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Results for “Semantics”

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At least 811 records · Page 45Linked to original sources

PubMed2003

Going beyond the information given: a neural system supporting semantic interpretation.

Relating the meaning of a word to the context in which it is encountered is central to comprehension. We investigated the neural basis of this process. Subjects made decisions based on a semantic property of single nouns. The lack of sentence context created ambiguity, as nouns may have several, unrelated semantic identities. Contrasted with unambiguous decisions about each noun's sound structure, the semantic task resulted in activity in the left superior frontal gyrus (SFG), activity that was dependent on choice reaction time. This identified the left SFG as an executive component of a distributed cognitive system that relates a word's meaning to its semantic context to facilitate comprehension.

Adult↗

PubMed1998

Exploiting the terminological approach from CEN/TC251 and GALEN to support semantic interoperability of healthcare record systems.

We apply the principles included in two CEN standards (ENV 12265, ENV 12264) to the analysis of the semantic structure of health record systems, to support their semantic interoperability. This result was made possible by dramatic methodological progress in the field of terminological systems--due to a worldwide evolution towards a new generation--and by the experience we acquired in the GALEN-IN-USE (formerly GALEN) project. The meaning behind names, content and context of record items and record item complexes can be considered as a 'semantic continuum'. This continuum is made explicit, by building a suitable paraphrase in a controlled language. We can then apply the principles we previously elaborated for the second generation of terminological system. Methodology and tools for generating a controlled language and a second-generation terminological system were developed and successfully used in the GALEN-IN-USE project and promising experiments were performed on elements of record structure listed in LOINC and SDM. In this way, the semantic structures of different record systems can be expressed by the resulting common formalism and thus, information units can be faithfully exchanged among different structures.

Italy↗

PubMed2002

Semantic bias, homograph comprehension, and event-related potentials in schizophrenia.

OBJECTIVES: It is controversial whether a semantic processing bias for strong associates is present in schizophrenia, and unknown whether the language abnormalities observed in schizophrenia can be attributed to dysfunctions early or late in cognitive processing. Combined behavioral and event-related potential (ERP) data can indicate the nature and timing of such abnormalities. METHODS: Sensibility judgements of dominant and subordinate homograph sentences were measured in 12 schizophrenia patients and 13 normal controls. ERPs were recorded to the disambiguating sentence-ending word. RESULTS: All subjects showed greatest misinterpretation of subordinate homograph sentences, but schizophrenia patients particularly misinterpreted these sentence types. For control subjects, subordinate homograph sentences that were classified as nonsensical showed greater N400 than those classified as sensible. By contrast, the N400 of patients was large, regardless of the sensibility judgement--patients' brains initially responded to all subordinate sentences as if nonsensical. These data are consonant with a semantic bias. However, the patients' N400 to dominant homograph sentence endings was also larger than that of controls, a finding not consonant with a semantic bias. CONCLUSIONS: The behavioral results indicate a selective comprehension abnormality in schizophrenia dependent on the content of verbal memory. The ERP results suggest a pervasive contextual memory failure. A semantic activation decay model is proposed to explain these results.

Cognition↗

PubMed2000

EEG brain mapping of phonological and semantic tasks in Italian and German languages.

OBJECTIVES: Event-related potential correlates of phonological encoding - as compared with lexical access and semantic categorization - were measured in two studies involving two groups of 14 German and 14 Italian subjects. METHODS: A two stimulus reaction time paradigm was used. Stimulus pairs presented one-by-one with 2 s inter-stimulus intervals (ISI) had to be matched with respect to lexical identity (word-picture) in a word comprehension task or with respect to the phonological representative of objects in a rhyming task. A semantic categorization task was added for the Italian sample. In both studies, the EEG was recorded from 26 scalp electrodes according to the 10-20 system. The slow negative potential during the ISI (CNV) was determined as the electrocortical correlate of preparation for and activation of the specific language-related task. RESULTS: In both samples, phonological encoding (rhyming) evoked a more pronounced CNV over the left- compared with the right-frontal area, while less lateralized central dominance of the CNV was found in the word comprehension task. Semantic categorization was accompanied by the least asymmetry of activity. CONCLUSIONS: Results indicate that the different degree of asymmetry induced by phonological and semantic processing may be determined from the scalp distribution of slow cortical potentials with cross-lingual reliability.

