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PubMed2005

Semantic relevance best predicts normal and abnormal name retrieval.

The relevance of a semantic feature measures its contribution to the "core" meaning of a concept. In a naming-to-description task, we investigated the predictive power of relevance in comparison with frequency, familiarity, typicality, and Age-of-Acquisition. In a group of Alzheimer patients with semantic disorder, relevance turned out to be the best predictor of name retrieval accuracy in a naming-to-description task. The same pattern of results was observed in normal controls. Relations between semantic relevance and the parameters of the concepts are discussed in order to highlight the mechanism of concept activation in a naming-to-description task.

Age Factors↗

PubMed2005

Cross-modal visuo-tactile matching in a patient with a semantic disorder.

This study is concerned with the nature of object representations coded within and between vision and touch, assessed through a study of perceptual matching abilities in a patient with impaired semantic knowledge for objects: JP. Prior work with JP has indicated that she has a category-specific deficit that is particularly severe for tools (see the Case report and Humphreys, G. W., Vernier, M. -P., & Riddoch, M. J. A semantic deficit for tools, in preparation). Here, we test whether, despite this semantic deficit, JP can perform object matching under various conditions. We demonstrate that JP could perform matching across sensory modalities (between touch and vision) when objects appeared in the same view, but this did not generalise across views. In addition, JP was able to match from 3D felt representations to 2D visual representations provided the stimuli were real (previously familiar) objects. The data support the idea that matching between touch and vision can be based on common view-specific, perceptual representations, sensitive to the familiarity of individual objects.

Aged↗

PubMed2005

Qualitative features of semantic fluency performance in mesial and lateral frontal patients.

Semantic verbal fluency is widely used in clinical and experimental studies. This task is highly sensitive to the presence of brain pathology and is frequently impaired after frontal lesions. Besides the total number of words generated, a qualitative analysis of their sequence can add valuable information about the impaired cognitive components. Thirty-four frontal patients and a group of matched controls were examined. Besides the number of words and subcategories retrieved by each group, we analysed two distinct aspects of the word sequence: the search strategy through a semantically organised store and the ability to switch from one subcategory to another. We checked whether the pattern of impairment changed according to the lesion site within the frontal lobe. Overall, patients produced fewer words than controls. However, only lateral frontal patients presented a reduced semantic relatedness between contiguously produced words and a specifically increased proportion of switches to different subcategories. The performance of lateral frontal patients was in line with the hypothesis of a search strategy impairment and cannot be attributed to a switching deficit. The performance of mesial frontal patients could be ascribed to a general deficit of activation.

Adult↗

PubMed2005

Working memory and semantic involvement in sentence processing: a case of pure progressive amnesia.

ED, a 83-year-old woman, meets the criteria of pure progressive amnesia, with gradual impairment of episodic and autobiographical memory, sparing of semantic processing and strong working memory (WM) deficit. The dissociation between disturbed WM and spared semantic processing permitted testing the role of WM in processing anaphors like pronouns or repeated names. Results showed a globally normal anaphoric behavior in two experiments requiring anaphoric processing in sentence production and comprehension. We suggest that preserved semantic processing in ED would have compensated for working memory deficit in anaphoric processing.

Aged, 80 and over↗

PubMed2004

Temporal lobe abnormalities in semantic processing by criminal psychopaths as revealed by functional magnetic resonance imaging.

We tested the hypothesis that psychopathy is associated with abnormalities in semantic processing of linguistic information. Functional magnetic resonance imaging (fMRI) was used to elucidate and characterize the neural architecture underlying lexico-semantic processes in criminal psychopathic individuals and in a group of matched control participants. Participants performed a lexical decision task in which blocks of linguistic stimuli alternated with a resting baseline condition. In each lexical decision block, the stimuli were either concrete words and pseudowords or abstract words and pseudowords. Consistent with our hypothesis, psychopathic individuals, relative to controls, showed poorer behavioral performance for processing abstract words. Analysis of the fMRI data for both groups indicated that processing of word stimuli, compared with the resting baseline condition, was associated with neural activation in bilateral fusiform gyrus, anterior cingulate, left middle temporal gyrus, right posterior superior temporal gyrus, and left and right inferior frontal gyrus. Analyses confirmed our prediction that psychopathic individuals would fail to show the appropriate neural differentiation between abstract and concrete stimuli in the right anterior temporal gyrus and surrounding cortex. The results are consistent with other studies of semantic processing in psychopathy and support the theory that psychopathy is associated with right hemisphere abnormalities for processing conceptually abstract material.

Adult↗

PubMed2004

An electrophysiological (ERP) component, the recognition potential, in the assessment of brain semantic networks in patients with schizophrenia.

