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PubMed2000

Semantic processing without conscious identification: evidence from event-related potentials.

Three event-related potential (ERP) experiments examined whether semantic content can be accessed from visually presented words that cannot be consciously identified. Category labels were shown to participants, followed by masked, briefly exposed words that were either exemplars of the category or not exemplars. The task was to verify the category, by guessing if necessary, and to identify the word, naming it if possible. Exposure durations were selected to allow identification in approximately half the trials. For identified words, there was a marked difference in the ERP response between in-category and out-of-category words because of an N400 component. For unidentified words, there was a similar although smaller difference. Conscious identification was defined using a variety of approaches: verbal report, 6-alternative forced choice, and binary categorization (in the context of the regression method; A. G. Greenwald, M. R. Klinger, & E. S. Schuh, 1995). By any definition, ERPs for unidentified words showed evidence of semantic processing. In addition, there were differences in the neuronal populations recruited to process above-threshold versus below-threshold words, suggesting qualitative differences.

Adult↗

PubMed1986

Word associations in old age: evidence for consistency in semantic encoding during adulthood.

Word associations of 80 young and 80 older adults were compared for 113 stimulus words. The proportion of paradigmatic responses varied with the grammatical class of the stimulus word and with the vocabulary level of the subject, but not with age. The same proportion of young and older adults gave the most common responses. Although older adults had a greater number of unique responses, this seems to reflect age differences in vocabulary level, as vocabulary but not age was a good predictor. Within-subject variability was also comparable across age, as on a retest young and older adults gave the same proportion of responses that were identical to those on the original test. Both age groups were more likely to repeat common than uncommon responses on the retest. This, together with analyses of response latency, suggests equivalent use of strategic processes across age. The results indicate that semantic structure and semantic encoding in adults are related to verbal ability, but not to age.

Adolescent↗

PubMed1995

Contextual constraint facilitates semantic decisions about object pictures by Alzheimer patients.

Semantic constraints produced by sentence context reduce the time normal adults take to decide whether a given stimulus constitutes a meaningful ending to that sentence. The mechanism responsible for this constraint effect is thought to involve generation of featural restrictions based on context. In the present study, participants heard a sentence whose last word was replaced by an object picture. They decided whether the object formed a sensible ending to that sentence. Contextual constraint present in the sentences greatly influenced decision time: the greater the constraint, the faster the decision. Alzheimer patients were as affected by contextual constraint as were normal adults. The normality of the constraint effect in Alzheimer patients suggests that they can generate featural restrictions and thus retain knowledge of the semantic attributes of objects.

Adult↗

PubMed1996

Methodological control of semantic priming in Alzheimer's disease.

We conducted a lexical-decision, semantic priming experiment that included 250- and 1000-ms stimulus onset asynchronies (SOAs) with 32 probable Alzheimer's disease (AD) and 40 older normal persons. Attention-based, controlled processes are assumed to occur only at the longer of the 2 SOAs. The AD group showed greater than normal priming in the long-SOA but not the short-SOA condition. We conclude that greater than normal AD priming is a function of controlled processing rather than semantic network degradation.

Aged↗

PubMed1991

Automatic semantic priming with various category relations in Alzheimer's disease and normal aging.

The 6 experiments reported here tested the effects of various category relations on automatic semantic priming in 20 Alzheimer's disease (AD), 20 older control, and 22 younger control subjects. The tasks were either word pronunciation or lexical decision; the prime-target stimulus-onset asynchrony (SOA) was always 250 ms. A variety of category relationships between prime and target were examined: highly associated category comembers, subordinate-superordinate or superordinate-subordinate pairs, and pairs selected on the basis of category typically to form typical-typical, atypical-typical, typical-atypical, and atypical-atypical pairings. Both for AD versus older control subjects and for older versus younger control subjects, no significant group differences were found in the magnitude of overall semantic priming or in the effects on priming of factors pertaining to the prime-target relationship.

Adult↗

PubMed2002

Interhemispheric stroop-like interference in number comparison: evidence for strong interhemispheric integration of semantic number information.

Three experiments investigated interhemispheric interactions in number comparison using the interhemispheric Stroop-like paradigm (E. Ratinckx, M. Brysbaert, & B. Reynvoet, 2001). In all experiments, a target was presented in I visual field simultaneously with a distractor in the other visual field. In Experiment 1, both target and distractor were of the same modality (Arabic digits), whereas in Experiment 2, target and distractor were of different modalities (Arabic digits and word numerals). In Experiment 3, the interhemispheric Stroop-like task of Experiment 1 was combined with intrahemispheric conditions to evaluate the strength of the interhemispheric interactions. Overall, the results point to strong interhemispheric integration during semantic access and response preparation with very weak lateralization of the semantic number system.

