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PubMed1983

Binocular rivalry and semantic processing: out of sight, out of mind.

Previous studies of binocular rivalry have shown that some aspects of a phenomenally suppressed stimulus remain available for visual analysis. The question remains, however, whether this analysis extends to the case of semantic information. This experiment examines that question using a semantic-priming paradigm in which prime words were briefly flashed to an eye during either dominance or suppression phases of binocular rivalry. Reaction times on a lexical-decision task were significantly shortened (the semantic-priming effect) only when prime words were presented to an eye during dominance; suppression acted to impair word recognition and to eliminate semantic priming. These results are inconsistent with certain cognitive models of binocular rivalry.

Cognition↗

PubMed1987

Structure and process in semantic memory: new evidence based on speed-accuracy decomposition.

Reaction-time and accuracy data obtained from studies of sentence verification have not been rich enough to answer certain important theoretical questions about structures and processes in human semantic memory. However, a new technique called speed-accuracy decomposition (Meyer, Irwin, Osman, & Kounios, 1986) may help solve this problem. The technique allows intermediate products of sentence verification to be analyzed more precisely. Three experiments with speed-accuracy decomposition indicate that verification processes produce useful partial information before they are completed. Such information appears to accumulate continuously at a rate whose magnitude depends on the degree of relatedness between semantic categories. This outcome is consistent with continuous computational (e.g., semantic-feature comparison) models of semantic memory. An analysis of reaction-time minima suggests that a discrete all-or-none search process may also contribute at least occasionally to sentence verification. Further details regarding the nature of these processes and the memory structures on which they operate can be inferred from additional results obtained through speed-accuracy decomposition.

Humans↗

PubMed1990

Adding new information to semantic memory: how much learning is enough to produce automatic priming?

A series of experiments investigated the integration of new vocabulary words into semantic memory and the creation of new associations between preexisting, but previously unrelated, words. The ability of the newly learned vocabulary words and associations to facilitate lexical decisions when serving as primes under conditions associated with automatic processing was used to index integration. The results indicate that very extensive study is necessary for such integration to occur and that it is easier to add a new word to semantic memory than to establish a link between two formerly unconnected words already in semantic memory. The implications of these results for models of semantic memory and the episodic/semantic distinction are considered.

Adult↗

PubMed1999

Time course of word identification and semantic integration in spoken language.

The minimum duration signal necessary to identify a set of spoken words was established by the gating technique; most words could be identified before their acoustic offset. Gated words were used as congruous and incongruous sentence completions, and isolation points established in the gating experiment were compared with the time course of semantic integration evident in event-related brain potentials. Differential N400 responses to contextually appropriate and inappropriate words were observed about 200 ms before the isolation point. Semantic processing was evident before the acoustic signal was sufficient to identify the words uniquely. Results indicate that semantic integration can begin to operate with only partial, incomplete information about word identity. Influences of semantic constraint, word frequency, and rate of presentation are described.

Adolescent↗

PubMed2002

Semantic and syntactic forces in noun phrase production.

Three experiments investigated semantic and syntactic effects in the production of phrases in Dutch. Bilingual participants were presented with English nouns and were asked to produce an adjective + noun phrase in Dutch including the translation of the noun. In 2 experiments, the authors blocked items by either semantic category or grammatical gender. 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 the target nouns had the same gender than when they had different genders. In a final experiment, both manipulations were crossed. The authors replicated the results of the first 2 experiments, and no interaction was found. These findings suggest a feedforward flow of activation between lexico-semantic and lexico-syntactic information.

Adult↗

PubMed1986

Use of semantic context by patients with Alzheimer's disease.

In this study we used semantic-priming procedures to examine limitations in the use of semantic context by patients with Alzheimer's disease. We also tried to determine whether any such contextual effects were mediated solely through automatic processes or whether attentional processes were also involved. Three tasks were applied to examine the effect of semantic context on the performance of 18 normal elderly and 18 normal young subjects, and on 18 patients with Alzheimer's disease. When normal and demented subjects were asked to decide whether a given item was a member of a certain category, results showed that their response times were equally affected by the item's dominance in the category. The time that demented patients took to recognize a word was actually affected more by the semantic context provided by a priming sentence than was that of normal subjects. When asked to generate the final word of an incomplete sentence, demented subjects performed very poorly unless potential responses were highly constrained by sentence context.

Adult↗

PubMed2002

Asymmetric aging effects on semantic and phonological processes: naming in the picture-word interference task.