Acoustic Stimulation↗

PubMed1994

Semantic memory is both impaired and anomalous in schizophrenia.

The integrity of semantic memory in schizophrenia was examined in a reaction time task requiring subjects to verify words as members or non-members of a conceptual category, where the words differed in their degree of semantic relationship to the category. Compared to matched normal controls, 28 schizophrenic patients were impaired on the task, showing slower responses in all conditions. In addition, their performance was anomalous in that they took longest to respond to items that were outside the category but semantically related to it, in contrast to the controls who took the longest to respond to ambiguous words at the borderline of the category. The pattern of 'yes' and 'no' responses of the patients was anomalous in a similar way. In both speed and accuracy of responding, the findings indicate that there is an outward shift of semantic category boundaries in schizophrenia.

Adult↗

PubMed2005

Acquiring the English adjective lexicon: relationships with input properties and adjectival semantic typology.

Properties of the input, such as raw frequency and syntactic diversity, have been shown to play a role, to different extents, in the acquisition of nouns and verbs. This study investigated the relationship between three properties of the input (input frequency, syntactic diversity, and variety in noun-type co-occurrence) and age of acquisition of English adjectives. In addition, this study explored the relationship between adjectival semantic typology and order of acquisition. The data are 7262 child utterances and 6318 maternal utterances containing one of 272 adjective in the language samples of two children, Sarah and Adam, from age 2;3 to 5;0 (Brown, 1973) available in CHILDES (MacWhinney, 2000). Statistical analyses revealed that all three properties of the input were significantly correlated with age of acquisition, but variety in noun-type co-occurrence was not a significant predictor once input frequency and syntactic diversity were taken into account. Semantic analyses revealed that the distribution of adjective types and tokens differed between the children and the mothers (to an extent) when the data were examined in terms of adjectival semantic types. The results suggest that both properties of the input and the semantic properties of the English adjective class play a role in its acquisition.

Child Language↗

PubMed1996

An investigation of semantic space in patients with schizophrenia.

There has been increasing interest in the semantic cognitive system in schizophrenia. Recent findings suggest a possible breakdown of semantic information processing in this disorder. The current study attempts to further examine semantic organization in schizophrenia. Twenty-eight chronic, early-onset schizophrenic patients and 32 controls were matched for premorbid intelligence and compared in their ability to spontaneously cluster exemplars from a specific category during a fluency task. Using multidimensional scaling and clustering techniques, 11 exemplars occurring most frequently in both groups were chosen for examination of their relative "proximity" during word generation. Patients with schizophrenia showed a less stable two-dimensional organization of exemplars and were less likely to group exemplars into subordinate clusters than were normals. These results suggest that semantic networks are disorganized in these patients. These findings may have some implications for the debate over the origin of "thought disorder" in schizophrenia.

Adult↗

PubMed1996

Proactive inhibition and semantic organization: relationship with verbal memory in patients with schizophrenia.

Compared to other cognitive functions in schizophrenia, evidence suggests that verbal memory is particularly impaired. This study used the California Verbal Learning Test (CVLT) to examine proactive inhibition (PI) and semantic processing in verbal memory in 29 patients with schizophrenia and 29 healthy controls. Patients showed significantly less PI, but also did not organize (cluster) their recall according to semantic category. Controls and patients demonstrated small retroactive inhibition (RI) effects regardless of semantic content. Although both groups made similar types and numbers of free recall intrusion errors patients committed more phonemic and nonshared recognition errors. Results suggest that reduced semantic processing prevented build of PI, and contributes to defective memory in schizophrenia. The anatomic-physiologic abnormalities that underlie these findings may be particularly pronounced in prefrontal and temporal-parietal cortical areas.

Adult↗

PubMed2002

Cross-modal semantic priming in schizophrenia.