Adolescent↗

PubMed2006

Parallel distributed processing and lexical-semantic effects in visual word recognition: are a few stages necessary?

D. C. Plaut and J. R. Booth (2000) presented a parallel distributed processing model that purports to simulate human lexical decision performance. This model (and D. C. Plaut, 1995) offers a single mechanism account of the pattern of factor effects on reaction time (RT) between semantic priming, word frequency, and stimulus quality without requiring a stages-of-processing account of additive effects. Three problems are discussed. First, no evidence is provided that this model can discriminate between words and nonwords with the same orthographic structure and still produce the pattern of factor effects on RT it currently claims to produce. Second, the level of representation used by the model to make a lexical decision is inconsistent with what is known about how skilled readers with damage to their semantic system make word/nonword discriminations. Finally, there are a number of results that are difficult to reconcile with the single mechanism account. The authors' preference is to retain the stages-of-processing account.

Humans↗

PubMed2004

Interactive activation in visual word recognition: constraints imposed by the joint effects of spatial attention and semantics.

Two lexical-decision experiments investigated the effects of semantic priming and stimulus intensity when target location varied and was cued by an abrupt onset. In Experiment 1, the spatial cue was a good predictor of target location, and in Experiment 2 it was not. The results indicate that word recognition processes were postponed until spatial attention was focused on the target and that whether attention further affected word recognition depended on cue validity. The joint effects of cue validity and priming interacted when cue validity was high but were additive when cue validity was low. The joint effects of stimulus intensity and semantic priming also varied according to cue validity (i.e., interactive when high and additive when low). The results are discussed in terms of their implications for visual word recognition, the distinction between exogenous and endogenous spatial attention, and how attention is affected by visual word recognition processes.

Attention↗

PubMed2003

Semantic interference from visual object recognition on visual imagery.

A new technique for examining the interaction between visual object recognition and visual imagery is reported. The "image-picture interference" paradigm requires participants to generate and make a response to a mental image of a previously memorized object, while ignoring a simultaneously presented picture distractor. Responses in 2 imagery tasks (making left-right higher spatial judgments and making taller-wider judgments) were longer when the simultaneous picture distractor was categorically related to the target distractor relative to unrelated and neutral target-distractor combinations. In contrast, performance was not influenced in this way when the distractor was a related word, when a semantic categorization decision was made to the target, or when distractor and target were visually but not categorically related to one another. The authors discuss these findings in terms of the semantic representations shared by visual object recognition and visual imagery that mediate performance.

Humans↗

PubMed2003

What do we know about what we cannot remember? Accessing the semantic attributes of words that cannot be recalled.

Two experiments examined access to the semantic attributes of words that participants failed to retrieve. The results indicated access to all 3 dimensions of the semantic differential--evaluation, potency, and activity, as revealed by attribute judgments and by the nature of the commission errors made. There was no evidence for superior access to the emotional-evaluative dimension, inconsistent with what may be expected from the claimed primacy of emotion. In comparison with complete recall, partial recall exhibited a slower rate of forgetting and a stronger tendency to elicit know rather than remember responses. The results were discussed in terms of the processes that lead to partial recall and in terms of the possibility that the affective primacy hypothesis does not apply to memory retrieval.

Adult↗

PubMed2004

Role of grammatical gender and semantics in German word production.

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. Mane, 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.

Adolescent↗

PubMed2004

Semantic ambiguity and the process of generating meaning from print.

An ambiguity disadvantage (slower responses for ambiguous words, e.g., bank, than for unambiguous words) has been reported in semantic tasks (L. R. Gottlob, S. D. Goldinger, G. O. Stone, & G. C. Van Orden, 1999; Y. Hino, S. J. Lupker, & P. M. Pexman, 2002; C. D. Piercey & S. Joordens, 2000) and has been attributed to the meaning activation process. The authors tested an alternative explanation; The ambiguity disadvantage arises from the decision-making process in semantic tasks. The authors examined effects of ambiguity on unrelated trials in a relatedness decision task, because these trials are free from response competition created by ambiguous words on related trials. Results showed no ambiguity effect on unrelated trials (Experiments 2, 3c, and 5c) and an ambiguity disadvantage on related trials (Experiments 3a, 3b, 5a, and 5b).