In 2 experiments, participants named pictures while ignoring auditory word distractors. For pictures with homophone names (e.g., ball), distractors semantically related to the nondepicted meaning (e.g., prom) facilitated naming by top-down phonological connections for young but not for older adults. Slowing from unrelated distractors and facilitation from phonologically related distractors were age invariant except in distractors that were both semantically and phonologically related. Only distractors semantically related to the picture interfered more for older than younger adults. These results ar einconsistent with age-linked deficits in inhibition of irrelevant information from either internal or external sources. Rather, aging affects priming transmission in a connectionist network with asymmetric effects on semantic and phonological connections involved in comprehension and production, respectively.

Adolescent↗

PubMed1993

Age-related slowing and the time course of semantic priming in visual word identification.

In 4 experiments, the authors investigated the time course of semantic priming effects during 2 forms of visual word identification, lexical decision and pronunciation. On each trial, a target letter string was preceded by a single-word priming context. The effects of varying the stimulus onset asynchrony between the prime and the target indicated that the time course of semantic priming was equivalent for young and older adults. There were no consistent differences between lexical decision and pronunciation in the time course of semantic priming. The age differences associated with response selection were greater than would be predicted by generalized age-related slowing. The semantic priming effects were also inconsistent with a generalized slowing model, but the reliability of these effects was substantially lower than the reliability of the other task-related variables.

Adolescent↗

PubMed1998

Semantic memory in Alzheimer's disease: representativeness, ontologic category, and material.

Alzheimer's disease (AD) patients with semantic memory difficulty and AD patients with relatively preserved semantic memory named pictures and judged the category membership of words and pictures of natural kinds and manufactured artifacts that varied in their representativeness. Only semantically impaired patients were insensitive to representativeness in their category judgments. AD subgroup judgments did not differ for natural kinds compared to manufactured artifacts nor for words compared to pictures. AD subgroup differences could not be explained by dementia severity, memory, reading, and visuoperception. The similarity process for relating coordinate members of a taxonomic category contributes to the normal appreciation of word and picture meaning, and this process is compromised in AD patients with semantic difficulty.

Aged↗

PubMed1998

Evidence for an impaired ability to determine semantic relations in Alzheimer's disease patients.

An important feature of Alzheimer's disease (AD) that differentiates it from normal aging is the deterioration of semantic memory. The purpose of this study was to determine if the poor performance of AD patients on tasks that require them to use semantic memory is related to their inability to identify specific semantic relations. This hypothesis was tested by comparing the reaction times and error rates of AD patients to those of the normal elderly and normal young in a sentence verification task. We found that AD patients were significantly slower and less accurate than the normal elderly and the young on aspects of the task that required the knowledge of specific semantic relationships. In a 2nd experiment, young normal participants performed the same task with a concurrent memory load. The results from Experiment 2 indicate that the performance of AD patients in this task cannot be attributed to a diminished working memory capacity.

Adult↗

PubMed1999

Spatial and semantic inhibitory processing in schizophrenia.

Two experiments assessed inhibitory mechanisms associated with the posterior and anterior attention networks in schizophrenia. Experiment 1 assessed the inhibition of return effect of the posterior network. Both healthy adults and schizophrenic adults showed inhibition of return, suggesting that this inhibitory mechanism of visual orienting is preserved in schizophrenia. Experiment 2 assessed semantic inhibition, which supposedly taps the anterior network, in a lexical-decision task. Healthy adults showed semantic inhibition effects in both visual fields. Schizophrenic adults showed semantic inhibition effects when targets were presented to the left visual field, involving the right hemisphere. However, semantic facilitation rather than inhibition was observed when targets were presented to the right visual field, involving the left hemisphere. These results reflect left hemisphere dysfunction associated with deficits in attentional control in schizophrenia.

Adult↗

PubMed2004

Selection ability in Alzheimer's disease: investigation of a component of semantic processing.

Selection ability (selecting a response from several competing semantic and/or lexical representations) was tested in 21 participants with Alzheimer's disease (AD) and 28 control participants to help clarify the nature of semantic impairments in AD. Selection demands were manipulated in 3 tasks (lexical fluency, comparison, and verb generation). In each, high-selection conditions required response selection from competing alternatives, whereas low-selection conditions had a reduced need for selection. Patients with AD were disproportionately impaired on the high-selection conditions of all tasks, even when this condition was easier. Selection deficits on verb generation were evident only relative to nonspeeded controls. Overall results indicate impaired semantic selection abilities in AD, which may contribute to poor performance on some semantic tasks.

Aged↗

PubMed2007

Reversal of the concreteness effect for verbs in patients with semantic dementia.

