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PubMed2001

Modulating semantic feedback in visual word recognition.

According to the interactive activation framework proposed by McClelland and Rumelhart (1981), activation spreads both forward and backward between some levels of representation during visual word recognition. An important boundary condition, however, is that the spread of activation from lower to higher levels can be prevented (e.g., explicit letter processing during prime processing eliminates the well-documented semantic priming effect). Can the spread of activation from higher to lower levels also be prevented? This question was addressed with a choice task procedure in which subjects read a prime word and then responded to a target, performing either lexical decision or letter search depending on the color of the target. A semantic context effect was observed in lexical decision, providing evidence of semantic-level activation. In contrast, there was no semantic context effect in the letter search task, despite evidence of lexical involvement: Words were searched faster than nonwords. Further evidence of lexical involvement in the letter search task appeared in Experiment 2 in the form of greater identity priming for words than for nonwords. The results of these experiments are consistent with the conclusion that feedback from the semantic level to the lexical level can be blocked. Hence, between-level activation blocks can be instantiated in both bottom-up and top-down directions.

Adult↗

PubMed2002

The impact of feedback semantics in visual word recognition: number-of-features effects in lexical decision and naming tasks.

The notion of feedback activation from semantics to both orthography and phonology has recently been used to explain a number of semantic effects in visual word recognition, including polysemy effects (Hino & Lupker, 1996; Pexman & Lupker, 1999) and synonym effects (Pecher, 2001). In the present research, we tested an account based on feedback activation by investigating a new semantic variable: number of features (NOF). Words with high NOF (e.g., LION) should activate richer semantic representations than do words with low NOF (e.g., LIME). As a result, the feedback activation from semantics to orthographic and phonological representations should be greater for high-NOF words, which should produce superior lexical decision task (LDT) and naming task performance. The predicted facilitory NOF effects were observed in both LDT and naming.

Decision Making↗

PubMed1996

Cross-language facilitation, semantic blindness, and the relation between language and memory: a reply to Altarriba and Soltano.

This comment corrects some inaccuracies, points to some methodological problems, and makes three substantive observations regarding the Altarriba and Soltano (1996) article. First, token individuation theory does not explain what is new and interesting in the Altarriba and Soltano data, namely cross-language semantic facilitation in lists and a list-sentence effect, that is, a large difference in the effect of semantic repetition when identical translation equivalents occurred in sentences versus lists. Second, Altarriba and Soltano's small and nonsignificant semantic blindness effect for translation equivalents in split-language sentences is attributable to the peculiar nature of their materials, procedures, analyses, and experimental design. These problems nullify their conclusion that semantic blindness does not occur, and we discuss several clear cases where semantic blindness has been demonstrated. Finally, we suggest an explanation for Altarriba and Soltano's unexplained effects (cross-language facilitation and the list-sentence effect) and show why these effects are important for the general issue of relations between language and memory.

Humans↗

PubMed1997

Semantic satiation in healthy young and older adults.

In four experiments, semantic satiation was investigated in young and old adults. In the first two experiments, subjects were repeatedly presented a word (e.g., DOG) and then were presented a pair of words (e.g., DOG-CAT or DOG-CHAIR) for a relatedness decision. The results of both experiments indicated that for the young adults, the relatedness effect (the difference between response latency on related and unrelated trials) decreased as a function of the number of times the satiated word was repeated, whereas for the older adults, there was no evidence of a decrease in the relatedness effect across repetitions of the satiated word. In the third experiment, we investigated whether phonological codes are also susceptible to satiation. This experiment was similar to the first two experiments with the exception that subjects made rhyme decisions (SAME-CLAIM VS. SAME-DIME) instead of semantic relatedness decisions. The results of this experiment did not yield any evidence of satiation for either the young adults or the older adults. The final experiment eliminated a simple decrease in attentional alertness or fatigue account of the semantic satiation effects found in the first two experiments. In this experiment, the repeated word was always unrelated to the pair of words presented for the relatedness decision. The results of this experiment did not yield any evidence of semantic satiation for either the young or the older adults. The discussion focuses on the mechanisms underlying semantic satiation and the implications of age-related changes in these mechanisms.

Adolescent↗

PubMed2000

On the interaction between linguistic and pictorial systems in the absence of semantic mediation: evidence from a priming paradigm.

