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1.  Modality and morphology: What we write may not be what we say 
Psychological science  2015;26(6):892-902.
Written language is an evolutionarily recent human invention whose neural substrates cannot, therefore, be determined by the genetic code. How, then, does the brain incorporate skills of this type? One possibility is that written language is parasitic on evolutionarily older skills such as spoken language, while another is that dedicated substrates develop with expertise. If written language is parasitic on spoken language, then acquired deficits of spoken and written language should necessarily co-occur. Alternatively, if there are at least some dedicated written language substrates, these deficits may (doubly) dissociate. We report on five individuals with aphasia, documenting a double dissociation in which the production of affixes (e.g., jumping) is disrupted in writing but not speaking, or vice versa. The findings reveal considerable independence of the written and spoken language systems in terms of morpho-orthographic operations. Understanding these properties of the adult orthographic system has implications for the education and rehabilitation of written language.
doi:10.1177/0956797615573520
PMCID: PMC4418216  PMID: 25926478
2.  Frequency and regularity effects in reading are task dependent: Evidence from ERPs 
Language, cognition and neuroscience  2014;29(10):1342-1355.
Many theories of visual word processing assume obligatory semantic access and phonological recoding whenever a written word is encountered. However, the relative importance of different reading processes depends on task. The current study uses event related potentials (ERPs) to investigate whether – and, if so, when and how – effects of task modulate how visually-presented words are processed. Participants were presented written words in the context of two tasks, delayed reading aloud and proper name detection. Stimuli varied factorially on lexical frequency and on spellingto-sound regularity, while controlling for other lexical variables. Effects of both lexical frequency and regularity were modulated by task. Lexical frequency modulated N400 amplitude, but only in the reading aloud task, whereas spellingto-sound regularity interacted with frequency to modulate the LPC, again only in the reading aloud task. Taken together, these results demonstrate that task demands affect how meaning and sound are generated from written words.
doi:10.1080/23273798.2014.927067
PMCID: PMC4243684  PMID: 25436218
ERPs; Lexical Frequency; Spelling-to-sound regularity; visual word processing; task-dependent processing
3.  The analysis of perseverations in acquired dysgraphia reveals the internal structure of orthographic representations 
Cognitive neuropsychology  2014;31(3):237-265.
At a minimum, our long-term memory representations of word spellings consist of ordered strings of single letter identities. While letter identity and position must certainly be represented, it is by no means obvious that this is the only information that is included in orthographic representations, nor that representations necessarily have a one-dimensional “flat” structure. Evidence favors the alternative hypothesis that orthographic representations, much like phonological ones, are internally rich, complex multi-dimensional structures, though many questions remain regarding the precise nature of the internal complexity of orthographic representations. In this investigation, we test competing accounts of the internal structure of orthographic representations by analyzing the perseveration errors produced by an individual with acquired dysgraphia, LSS. The analysis of preservation errors provides a novel and powerful method for investigating the question of the independence of different representational components. The results provide clear support the hypothesis that letter quantity and syllabic role information are associated with, but separable from, letter identity information. Furthermore, the results indicate that digraphs, letter pairs associated with a single phoneme (e.g. the SH in FISH) are units of orthographic representation. These results contribute substantially to the further development of the multi-dimensional hypothesis, providing both new and converging evidence regarding the nature of the internal complexity of orthographic representations.
doi:10.1080/02643294.2014.880676
PMCID: PMC4016131  PMID: 24499188
Perseveration; spelling; orthographic representation
4.  Temporal stability and representational distinctiveness: Key functions of orthographic working memory 
Cognitive neuropsychology  2012;28(5):338-362.
A primary goal of working memory research has been to understand the mechanisms that permit working memory systems to effectively maintain the identity and order of the elements held in memory for sufficient time as to allow for their selection and transfer to subsequent processing stages. Based on the performance of two individuals with acquired dysgraphia affecting orthographic WM (the graphemic buffer) we present evidence of two distinct and dissociable functions of orthographic WM. One function is responsible for maintaining the temporal stability of letters held in orthographic WM, while the other is responsible for maintaining their representational distinctiveness. The failure to maintain temporal stability and representational distinctiveness give rise, respectively, to decay and interference effects that manifest themselves in distinctive error patterns, including distinct serial position effects. The findings we report have implications beyond our understanding of orthographic WM, as the need to maintain temporal stability and representational distinctiveness in WM is common across cognitive domains.
doi:10.1080/02643294.2011.648921
PMCID: PMC3427759  PMID: 22248210
working memory; spelling; dysgraphia; orthographic representations
5.  Underlying Cause(s) of Letter Perseveration Errors 
Neuropsychologia  2011;50(2):305-318.
Perseverations, the inappropriate intrusion of elements from a previous response into a current response, are commonly observed in individuals with acquired deficits. This study specifically investigates the contribution of failure-to activate and failure-to-inhibit deficit(s) in the generation of letter perseveration errors in acquired dysgraphia. We provide evidence from the performance 12 dysgraphic individuals indicating that a failure to activate graphemes for a target word gives rise to letter perseveration errors. In addition, we also provide evidence that, in some individuals, a failure-to-inhibit deficit may also contribute to the production of perseveration errors.
doi:10.1016/j.neuropsychologia.2011.12.001
PMCID: PMC3259193  PMID: 22178232
letter perseveration errors; dysgraphia; spelling; inhibition
6.  Representation of Letter Position in Spelling: Evidence from Acquired Dysgraphia 
Cognition  2010;115(3):466-490.
The graphemic representations that underlie spelling performance must encode not only the identities of the letters in a word, but also the positions of the letters. This study investigates how letter position information is represented. We present evidence from two dysgraphic individuals, CM and LSS, who perseverate letters when spelling: that is, letters from previous spelling responses intrude into subsequent responses. The perseverated letters appear more often than expected by chance in the same position in the previous and subsequent responses. We used these errors to address the question of how letter position is represented in spelling. In a series of analyses we determined how often the perseveration errors produced maintain position as defined by a number of alternative theories of letter position encoding proposed in the literature. The analyses provide strong evidence that the grapheme representations used in spelling encode letter position such that position is represented in a graded manner based on distance from both edges of the word.
doi:10.1016/j.cognition.2010.03.013
PMCID: PMC2953246  PMID: 20378104
letter position coding; dysgraphia; spelling; letter perseveration errors; orthographic processing

Results 1-6 (6)