Time reference in Indo-European languages is marked on the verb. With tensed verb forms, the speaker can refer to the past (wrote, has written), present (writes, is writing) or future (will write). Reference to the past through verb morphology has been shown to be particularly vulnerable in agrammatic aphasia and both agrammatic and…

This paper investigates the cognitive processes underlying picture naming and auditory word repetition. In the two-step model of lexical access, both the semantic and phonological steps are involved in naming, but the former has no role in repetition. Assuming recognition of the to-be-repeated word, repetition could consist of retrieving the…

This study presents the first direct comparison of immediate serial recall in semantic dementia (SD) and transcortical sensory aphasia (TSA). Previous studies of the effect of semantic impairment on verbal short-term memory (STM) have led to important theoretical advances. However, different conclusions have been drawn from these two groups. This…

Across most languages, verbs produced by agrammatic aphasic individuals are frequently marked by syntactically and semantically inappropriate inflectional affixes, such as "Last night, I walking home." As per language production models, verb inflection errors in English agrammatism could arise from three potential sources: encoding the verbs'…

Lexical access in language production, and particularly pathologies of lexical access, are often investigated by examining errors in picture naming and word repetition. In this article, we test a computational approach to lexical access, the two-step interactive model, by examining whether the model can quantitatively predict the repetition-error…

Many facts about aphasic and nonaphasic naming are explained by models that use spreading activation to map from the semantics of a word to its phonology. The implemented model of picture naming discussed here achieves this by coupling interactive feedback with two selection steps. The model's structure and default parameters were set up to match…

Nonaphasic speakers are known to take longer to name pictures when they are blocked by semantic category and repeated multiple times. We replicated this ''semantic blocking effect'' in older controls and showed that in aphasia, the effect is manifested in increased error rates when naming semantically homogeneous, compared to mixed blocks. We…

Many recent models of language comprehension have stressed the role of distributional frequencies in determining the relative accessibility or ease of processing associated with a particular lexical item or sentence structure. However, there exist relatively few comprehensive analyses of structural frequencies, and little consideration has been…