Use of the letter search task in the context of the priming paradigm has proved to be an invaluable tool for the investigation of the strategic control of processes involved in word recognition. In particular, previous findings that letter search on a prime word interferes with the priming of semantically/associatively related targets, but not with the priming of either identical or morphologically related targets, suggests that letter search may selectively interfere with semantic processing, leaving other levels of processing intact. In the present experiments, this investigation was extended by exploring the priming of pictures following letter search of either a same-concept word (repetition priming) or a semantically/associatively related word (semantic priming). There was significant repetition priming of picture categorization following both silent reading and letter search of the prime word (Experiments 1 and 2). In contrast, semantic priming of pictures was found only following silent reading of the prime; there was no semantic priming following letter search of the prime (Experiment 2). This pattern of results suggests that focusing attention at the letter level during prime processing selectively attenuates activation of the semantic system by the prime. It does not prevent the spread of activation between the lexical and pictogen levels of representation of a given concept.

Humans↗

PubMed1988

[Do phonological and semantic processings of Kanji finish at the same time?].

Two experiments were designed based on Neisser's visual searching paradigm to compare visual, phonological and semantic processing times of two-character compound Kanji, the Japanese logographic script. In Exp. 1, four undergraduates were asked to scan 10-word lists visually, phonologically or semantically according to the task required to find out a target which is either identical with or similar to the word previously presented at the trial. The results indicated that visual processing is quickest, and phonological and semantic processing finish at the same time. In Exp. 2, two- and four-syllable words were used as stimuli. Five undergraduates' results suggested that the length of syllable has effect on neither phonological nor semantic processing time, and replicated the results of Exp. 1 suggesting that phonological and semantic processing finish at the same time.

Adult↗

PubMed2005

[An influence of flanker in a category verification task on semantic satiation effect].

This study examined semantic satiation in a flanked-category verification task. In the experiment, a target pair (FRUIT grape) was flanked by a distractor (i.e., flanker). There were three conditions; compatible condition in which flankers were semantically related to a target category word (FRUIT grape vs. apple), incompatible condition in which flankers were not related (FRUIT grape vs. coffee), baseline condition in which flankers were not presented. Seventy-three college students participated in the experiment and judged whether or not a instance word was related to a category word in the target pair. As a result, the semantic satiation effect was found regardless of flanker conditions. Additionally, the influence of flanker was not attenuated by prime repetitions. These results were elucidated in terms of decision criterion based on a semantic relatedness of prime and target instance words. A possibility indicated that the locus of decision criteria was shifted to a more careful one by prolonged prime repetitions. Finally, one explanation was discussed that an influence of satiation would be emerged from the process which suited semantic information to the context.

Adult↗

PubMed1998

Towards semantic integration within an existing medical information system.

Talking about the problems of integration in medical information systems, the necessity to provide end users with a consistent and coherent view of patient's data, has been largely reported. In order to attempt this goal, systems need to perform semantic integration. We propose a pragmatic way to describe the semantics of the elements of a database, based on a bottom-up three steps process: 1. a back documentation of the elements of the system from their description contained in the data catalog of the database 2. a first semantic extension to transform a data catalog into a data dictionary 3. a second semantic extension to create a dictionary of the medical concepts from a data dictionary. This dictionary of concepts can be considered as the final result of "semantic integration". It contains a set of entities directly understandable by the end users. These entities are deduced or built from the elements collected and characterized in the data dictionary. This work reports the conceptual analysis and the implementation of such a data dictionary.

Database Management Systems↗

PubMed1999

Semantic processing deficits in patients with Parkinson's disease: degraded representation or defective retrieval?

OBJECTIVE: To determine whether degraded representations (characterized by small differences between word sense frequencies), or defective competitive processes (high levels of word sense lateral inhibition), individually or jointly, can give rise to parkinsonian semantic deficits. DESIGN: Computer model of semantic processing. OUTCOME MEASURES: Correct sense selection, defined by the activation of the word sense unit that first reaches the 0.5 activation threshold. If Parkinson disease (PD)-like errors are observed only at high levels of lateral inhibition, independently of low or high sense frequency deltas (SFDs), this would indicate that a defective competitive process alone could account for the errors. Alternatively, if PD-like errors were observed at any level of lateral inhibition, exclusively with low SFD words, this would indicate that degraded representations alone could account for the errors. RESULTS: Neither degraded representations nor defective competitive processes alone can account for parkinsonian semantic errors. An interaction between the 2, however, correctly reproduces both increased errors and longer latency responses. CONCLUSIONS: Competing explanations for semantic deficits in patients with Parkinson's disease need to be integrated in order to develop effective interventions (e.g., estimating the amount of context required to improve semantic processing performance).

