WBH) and typing on QWERTY and ABC keyboards. Lexical or buffer level impairments should result in similar accuracy across modalities. However, participants with buffer level impairments may show increased or decreased keyboard performance depending on how keyboard use interacts with impairments. Potential differential effects across keyboards could also potentially be seen, since the QWERTY keyboard could recruit procedural memory in previously proficient users like those included in this study, though the ABC keyboard could provide a strategy for letter search. Methods. Seven English speaking participants with chronic aphasia due to stroke participated. A cognitive neuropsychologist ruled out visual scanning/spatial deficits and neglect. All had within average performance on the Ruff 2&7 accuracy, suggesting good visual search abilities. Participants reported premorbid type-by-touch abilities and >30 hours/week of computer use. The Western Aphasia Battery revealed aphasia quotients from 73.3 to 91 (3 anomic aphasia (Participants 400, 402, 500), 2 conduction aphasia (Participants 401, 404), and 2 Broca’s aphasia (participants 501, 502)). Stimuli were drawn from the Johns Hopkins Dyslexia and Dysgraphia Batteries (Goodglass & Caramazza, 1986). Three word sets were matched on number of words (49) and letters (268), frequency and length (4-8 letters). Participants were presented with pre-recorded words over headphones and were given 30 seconds to write each word in each modality. Order of modality was counterbalanced across participants. Each response was scored for letter (accuracy and position), word accuracy and error type. Error classifications were lexical (semantic, real word, morphological, phonologically plausible) or nonlexical (letter error (e.g., substitution) and nonword) (Buchwald & Rapp, 2009). No participants exhibited allographic errors. Chi-squares were conducted on letter, word and error results with the significance level set at .01 due to multiple comparisons. Results. No accuracy or error type differences were observed for 5 participants. Nonword errors predominated for these participants. P400 exhibited higher letter accuracy on both keyboards compared to WBH, with significantly more nonlexical errors on both keyboards compared to WBH. P402 showed a reversed accuracy trend with WBH > QWERTY > ABC. Error patterns for P402 were predominantly nonlexical across conditions. Discussion. A lack of accuracy or error differences for 5 participants indicates a neutral effect of keyboard use despite an error pattern suggestive of buffer-level impairment. However, P402’s stepwise WBH-QWERTY-ABC accuracy decline suggests an interaction between a buffer-level impairment and keyboard use. Higher accuracy on the QWERTY compared to ABC keyboard may indicate recruitment of procedural memory on the QWERTY keyboard. P402's below average performance on the Trails B may be suggestive of more impaired executive function difficulties as compared to the other participants who scored within the average range (except for P404). P400’s higher keyboard accuracy may suggest aided letter activation and/or selection not available in WBH despite producing more letter-level errors in both keyboards. These findings suggest that there is the potential for dissociation in performance across handwriting and keyboard modalities. Interestingly, no difference was observed between the keyboards, despite more familiarity with QWERTY keyboards in this group. Additional (planned) length and frequency analyses will aid in interpretation of data.
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