Work on implicit memory in normal subjects has demonstrated the influence of stimulus modality on the retrieval of semantic information. The present study examined the effects of auditory and visual semantic priming on the recognition of visual words using a lexical decision task. Performance was studied in a group of 20 patients with DSM-IV schizophrenia and 26 normal volunteers of similar age and sex. There were two versions of the task: ipsimodal, in which the word or nonword visual target followed 400 ms after the onset of a visual word prime which may or may not be semantically related to the target; and cross-modal, in which the visual target followed 400 ms after the onset of an auditory word prime. Both groups showed significant priming in both modality conditions, although the schizophrenia patients exhibited significantly greater priming in the cross-modal condition. Priming effects in the ipsimodal condition did not differ substantially between patients and controls. The priming effects in the two conditions correlated with each other in the schizophrenia patients only. The results suggest that priming may occur through amodal semantic representations. In schizophrenia, there appears to be increased cross-modal connectivity (reduced modality modularity and informational encapsulation) between lexical representations that could result in impaired language, particularly speech, processing.

Adult↗

PubMed1999

Instantiation of semantic categories in sentence comprehension by Alzheimer patients.

This study examined whether Alzheimer patients can make elaborative inferences based on the semantic context provided by a sentence. More specifically, if presented with the name of a category in a sentence do they, like normals, infer (instantiate) the particular member of that category most appropriate to the meaning of the sentence (e.g., if a sentence mentions a container of juice, do they infer it is a bottle). Patients were presented with a sentence containing the name of a concrete category. The sense of the sentence was consistent with a low-dominant member of that category. Patients were then shown drawings of four members of that category and asked to select the one appropriate to the sentence. They were later asked to name the drawings. If semantic information is degraded in Alzheimer patients for those objects Alzheimer patients cannot name (as has been claimed), then AD patients should be unable to carry out the type of elaborative semantic inference required to instantiate. Results showed that Alzheimer patients were highly accurate at instantiating even objects they could not name. This is consistent with a relative preservation of semantic knowledge about concrete objects in Alzheimer patients.

Aged↗

PubMed2001

Phonological, semantic, and repetition priming with homophones.

The current study investigated semantic, repetition, and phonological priming using heterographic homonyms (homophones) as stimuli in a lexical decision task. As in previous research, reliable semantic priming and repetition effects were found In addition, the statistical additivity of these two effects was replicated using homophones as stimuli. Using homophones, a reliable phonological priming effect was found when 10-16 intervening trials were used This effect was also statistically independent of semantic priming indicating the independence of the mechanisms responsible for semantic and phonological priming. The magnitude of the phonological priming effect was also significantly less than the magnitude of the repetition effect. This difference in effect magnitude was taken to indicate that the repetition of phonological information is not a primary contributor to the repetition effect.

Adolescent↗

PubMed2001

Loose but normal: a semantic association study.

An abnormal facilitation of the spreading activation within semantic networks is thought to under-lie schizophrenics' remote associations and referential ideas. In normal subjects, elevated magical ideation (MI) has also been associated with a style of thinking similar to that of schizotypal subjects. We thus wondered whether normal subjects with a higher MI score would judge "loose associations" as being more closely related than do subjects with a lower MI score. In two experiments, we investigated whether judgments of the semantic distance between stimulus words varied as a function of MI. In the first experiment, random word pairs of two word classes, animals and fruits, were presented. Subjects had to judge the semantic distance between word pairs. In the second experiment, sets of three words were presented, consisting of a pair of indirectly related, or unrelated nouns plus a third noun. Subjects had to judge the semantic distance of the third noun to the word pair The results of both experiments showed that higher MI subjects considered unrelated words as more closely associated than did lower MI subjects. We conjecture that for normal subjects high on MI "loose associations" may not be loose after all. We also note that the tendency to link uncommon, nonobvious, percepts may not only be the basis of paranormal and paranoid ideas of reference, but also a prerequisite of creative thinking.

Adult↗

PubMed2002

Brain activity during syntactic and semantic processing--a magnetoencephalographic study.

Drawings of objects were presented in series of 54 each to 14 German speaking subjects with the tasks to indicate by button presses a) whether the grammatical gender of an object name was masculine ("der") or feminine ("die") and b) whether the depicted object was man-made or nature-made. The magnetoencephalogram (MEG) was recorded with a whole-head neuromagnetometer and task-specific patterns of brain activity were determined in the source space (Minimum Norm Estimates, MNE). A left-temporal focus of activity 150-275 ms after stimulus onset in the gender decision compared to the semantic classification task was discussed as indicating the retrieval of syntactic information, while a more expanded left hemispheric activity in the gender relative to the semantic task 300-625 ms after stimulus onset was discussed as indicating phonological encoding. A predominance of activity in the semantic task was observed over right fronto-central region 150-225 ms after stimulus-onset, suggesting that semantic and syntactic processes are prominent in this stage of lexical selection.