Humans↗

PubMed1999

Representing genomic knowledge in the UMLS semantic network.

Genomics research has a significant impact on the understanding and treatment of human hereditary diseases, and biomedical literature concerning the genome project is becoming more and more important for clinicians. The Unified Medical Language System (UMLS) is designed to facilitate the retrieval and integration of information from multiple-readable biomedical information resources. This paper describes our efforts to integrate concepts important to genomics research with the UMLS semantic network. We found that the UMLS contains over 30 semantic types and most of the semantic relations that are essential for representing the underlying genomic knowledge. In addition, we observed that the organization of the network was appropriate for representing the hierarchical organization of the concepts. Because some of the concepts critical to the genomic domain were found to be missing, we propose to extend the network by adding six new semantic types and sixteen new semantic relations.

Genome, Human↗

PubMed2000

Dual access to semantics in autism: is pictorial access superior to verbal access?

The main aim of the present study was to compare pictures and words with respect to access to semantic systems in autism using a semantic priming paradigm. A word completion task was conducted using both within-modality (word word, WW) and cross-modality (picture word, PW) conditions on a group of high-functioning adolescents and adults with autism (N = 20) and a control group (N = 20) matched on chronological age, mental age, Verbal IQ and Performance IQ. Both groups showed semantic priming effects in both modality conditions. generating significantly more responses for related prime-target pairs than for unrelated pairs. Although the control group performed similarly on both priming tasks, the autistic group performed significantly better on a PW task than on a WW task. These findings suggest the possible advantage of pictures over words in access to semantics in autism. The theoretical implications are discussed in terms of functional asymmetry between verbal and pictorial semantic operations that may be specific to autism.

Adolescent↗

PubMed2001

Meaning and modality: influences of context, semantic memory organization, and perceptual predictability on picture processing.

Using event-related potentials (ERPs), the authors investigated the influences of sentence context, semantic memory organization, and perceptual predictability on picture processing. Participants read pairs of highly or weakly constraining sentences that ended with (a) the expected item, (b) an unexpected item from the expected semantic category, or (c) an unexpected item from an unexpected category. Pictures were unfamiliar in Experiment 1 but preexposed in Experiment 2. ERPs to pictures reflected both contextual fit and memory organization, as do ERPs to words in the same contexts (K. D. Federmeier & M. Kutas, 1999). However, different response patterns were observed to pictures than to words. Some of these arose from perceptual predictability differences, whereas others seem to reflect true modality-based differences in semantic feature activation. Although words and pictures may share semantic memory, the authors' results show that semantic processing is not amodal.

Adult↗

PubMed2001

Heterogeneity of semantic and visuospatial deficits in early Alzheimer's disease.

Staging of visuospatial and semantic deficits in patients with dementia of the Alzheimer type (DAT) was examined. The authors hypothesized that semantic ability would be more impaired in these patients, reflecting predominant temporal pathology early in the disease. However, in the 1st study (n = 26), 3 patients (11.5%) had marked visual but no semantic impairment. This finding was extended in a 2nd study with a 2nd patient sample (n = 21) and more specific tasks. Two patients (9.5%) again had visual but no semantic impairment. These studies confirm that, in patients with DAT presenting with relatively focal deficits, visual deficits sometimes occur before semantic problems. The findings are discussed with regard to the cognitive demands and neuroanatomical underpinning of the tests used and point to the necessity of using cognitively specific tests to enable accurate analysis of deficits in the context of the neuroanatomical basis of impairment.

Age Factors↗

PubMed2001

Aggregating UMLS semantic types for reducing conceptual complexity.

The conceptual complexity of a domain can make it difficult for users of information systems to comprehend and interact with the knowledge embedded in those systems. The Unified Medical Language System (UMLS) currently integrates over 730,000 biomedical concepts from more than fifty biomedical vocabularies. The UMLS semantic network reduces the complexity of this construct by grouping concepts according to the semantic types that have been assigned to them. For certain purposes, however, an even smaller and coarser-grained set of semantic type groupings may be desirable. In this paper, we discuss our approach to creating such a set. We present six basic principles, and then apply those principles in aggregating the existing 134 semantic types into a set of 15 groupings. We present some of the difficulties we encountered and the consequences of the decisions we have made. We discuss some possible uses of the semantic groups, and we conclude with implications for future work.