Abnormal activation of semantic networks may be the underlying basis for thought disorder (ThD) in patients with schizophrenia. However, whether this abnormality consists of increased or decreased activation is unclear. Previous behavioral and electrophysiological (N400) data have failed to yield consistent evidence for clarifying this hypothesis. One of the event-related potentials (ERP) components (the recognition potential, RP), presumably reflecting activation of specific semantic networks involved in ThD, has not been used to studies of schizophrenia, and may add additional information to support or refute this hypothesis. In an initial experiment, RP amplitude was reduced in schizophrenic patients, but particularly in those with ThD. In a second experiment, in addition to reduced overall RP amplitude, concrete words were shown to have higher amplitudes than abstract words in both patients and controls, supporting a relative integrity of the lexicon in ThD patients. RP reduction suggests that a fewer number of networks' elements are activated when an incoming word is processed, thus supporting hypoactivation of the semantic networks as the basis for ThD.

Adult↗

PubMed2000

The influence of semantic context on initial eye landing sites in words.

To determine the role of ongoing processing on eye guidance in reading, two studies examined the effects of semantic context on the eyes' initial landing position in words of different levels of processing difficulty. Results from both studies clearly indicate a shift of the initial fixation location towards the end of the words for words that can be predicted from a prior semantic context. However, shifts occur only in high-frequency words and with prior fixations close to the beginning of the target word. These results suggest that ongoing perceptual and linguistic processes can affect the decision of where to send the eyes next in reading. They are explained in terms of the easiness of processing associated with the target words when located in parafoveal vision. It is concluded that two critical factors might help observing effects of linguistic variables on initial landing sites, namely, the frequency of the target word and the position where the eyes are launched from as regards to the beginning of the target word. Results also provide evidence for an early locus of semantic context effects in reading.

Adult↗

PubMed2000

Age-of-acquisition effects in semantic processing tasks.

In two experiments, we examined whether word age-of-acquisition (AoA) is a reliable predictor of processing times in semantic tasks. In the first task, participants were asked to say the first associate that came to mind when they saw a stimulus word; the second task involved a semantic categorisation between words with a definable meaning and first names. In both tasks, there were significantly faster responses to earlier-acquired than to later-acquired words. On the basis of these results, we argue that age-of-acquisition effects do not originate solely from the speech output system, but from the semantic system as well.

Adult↗

PubMed2001

Effects of semantic context in the naming of pictures and words.

Two experiments investigated whether lexical retrieval for speaking can be characterized as a competitive process by assessing the effects of semantic context on picture and word naming in German. In Experiment 1 we demonstrated that pictures are named slower in the context of same-category items than in the context of items from various semantic categories, replicating findings by Kroll and Stewart (Journal of Memory and Language, 33 (1994) 149). In Experiment 2 we used words instead of pictures. Participants either named the words in the context of same- or different-category items, or produced the words together with their corresponding determiner. While in the former condition words were named faster in the context of same-category items than of different-category items, the opposite pattern was obtained for the latter condition. These findings confirm the claim that the interfering effect of semantic context reflects competition in the retrieval of lexical entries in speaking.

Analysis of Variance↗

PubMed2003

Processing correlates of lexical semantic complexity.

This paper explores how verb meanings that differ in semantic complexity are processed and represented. In particular, we compare eventive verbs, which denote causally structured events, with stative verbs, which denote facts without causal structure. We predicted that the conceptually more complex eventive verbs should take longer to process than stative verbs. Two experiments, a lexical decision task and a self-paced reading study, confirmed this prediction. The findings suggest that (a) semantic complexity is reflected in processing time, (b) processing verb meanings involves activating properties of the event structure beyond participants' roles, and (c) more generally, lexical event structures, which subsume thematic roles, may mediate between syntactic knowledge and semantic interpretation.

Humans↗

PubMed1997

Associative and semantic priming effects occur at very short stimulus-onset asynchronies in lexical decision and naming.

Prior research has found significant associative/semantic priming effects at very short stimulus-onset asynchronies (SOAs) in experimental tasks such as lexical decision, but not in naming tasks (however, see Lukatela and Turvey, 1994). In this paper, the time course of associative priming effects was analyzed a several very short SOAs (33, 50, and 67 ms), using the masked priming paradigm (Forster and Davis, 1984), both in lexical decision (Experiment 1) and naming (Experiment 2). The results show small--but significant--associative priming effects in both tasks. Additionally, using the masked priming procedure at the 67 ms SOA. Experiments 3 and 4, shows facilitatory priming effects for both associatively and semantically (unassociated) related pairs in lexical decision and naming tasks. That is, automatic priming can be semantic. Taken together our data appear to support interactive models of word recognition in which semantic activation may influence the early stages of word processing.

Adult↗

PubMed2002

Anomia for common names and geographical names with preserved retrieval of names of people: a semantic memory disorder.

