a Cognitive Science Department, Krieger Hall , Johns Hopkins University , Baltimore , USA.
b Psychology Department , Harvard University , Cambridge , USA.
Cogn Neuropsychol. 2018 Dec;35(8):430-457. doi: 10.1080/02643294.2018.1546683. Epub 2018 Nov 19.
Post-graphemic writing processes transform abstract letter representations into representations of writing movements. We describe an individual with an acquired post-graphemic writing deficit. NGN is normal in spelling words aloud, but impaired in writing words to dictation, with most errors involving letter substitutions (e.g., RUMOR written as BUMOR). NGN's deficit affects graphic motor plans, which specify the writing strokes for producing letters. Analyses of writing speed, fluency, and stroke patterns suggest that NGN's errors result from incomplete motor-plan activation. NGN's error rate is high for the first letter in a word, and declines across subsequent positions. On the basis of this serial position effect and other results, we propose that post-graphemic writing mechanisms include a graphomotor buffer, a writing-specific working memory that holds activated graphic motor plans bound to specific serial positions. We suggest that NGN's graphomotor buffer is damaged such that early serial positions are affected most severely. Finally, we present results speaking to the roles and capabilities of the graphomotor buffer, and the structure of graphic motor plans.
形后书写过程将抽象的字母表征转换为书写运动的表征。我们描述了一个患有后天性形后书写缺陷的个体。NGN 在大声拼写单词时正常，但在听写单词时受损，大多数错误涉及字母替换（例如，将 RUMOR 写成 BUMOR）。NGN 的缺陷影响图形运动计划，该计划指定产生字母的书写笔画。对书写速度、流畅性和笔画模式的分析表明，NGN 的错误是由于不完全的运动计划激活所致。NGN 在单词的第一个字母上的错误率很高，并且在后续位置上逐渐降低。基于这种序列位置效应和其他结果，我们提出形后书写机制包括图形运动缓冲区，这是一种专门用于书写的工作记忆，它将激活的图形运动计划绑定到特定的序列位置。我们假设 NGN 的图形运动缓冲区受损，以至于早期的序列位置受到的影响最严重。最后，我们展示了与图形运动缓冲区的作用和能力以及图形运动计划的结构相关的结果。