Semantics↗

PubMed2002

[Variability of right hemisphere activation during semantic word processing in aphasic patients: an electrophysiologic study in three patients].

After stroke, the interhemispheric reorganisation of the neural network implicated in language is hypothesized to be a function not only of the site of lesion but also of the residual impairment. With a multiple case approach, we tested this hypothesis in three chronic aphasic patients. Two patients, GE (capsulo-lenticular stroke) and JHN (fronto-temporal stroke) showed formal residual semantic difficulties, while the third patient (EG, large sylvian lesion) did not. Brain electric activity was analysed during a categorisation task of tachistoscopically presented words in the left and the right visual field. The temporal analysis of brain activity showed that both patients with semantic residual difficulties activated the right hemisphere (RH) during some steps of word processing. In the third patient, without semantic impairment, the RH was activated only during a short time period. Further more, RH activation was shown to be dependent on the visual field of word presentation. Phonological impairment was not predictive of RH activation. These results suggest that RH activation, particularly anterior regions, can occur during semantic processing of words as a function of semantic residual impairment.

Adult↗

PubMedDate not supplied

[The semantic memory deficit in Alzheimer's disease].

INTRODUCTION AND DEVELOPMENT: Although the loss of episodic memory is considered one of the the hallmarks of Alzheimer s disease (AD), it is by no means the only memory dysfunction suffered by these patients. Perhaps equally important in terms of functional adaptation is the loss of, what Tulving referred, semantic memory. Semantic memory is that information necessary for language, a mental diccionary including not only lexical information (i.e., word meaning and concepts) but also facts and general world knowledge. There is a debate in the field of cognitive psychology regarding semantic memory, deficits in AD; whether there is an actual defect in semantic memory, or this is related to a disruption of the information accessing process. Neuroimaging studies have shown that the basis of the semantic memory defect is localized in the temporal and frontal lobes. CONCLUSIONS: The inferior temporal lobe, and perhaps more importantly, the parahippocampal gyrus, is critical for the ability to successfully name objects. However, the ability to retrieve name of objects appears to be associated with the frontal lobes.

Alzheimer Disease↗

PubMed2003

Relating UMLS semantic types and task-based ontology to computer-interpretable clinical practice guidelines.

Medical knowledge in clinical practice guideline (GL) texts is the source of task-based computer-interpretable clinical guideline models (CIGMs). We have used Unified Medical Language System (UMLS) semantic types (STs) to understand the percentage of GL text which belongs to a particular ST. We also use UMLS semantic network together with the CIGM-specific ontology to derive a semantic meaning behind the GL text. In order to achieve this objective, we took nine GL texts from the National Guideline Clearinghouse (NGC) and marked up the text dealing with a particular ST. The STs we took into consideration were restricted taking into account the requirements of a task-based CIGM. We used DARPA Agent Markup Language and Ontology Inference Layer (DAML + OIL) to create the UMLS and CIGM specific semantic network. For the latter, as a bench test, we used the 1999 WHO-International Society of Hypertension Guidelines for the Management of Hypertension. We took into consideration the UMLS STs closest to the clinical tasks. The percentage of the GL text dealing with the ST "Health Care Activity" and subtypes "Laboratory Procedure", "Diagnostic Procedure" and "Therapeutic or Preventive Procedure" were measured. The parts of text belonging to other STs or comments were separated. A mapping of terms belonging to other STs was done to the STs under "HCA" for representation in DAML + OIL. As a result, we found that the three STs under "HCA" were the predominant STs present in the GL text. In cases where the terms of related STs existed, they were mapped into one of the three STs. The DAML + OIL representation was able to describe the hierarchy in task-based CIGMs. To conclude, we understood that the three STs could be used to represent the semantic network of the task-bases CIGMs. We identified some mapping operators which could be used for the mapping of other STs into these.

Humans↗

PubMed2003

Integrating a hypernymic proposition interpreter into a semantic processor for biomedical texts.

Semantic processing provides the potential for producing high quality results in natural language processing (NLP) applications in the biomedical domain. In this paper, we address a specific semantic phenomenon, the hypernymic proposition, and concentrate on integrating the interpretation of such predications into a more general semantic processor in order to improve overall accuracy. A preliminary evaluation assesses the contribution of hypernymic propositions in providing more specific semantic predications and thus improving effectiveness in retrieving treatment propositions in MEDLINE abstracts. Finally, we discuss the generalization of this methodology to additional semantic propositions as well as other types of biomedical texts.

Abstracting and Indexing↗