Dataset Information

Evidence of semantic clustering in letter-cued word retrieval.

ABSTRACT: Letter-cued word fluency is conceptualized as a phonemically guided word retrieval process. Accordingly, word clusters typically are defined solely by their phonemic similarity. We investigated semantic clustering in two letter-cued (P and S) word fluency task performances by 315 healthy adults, each for 1 min. Singular value decomposition (SVD) and generalized topological overlap measure (GTOM) were applied to verbal outputs to conservatively extract clusters of high-frequency words. The results generally confirmed phonemic clustering. However, we also found considerable semantic/associative clusters of words (e.g., pen, pencil, and paper), and some words showed both phonemic and semantic associations within a single cluster (e.g., pair, pear, peach). We conclude that letter-cued fluency is not necessarily a purely phonemic word retrieval process. Strong automatic semantic activation mechanisms play an important role in letter-cued lexical retrieval. Theoretical conceptualizations of the word retrieval process with phonemic cues may also need to be reexamined in light of these analyses.

SUBMITTER: Sung K

PROVIDER: S-EPMC4227503 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Evidence of semantic clustering in letter-cued word retrieval.

Sung Kyongje K Gordon Barry B Yang Sujeong S Schretlen David J DJ

Journal of clinical and experimental neuropsychology 20131018 10

Letter-cued word fluency is conceptualized as a phonemically guided word retrieval process. Accordingly, word clusters typically are defined solely by their phonemic similarity. We investigated semantic clustering in two letter-cued (P and S) word fluency task performances by 315 healthy adults, each for 1 min. Singular value decomposition (SVD) and generalized topological overlap measure (GTOM) were applied to verbal outputs to conservatively extract clusters of high-frequency words. The result ...[more]

PMID: 24134125

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Project description:BackgroundAbnormal storage and/or access are among the hypothesized causes of semantic memory deficit in schizophrenia. Neuropsychological and connectionist models have emphasized functional systems that serve the processing of word meaning and frequency: semantic storage disturbance is presumed to result from weak representations of word meaning; defective access is assumed to result from compromises to pathways that activate word frequency knowledge. Candidate biological systems include neuromodulatory pathways that normally function to enhance neural signals (e.g., cholinergic system). Electrophysiological responding may be informative regarding the storage-access distinction for schizophrenia.MethodsVisual event-related potentials were recorded for 14 schizophrenia outpatients receiving atypical antipsychotics, and 14 healthy controls group-matched to patients on age, gender, and demographics. N400 was elicited using an incidental semantic priming paradigm, in which semantic relatedness and word frequency were varied, and a letter probe task.ResultsCompared to controls, patients showed reduced N400 (microV) discrimination of semantic relatedness. Groups also showed different patterns of N400 to word frequency. Controls' N400 increased in negativity as words decreased in frequency of occurrence, while patients did not show a linear relationship between N400 and word frequency. Groups also differed for N400 to frequently occurring words. Patients exhibited increased negativity to high and very high frequency words, compared to controls. A subgroup of patients receiving antipsychotics with known affinity binding for muscarinic receptors (clozapine and olanzapine) showed significant albeit limited N400 priming, but their N400 to word frequency remained nonsignificant.ConclusionsResults suggest a deficit in semantic access for schizophrenia, as well as an influence of neuromodulators on the activation of connections among semantic representations. Cumulative findings indicating only limited N400 priming for patients receiving either typical or atypical antipsychotics support the hypothesis that semantic memory deficit represents a trait marker for schizophrenia.

Dataset Information

Evidence of semantic clustering in letter-cued word retrieval.

Publications

Evidence of semantic clustering in letter-cued word retrieval.

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