An interactive 2-step theory of lexical retrieval was applied to the picture-naming error patterns of aphasic and nonaphasic speakers. The theory uses spreading activation in a lexical network to accomplish the mapping between the conceptual representation of an object and the phonological form of the word naming the object. A model developed from the theory was parameterized to fit normal error patterns. It was then "lesioned " by globally altering its connection weight, decay rates, or both to provide fits to the error patterns of 21 fluent aphasic patients. These fits were then used to derive predictions about the influence of syntactic categories on patient errors, the effect of phonology on semantic errors, error patterns after recovery, and patient performance on a single-word repetition task. The predictions were confirmed. It is argued that simple quantitative alterations to a normal processing model can explain much of the variety among patient patterns in naming. Difficulty in word retrieval is the most pervasive symptom of language breakdown in aphasia. As with other symptoms of brain damage, word retrieval is subject to graceful degradation (Marr, 1982; Rumelhart & McClelland, 1986): Unsuccessful attempts at retrieval generally resemble the target, either in

The patterns of semantic errors in speaking and writing are used to constrain claims about the structure of lexical access mechanisms in speech and written language production. It is argued that it is not necessary to postulate a modality-neutral level of lexical representation (lemma) that is intermediate between lexical-semantic representations and modality-specific lexical representations. A dual-stage access model is proposed in which the first stage involves the selection of semantically and syntactically specified, modality-specific lexical forms, and the second stage involves the selection of specific phonological (orthographic) content for the selected lexemes.

In 7 experiments the authors investigated the locus of word frequency effects in speech production. Experiment 1 demonstrated a frequency effect in picture naming that was robust over repetitions. Experiments 2, 3, and 7 excluded contributions from object identification and initiation of articulation. Experiments 4 and 5 investigated whether the effect arises in accessing the syntactic word (lemma) by using a grammatical gender decision task. Although a frequency effect was found, it dissipated under repeated access to a word's gender. Experiment 6 tested whether the robust frequency effect arises in accessing the phonological form (lexeme) by having Ss translate words that produced homophones. Low-frequent homophones behaved like high-frequent controls, inheriting the accessing speed of their high-frequent homophone twins. Because homophones share the lexeme, not the lemma, this suggests a lexeme-level origin of the robust effect. The word frequency effect in speech production was discovered by Oldfield and Wingfield (1965). In a picture-naming task, they found that pictures with low-frequency (LF) names (such as syringe) took longer to name than pictures with high-frequency (HF) names (such as basket). Wingfield (1968)

this article served as partial fulfillment of the requirements for the PhD degree at Rice University for the first author. Preparation of this article was supported in part by National Institute of Health grant number DC 00218 to Rice University. We thank Andrew Shirey for assistance in collecting the data

This article reports 7 experiments investigating whether utterances are planned in a parallel or rightward incremental fashion during language production. The experiments examined the role of linear order, length, frequency, and repetition in producing Dutch verb-particle combinations. On each trial, participants produced 1 utterance out of a set of 3 as quickly as possible. The responses shared part of their form or not. For particle-initial infinitives, facilitation was obtained when the responses shared the particle but not when they shared the verb. For verb-initial imperatives, however, facilitation was obtained for the verbs but not for the particles. The facilitation increased with length, decreased with frequency, and was independent of repetition. A simple rightward incremental model accounts quantitatively for the results. Skilled behavior such as speech production requires advance planning of action components (e.g., Lashley, 1951). In the present paper, I examine what mode the speech production system uses in planning the morphophonological form of an utterance. In particular, I investigate whether the

A series of three experiments investigated semantic and syntactic effects in the production of Adjective+Noun phrases in Dutch. Bilinguals (Dutch native speakers) were presented with English nouns and were asked to produce an Adjective+Noun phrase in Dutch which included the translation of the noun. In two experiments, we blocked items by either semantic category or grammatical gender.We found that participants performed the task slower when the target nouns were of the same semantic category than when they were from different categories; and faster when they were of the same grammatical gender than when they were of different gender. In a final experiment, both manipulations were crossed in order to both replicate the previous experiments and to test for interactions between the two effects. The results of the first two experiments were replicated, and crucially no interaction was found. These findings are compatible with models of lexical retrieval in production in which, first lexico-semantic and lexico-syntactic information are separable; second the flow of activation between the two is feedforward.

This thesis addresses the cognitive basis of syntactic adaptation, which biases speakers to repeat their own syntactic constructions and those of their conversational partners. I address two types of syntactic adaptation: short-term priming and longterm adaptation. I develop two metrics for syntactic adaptation within a speaker and between speakers in dialogue: one for short-term priming effects that decay quickly, and one for long-term adaptation over the course of a dialogue. Both methods estimate adaptation in large datasets consisting of transcribed human-human dialogue annotated with syntactic information. Two such corpora in English are used: Switchboard, a collection of spontaneous phone conversation, and HCRC Map Task, a set of task-oriented dialogues in which participants describe routes on a map to one another. I find both priming and long-term adaptation in both corpora, confirming well-known experimental results (e.g., Bock, 1986b). I extend prior work by showing that syntactic priming effects not only apply to selected syntactic constructions that are alternative realizations of the same semantics, but still hold when a broad

We evaluate the computational model of lexical access proposed by Dell, Schwartz, Martin, Saffran, and Gagnon (1997). They argue that fits of their model to naming data obtained from normals and brain-damaged patients support assumptions regarding interactivity in the lexicon, global damage in aphasia, and continuity between normal and aphasic naming behavior. Our investigation reveals that the model fits the empirical data poorly and that the claims Dell et al. make on the basis of the model's performance would not follow even if the model were accurate. Although we improve the model's fit using a novel automatic regression procedure, it cannot account for five of Dell et al.'s twenty-one patients (24%), and we show that its limitations are inherent in its design. We argue that claims such as those made by Dell et al. can only be addressed by considering evidence from multiple related tasks and by comparing multiple computational models. (Caution: This is a preprint. Ple...

this paper and to Danielle Vignati for preparing statistical analyses of the experimental stimuli

Semantic substitution errors (e.g., saying “arm ” when “leg ” is intended) are among the most common types of errors occurring during spontaneous speech. It has been shown that grammatical gender of German target nouns is preserved in the errors (E. Marx, 1999). In 3 experiments, the authors explored different accounts of the grammatical gender preservation effect in German. In all experiments, semantic substitution errors were induced using a continuous naming paradigm. In Experiment 1, it was found that gender preservation disappeared when speakers produced bare nouns. Gender preservation was found when speakers produced phrases with determiners marked for gender (Experiment 2) but not when the produced determiners were not marked for gender (Experiment 3). These results are discussed in the context of models of lexical retrieval during production. Speaking involves the retrieval of lexical representations that correspond to our intentions and the development of a syntactically and morphophonologically well-formed frame for the sentence to be uttered. The development of such a frame is, in part, guided by syntactic information specific to each word, for example, its grammatical category, subcategorization requirements of verbs, and, for