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We report on an English-speaking, aphasic individual (RB) with a spelling deficit more severely affecting orthographically irregular words for which phonologically plausible errors (PPEs) were produced. PPEs were observed for all word forms, with the exception of inflectional suffixes, despite the irregular sound-print mappings of many inflectional suffixes (e.g., walked → /wɔkt/). RB's pattern replicates that reported in Badecker, Rapp, and Caramazza (Badecker, W., Rapp, B.,Caramazza, A. (1996). Lexical Morphology and the Two Orthographic Routes. Cognitive Neuropsychology, 13, 161-176). We extended their investigation by examining RB's spelling of derived words and found a selective deficit for derived words compared to inflected words in writing. This selective deficit did not appear to reflect differences in morphological transparency or suffix frequencies that exist between inflection and derivation. This is the first evidence that distinct neural mechanisms support inflection and derivation in spelling.

Writing has long been considered to be dependent on speaking. However, modality-specific dissociations between written and spoken word production imply that word production is supported by distinct neural mechanisms in writing, which can be impaired or spared regardless of the intactness of spoken word production. Rapp et al. (2015). Modality and morphology: What we write may not be what we say. Psychological Science, 26, 892-902 documented a double dissociation where problems with regular inflections were selectively restricted to writing or speaking. We report on two English-speaking aphasic individuals who exhibit this same modality-specific dissociation of inflectional processing, replicating the original findings. We expand on Rapp et al.'s study by examining whether the dissociations observed with regular inflections extend to other morphological forms, such as derivation and irregular inflection. Results showed that the dissociation holds for derivation; however, both participants were impaired with irregular inflections in both output modalities. Implications of these findings for morphological processing and the independence of the orthographic system are discussed.

Within the domain of inflectional morpho-syntax, differential processing of regular and irregular forms has been found in healthy speakers and in aphasia. One view assumes that irregular forms are retrieved as full entities, while regular forms are compiled on-line. An alternative view holds that a single mechanism oversees regular and irregular forms. Arabic offers an opportunity to study this phenomenon, as Arabic nouns contain a consonantal root, delivering lexical meaning, and a vocalic pattern, delivering syntactic information, such as gender and number. The aim of this study is to investigate morpho-syntactic processing of regular (sound) and irregular (broken) Arabic plurals in patients with morpho-syntactic impairment. Three participants with acquired agrammatic aphasia produced plural forms in a picture-naming task. We measured overall response accuracy, then analysed lexical errors and morpho-syntactic errors, separately. Error analysis revealed different patterns of morpho-syntactic errors depending on the type of pluralization (sound vs broken). Omissions formed the vast majority of errors in sound plurals, while substitution was the only error mechanism that occurred in broken plurals. The dissociation was statistically significant for retrieval of morpho-syntactic information (vocalic pattern) but not for lexical meaning (consonantal root), suggesting that the participants' selective impairment was an effect of the morpho-syntax of plurals. These results suggest that irregular plurals forms are stored, while regular forms are derived. The current findings support the findings from other languages and provide a new analysis technique for data from languages with non-concatenative morpho-syntax.

We report on an English-speaking, aphasic individual (TB) who showed a striking dissociation in speaking with the different forms (allomorphs) that an inflection can take. Although very accurate in producing the consonantal inflections (-/s/, -/z/, -/d/, -/t/), TB consistently omitted syllabic inflections (-/əz/, -/əd/), therefore correctly saying "dogs" or "walked," but "bench" for benches or "skate" for skated. Results from control tests ruled out that TB's selective difficulties stemmed from problems in selecting the correct inflection for the syntactic context or problems related to phonological or articulatory mechanisms. TB's selective difficulties appeared instead to concern morpho-phonological mechanisms responsible for adapting morphological elements to word phonology. These mechanisms determine whether the plural inflection surfaces in the noun bench as voiced (-/z/), unvoiced (-/s/) or syllabic (-/əz/). Our results have implications for understanding how morphological elements are encoded in the lexicon and the nature of morpho-phonological mechanisms involved in speech production.

Individuals with semantic dementia (SD) show progressive worsening of lexical-conceptual single word knowledge alongside preservation of nonsemantic aspects of language. The current study examines morphological processing in SD. S.H.S., a Hebrew-speaking person with SD, completed eight tasks that tested inflection, linear derivation, and nonlinear derivation at three time points over six and a half years. S.H.S. correctly produced plural nouns and judged the grammaticality of noun-verb and noun-adjective inflectional agreement. A steeper decline was seen in the ability to judge irregularly versus regularly inflected forms. S.H.S. judged nationality suffixes accurately and produced diminutive and agentive suffixes successfully. He also relied on morphological decomposition when performing lexical decision. Judgement of sentences consisting of derived verbal participles was intact with regard to morphological considerations alone, but impaired when semantic considerations determined grammaticality. S.H.S.'s performance suggests that structural aspects of word knowledge might be functional in the face of a severe semantic impairment.