Adult↗

PubMed1997

Effects and limitations of prosodic and semantic biases on syntactic disambiguation.

This paper examined the effects of prosody on the syntactic ambiguity resolution of Japanese sentences, especially with reference to the interaction with semantic bias. Syntactically ambiguous sentences with different types of semantic bias were constructed. The degree of bias in each sentence was evaluated through visual presentation experiments. Three types of sentences were selected based on the results of visual presentation experiments, were recorded with prosody maximally favoring each possible interpretation of the sentences, and were used as the stimuli for the auditory presentation experiments. The results showed that prosodic cues can influence the interpretation of a sentence even when the sentence is strongly semantically biased. The results also showed a limitation to prosodic cues. The prosodic biases alone were not sufficient to fully determine the interpretation of the sentences even when the sentences were neutrally biased semantically.

Humans↗

PubMed2003

Visual object recognition in early Alzheimer's disease: deficits in semantic processing.

OBJECTIVES: The purpose of the present study was to divide visual object recognition into different stages and to reveal which of these stages are impaired in early Alzheimer's disease (AD). METHODS: Performance in object detection, familiarity detection, semantic name and word categorization, and identification with naming were studied by using two-choice reaction-time tasks. Ten patients with newly diagnosed AD and 14 healthy subjects were studied. RESULTS: Patients with early AD had impairments in several stages of the object recognition process. After controlling for the basic visuomotor slowness, they were as fast and as accurate as the controls in object detection, but had difficulties in all stages that required semantic processing. CONCLUSIONS: Semantic memory impairments contribute to the deficits in visual object recognition in early AD. Thus, the semantic memory deficit may be manifested in several ways in the difficulties that AD patients experience in everyday life.

Aged↗

PubMed2000

Aberrant semantic and affective processing in people at risk for psychosis.

Semantic and affective processing were examined in people at risk for psychosis. The participants were 3 groups of college students: 41 people with elevated Perceptual Aberration and Magical Ideation (PerMag) scores, 18 people with elevated Social Anhedonia (SocAnh) scores, and 100 control participants. Participants completed a single-word, continuous presentation pronunciation task that included semantically related words, affectively valenced words, and semantically unrelated and affectively neutral words. PerMag participants exhibited increased semantic priming and increased sensitivity to affectively valenced primes. SocAnh participants had increased sensitivity to affectively valenced targets.

Adolescent↗

PubMed1989

Semantic and perceptual priming: how similar are the underlying mechanisms?

Both semantic priming and perceptual priming consist of facilitation of the identification of primed stimuli and inhibition of the identification of nonprimed stimuli. The similarities between the two phenomena suggest that a common attentional mechanism underlies both, and this has been explicitly proposed by several attention theorists. In this article it is argued that the phenomena of semantic and perceptual priming are qualitatively different, perceptual priming reflecting a sensitivity change in the recognition process brought about by attention, and semantic priming reflecting a bias change in the recognition process brought about by attention. Because different mechanisms are required to produce sensitivity and bias changes, this implies that the attentional mechanisms responsible for semantic and perceptual priming are distinct. In terms of recent discussions of the modularity versus the unity of cognitive architecture, the present conclusion supports a modular architecture for attentional processes.

Attention↗

PubMed1996

Semantic and spatial components of selective attention.

Semantic and spatial effects on selective processing were examined. A prime presented 250 ms or 1,000 ms before a pair of masked words was related to 1 of the words on 1/3 of the trials. Although Experiments 1 and 2 required report of both words, processing was selective; typically, just 1 word could be reported. In Experiment 1, reported words were more often top words, showing spatial selectivity, and more often words related to the prime, showing semantic selectivity. Experiment 2 included to-be-ignored peripheral cues 50 ms before the pair. Related words were reported more often at both delays, and cuing produced an additive benefit at 1,000 ms. Experiment 3 required report of just the cued word and included 100-ms cues. Cued words were reported more often, especially at 1,000 ms and with 100-ms cues, but semantic selectivity also occurred. Selectivity via semantic priming and via location reflect separate attentional mechanisms.

Attention↗