This paper describes the case of an anomic patient (FH) who is impaired at naming pictures of objects but has no difficulties in recalling the names of familiar people. Even though his performance on McKenna's (1997) Category Specific Naming Test was at the first percentile, he consistently recalled the names of familiar people as successfully as controls. It is argued that the pattern of performance displayed by FH represents a much clearer double dissociation with proper name anomia than any case previously reported (Cipolotti et al., 1993; Semenza and Sgaramella, 1993). FH is unable to provide detailed semantic information about many of the objects that he cannot name, even though he can recall semantic information about familiar people. Consequently his case appears to represent the mirror image of the proper name anomic patient (APA) described by Miceli et al. (2000) who was unable to recall detailed semantic information about many of the people she was unable to name. Further investigation of FH's anomia revealed impairments in retrieving both common nouns and verbs, and difficulties in retrieving and comprehending geographical names. It is argued that FH's preserved ability to name and recall biographical information about people supports the view that knowledge about familiar people may be subserved by its own dedicated neural subsystem (Kay and Hanley, 1999; Miceli et al., 2000; Gentileschi et al., 2001).

Aged↗

PubMed1997

Dissociation between semantic and autobiographic memory: a case report.

We report a patient who showed a dissociation between impaired semantic memory and preserved autobiographic memory. M.N., a 56-year-old right-handed woman, developed a supra sellar meningioma and underwent multiple operations. Following Lineac radiation, necrosis occurred in the left temporal lobe. Magnetic Resonance Imaging revealed bilateral lesions in the temporal lobes and in the right basal frontal lobe. The patient's intellectual deterioration and anterograde amnesia were mild. Language was preserved, but for a subtle anomia. Autobiographic memory remained intact, while semantic memory for public events, historical figures, cultural items, knowledge of low frequency words and technical terms related to her profession was severely impaired. We hypothesize that bilateral lesions of the anterior half of the middle region of the temporal lobe plays a crucial role in causing deficits in semantic memory.

Amnesia↗

PubMed2005

Love is... an abstract word: the influence of lexical semantics on verbal short-term memory in Williams syndrome.

It has been claimed that verbal short-term memory in Williams syndrome is characterised by an over-use of phonological coding alongside a reduced contribution of lexical semantics. We critically examine this hypothesis and present results from a memory span task comparing performance on concrete and abstract words, together with a replication of a span task using phonologically similar and phonologically dissimilar words. Fourteen participants with Williams syndrome were individually matched to two groups of typically developing children. The first control group was matched on digit span and the second on vocabulary level. Significant effects were found for both the semantic and the phonological variables in the WS group as well as in the control groups, with no interaction between experimental variable and group in either experiment. The results demonstrate that, despite claims to the contrary, children and adults with WS are able to access and make use of lexical semantics in a verbal short-term memory task in a manner comparable to typically developing individuals.

Adolescent↗

PubMed1979

Semantic judgment ability in adult aphasia.

Recent psycholinguistic literature suggests that language usage often involves the ability to make judgments or appraisals about various aspects of language. It was therefore the purpose of the present study to examine the semantic judgment or evaluation abilities of thirty persons with aphasia in comparison to these same behaviors in a group of thirty normal individuals. That is, this study examined subject ability to use knowledge to make comparisons or judgments in reference to specific criteria. Results support the existence of a judgment capacity and indicate that persons with aphasia are impaired in their ability to evaluate semantic material. Therefore, speech pathologists may wish to include semantic judgment tasks in their evaluation procedures and plan therapy directed toward the retrieval of judgment responses.

Aged↗

PubMed1981

Word-retrieval in aphasia: an investigation of semantic complexity.

Performance of aphasic subjects in adjective recognition and production tasks in which adjectives varied in semantic feature and markedness complexity was investigated. Twelve pairs of adjectives were examined in three experimental tasks; viz., picture recognition, antonym production, and sentence completion. Subjects were eight nonfluent and eight fluent aphasics. The results indicate significant differences in performance were dependent upon semantic features, markedness, experimental tasks, and type of aphasia. The discussion related semantic complexity to cognitive processes.

Aphasia↗

PubMed1985

A case of visual agnosia showing a disorder of pre-semantic visual classification.

A case (J.R.) of associative visual agnosia (loss of meaning for visually presented objects without any serious sensory disorder) is reported. When asked to match a given name to sample the patient made both visual and semantic errors. Whereas semantic errors were reduced by priming, visual errors were intractable. It is argued that there is a disorder at the stage of pre-semantic abstraction, similar to that postulated elsewhere for some cases of deep dyslexia, contributing to the agnosia.

Adult↗

PubMed1987

The disconnection in anomic aphasia between semantic and phonological lexicons.

PB, a right handed woman aged 26, has developed anomic language disturbances following right frontal and left temporal brain damage due to a road traffic accident. Her anomia shows exceptional features: it occurs in naming tasks in test conditions but not in continuous speech; it involves comprehension deficits but very few semantic errors in expression; it improves with phonemic, but not with semantic cues. These features, it is argued, indicate the disconnection between two intact lexicons: the semantic and the phonological.

Adult↗