The authors assessed comprehension of carefully matched classes of words, manipulating grammatical subcategory (noun and verb) and semantic (concrete and abstract) characteristics for participants with semantic dementia (SD) or probable Alzheimer's disease (AD). Participants selected the best of four words that matched a verbal description. Participants with AD or SD were significantly impaired with verbs compared with nouns. Moreover, participants with SD showed significantly greater difficulty with motion verbs compared to cognition verbs. The authors argue that two factors contribute to the difficulty with motion verbs for patients with SD. First, the verb semantic network is very poorly organized relative to the noun semantic network, leaving verbs more vulnerable to a progressive neurodegenerative disease. Second, visual feature knowledge is degraded in patients with SD because of the anatomic distribution of the disease in visual association cortex, causing relatively greater difficulty for concrete verbs compared to abstract verbs.

Aged↗

PubMed2004

Alcohol's dissociation of implicit and explicit memory processes: implications of a parallel distributed processing model of semantic priming.

Alcohol's dissociation of implicit (unintentional) and explicit (intentional) memory processes in social drinkers was examined. It was hypothesized that an alcohol challenge would lower the percentage of words recalled and result in more retroactive interference in explicit recall tasks but would not lengthen reaction time in an implicit semantic priming task involving highly semantically similar words. Men and women completed all memory tasks in each of 2 counterbalanced sessions (alcohol challenge vs. no-alcohol) separated by 1 week. Alcohol significantly degraded processing in both explicit memory tasks, yet implicit semantic priming remained intact. A parallel distributed processing model that simulates semantic memory is presented. When this system is strongly activated, it does not appear to be altered during moderate alcohol intoxication.

Adult↗

PubMed2004

Semantic priming of different affective categories.

The authors investigated affective semantic priming using a lexical decision task with 4 affective categories of related word pairs: neutral, happy, fearful, and sad. Results demonstrated a striking and reliable effect of affective category on semantic priming. Neutral and happy prime-targets yielded significant semantic priming. Fearful pairs showed no or modest priming facilitation, and sad primes slowed reactions to sad targets. A further experiment established that affective primes do not have generalized facilitatory-inhibitory effects. The results are interpreted as showing that the associative mechanisms that support semantic priming for neutral words are also shared by happy valence words but not for negative valence words. This may reflect increased vigilance necessary in adverse contexts or suggest that the associative mechanisms that bind negative valence words are distinct.

Adult↗

PubMed2006

Dissociative effects of stimulus quality on semantic and morphological contexts in visual word recognition.

Semantic and morphological contexts were manipulated jointly with stimulus quality under conditions where there were few related prime-target pairs (i.e., low relatedness proportion) in a lexical decision experiment. Additive effects of semantic context and stimulus quality on RT were observed, replicating previous work. In contrast, morphological context interacted with stimulus quality. This dissociation is discussed in the context of Besner and colleagues' evolving multistage framework. The essence of the account is that 1) stimulus quality affects feature and letter levels, but not later levels, 2) feedback from semantics to the lexical level is inoperative under low relatedness proportion conditions (hence stimulus quality and semantic context yield additive effects), whereas 3) feedback from the lexical level to the letter level is intact, hence stimulus quality and morphological context produce an interaction by virtue of them affecting a common stage of processing.

Attention↗

PubMed2001

Basic processes in reading: semantics affects speeded naming of high-frequency words in an alphabetic script.

Previous work on single-word naming in university-level readers has shown that semantic factors affect the naming of low frequency words both in an alphabetic script like English, which is often irregular in terms of the spelling-sound correspondences, and in the syllabic Japanese Kana script, in which the spelling-sound correspondences are consistent. The present experiment shows that a semantic factor (imageability) affects naming time to both low- and high-frequency words in an alphabetic script (Persian) when the word is opaque (vowels not specified) but not when it is transparent (vowels specified). Other characteristics of opaque words that promote the use of semantics are discussed. At least in some orthographies, semantics play a larger role in single-word naming than previously thought.

Adult↗

PubMed2005

Semantic deficits in children with language impairments: issues for clinical assessment.

Children with language impairments demonstrate a broad range of semantic difficulties, including problems with new word acquisition, storage and organization of known words, and lexical access/ retrieval. Unfortunately, assessments of children's semantic skills are often limited to measures of receptive and expressive vocabulary size. As a result, the semantic deficits of these children may not receive the attention they need. This article explores the word-learning, lexical storage, and lexical access skills of children with language impairments and the theories that account for their performance. Our review culminates with specific recommendations for speech-language pathologists to improve the breadth of their semantic assessments.

Child↗