Cognition↗

PubMed2005

Repeated masked category primes interfere with related exemplars: new evidence for negative semantic priming.

In 4 experiments, the authors found evidence for negatively signed masked semantic priming effects (with category names as primes and exemplars as targets) using a new technique of presenting the masked primes. By rapidly interchanging prime and mask during the stimulus onset asynchrony, they increased the total prime exposure to a level comparable with that of a typical visible prime condition without increasing the number of participants having an awareness of the prime. The negative effect was observed for only low-dominance exemplars and not for high-dominance exemplars. The authors found it using lexical decision (Experiments 1 and 2), lexical decision with a response-window procedure (Experiment 3), and the pronunciation task (Experiment 4). The results are discussed with regard to different theories on semantic priming.

Adult↗

PubMed2005

Semantic and phonological context effects in speech error repair.

When speakers repair speech errors, they plan the repair in the context of an abandoned word (the error) that is usually similar in meaning or form. Two picture-naming experiments tested whether the error's lexical representations influence repair planning. Context pictures were sometimes replaced with target pictures; the picture names were related in meaning or form or were unrelated. The authors measured target picture-naming latencies separately for trials in which the context name was interrupted or completed. Interrupted trials showed semantic interference and phonological facilitation, whereas completed trials showed semantic facilitation and phonological interference. Thus, errors influence repair production. The authors explain the polarity of these effects in terms of the literature on context effects in word production.

Humans↗

PubMed2003

On the use of scaling and clustering in the study of semantic deficits.

In the past decade, several studies have used scaling and clustering techniques to document semantic storage deficits in patients with Alzheimer's disease and in schizophrenia. In this article the authors argued that many of the conclusions drawn from these studies are unjustified by the data. They reviewed the methodology used in these studies and presented data from simulation studies to further investigate the validity of their conclusions. The authors elaborate on the criteria needed to exclude alternative accounts of the data and present empirical data from patients with Alzheimer's disease and normal control participants to demonstrate that analyses of the patients' proximity data do not provide unambiguous evidence for a generalized semantic storage deficit.

Aged↗

PubMed2006

A new dissimilarity measure for finding semantic structure in category fluency data with implications for understanding memory organization in schizophrenia.

The ordering of words in category fluency lists is indicative of the semantic distance between items in conceptual memory. Several studies have concluded from structural analyses of such data, using cluster analysis or multidimensional scaling, that the semantic memory of patients with schizophrenia is more disorganized than that of controls. Previous studies have based their analyses on a measure of average interitem dissimilarity devised by A. S. Chan et al. (1993). Here the authors derive a new and improved method of determining dissimilarity and show that when this measure is applied to the fluency lists of patients with schizophrenia, the average pattern of organization for the animal category has similar structure to that of controls, but with greater variability between individuals.

Adult↗

PubMed1994

Semantic and episodic relations are experimentally dissociable and stochastically independent.

Subjects who studied DOG-BEER and WINE-SWEATER were more likely to recall BEER cued by DOG if they used interactive imagery rather than separate imagery, but the two groups showed no difference in recall of BEER cued by WINE. Recall of BEER cued by WINE was enhanced if BEER and "alcoholic beverages" had been presented before the list was studied, but recall of BEER cued by DOG was unaffected. We conclude that there are two independent types of relation: An episodic relation records the joint occurrence of previously unrelated words; a semantic relation reflects events in one's prior life. The value of a semantic relation is enhanced if the target item is primed in its family; the value of an episodic cue is enhanced by processes that directly encode the occurrence of the two items as a unique event in the life of the subject.

Humans↗

PubMed1993

Context effects in syntactic ambiguity resolution: discourse and semantic influences in parsing reduced relative clauses.

This article examines how certain types of semantic and discourse context affect the processing of relative clauses which are temporarily ambiguous between a relative clause and a main clause (e.g., "The actress selected by the director ..."). We review recent results investigating local semantic context and temporal context, and we present some new data investigating referential contexts. The set of studies demonstrate that, contrary to many recent claims in the literature, all of these types of context can have early effects on syntactic, ambiguity resolution during on-line reading comprehension. These results are discussed within a "constraint-based" framework for ambiguity resolution in which effects of context are determined by the strength and relevance of the contextual constraint and by the availability of the syntactic alternatives.

Adult↗