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PubMed1991

Semantic processing of unattended parafoveal words.

The influence that a context word presented either foveally or parafoveally, may exert on the processing of a subsequent target word was studied in a semantic decision task. Fourteen subjects participated in the experiment. They were presented with word-nonword pairs (prime). One member of the pair (which the subjects had to attend to) appeared centrally, the other parafoveally. The prime was followed by a target at two inter-stimulus intervals (ISI; 200 and 2000 msec). The word stimulus of the pair could be semantically related or unrelated to the target. The subjects' task was to classify the target as animal or not animal by pressing one of two buttons as quickly as possible. When the target word was semantically associated with the foveal (attended) word the reaction times were faster for both ISIs; when it was associated with the parafoveal (unattended) word in the prime pair, there were facilitatory effects only in the short ISI condition. A second experiment was run in order to evaluate the possibility that the obtained results were due to identification of the parafoveal stimulus. The same prime-target pairs of experiment 1 (without the target stimuli) were used. The prime-target pairs were presented to fourteen subjects who were requested to name the foveal (attended) stimulus and subsequently, if possible, the parafoveal (unattended) one. Even in this condition, percentage of identification of the unattended word was only 15%, suggesting that previous findings were not due to identification of unattended stimuli. Results are discussed in relation to Posner and Snyder's (1975) dual coding theory.

Adult↗

PubMed1991

N400 and semantic categorization in schizophrenia.

The N400 component of event-related potentials (ERPs) was investigated in medicated schizophrenic patients and normal controls in a semantic categorization task. The subjects' task was to indicate whether pairs of words were semantically related or unrelated. The ERPs to the unrelated second words of the pairs contained a negative component, N400, which was reduced and delayed in the patients. However, inspection of individual subjects' data indicated that N400 was abnormal only in a subgroup of schizophrenics. Abnormalities in the amplitude of N400 suggest impairments in semantic expectancies, whereas abnormalities in the latency of N400 suggest a delay in information processing.

Adult↗

PubMed1989

The locus of the effects of sentential-semantic context in spoken-word processing.

Models of word recognition differ with respect to where the effects of sentential-semantic context are to be located. Using a crossmodal priming technique, this research investigated the availability of lexical entries as a function of stimulus information and contextual constraint. To investigate the exact locus of the effects of sentential contexts, probes that were associatively related to contextually appropriate and inappropriate words were presented at various positions before and concurrent with the spoken word. The results show that sentential contexts do not preselect a set of contextually appropriate words before any sensory information about the spoken word is available. Moreover, during lexical access, defined here as the initial contact with lexical entries and their semantic and syntactic properties, both contextually appropriate and inappropriate words are activated. Contextual effects are located after lexical access, at a point in time during word processing where the sensory input by itself is still insufficiently informative to disambiguate between the activated entries. This suggests that sentential-semantic contexts have their effects during the process of selecting one of the activated candidates for recognition.

Attention↗

PubMed1982

Decoding paralinguistic signals: effect of semantic and prosodic cues on aphasics' comprehension.

A matching task between sentences voiced with joyful, angry, or sad intonation and pictures of facial expressions representing the same emotions is proposed to 27 aphasics and 20 normal subjects. Semantic contents are either meaningless, neutral, or affectively loaded. In the affective-meaning condition, content is redundant with prosody or conflicting with it. Results are 1. a greater number of nonprosodic choices in the aphasic group; 2. an identical influence of the congruence/conflict variable on aphasic and control subjects; 3. an identical influence of the semantic content of the conflict sentences on both groups. Aphasic impairment is interpreted as purely quantitative, since affective semantic content influences the decoding of the sentences.

Adult↗

PubMedDate not supplied

Another look at semantic relational categories and language impairment.

Earlier comparative studies of language-impaired and normal children involved semantic-relational analyses of broad categories (e.g., action, locative action, and so on) in which utterance types were not differentiated. In this study, locative action utterances were differentiated by the types of locative words used singly and in combination. The types of utterances used by a language-impaired child were tracked between 1 year 6 months and 3 years and compared with those of three age- and MLU-matched normal children. The results suggested that differences in the semantic properties of language-impaired and normal children's utterances may go undetected unless a fine-grained analysis is performed on the types of expressions used within a global relational category. The potential value of extending semantic-relational analyses by exploring word use in syntactic contexts is addressed.

Child Development↗

PubMed1983

Semantic processing can facilitate free recall in mildly retarded adolescents.

The efficacy of semantic processing in free recall was investigated in two experiments with EMR adolescents. In Experiment 1, they were taught to use one of two semantic strategies for memorizing a 15-word list. Compared with controls, neither strategy helped recall either in original learning or transfer. In Experiment 2, one of the semantic strategies, a story mnemonic, was investigated further. Rather than being taught to construct their own stories as in Experiment 1, subjects in Experiment 2 were provided with experimenter-composed stories. They showed better immediate recall and retention after 2 months than did no-strategy controls. However, about 1 year after original learning, the retention of experimental and control subjects no longer differed. Discussion focused on the story mnemonic's potential utility and the criteria for judging such potential, e.g., amount of facilitation, ease of training and performance of the strategy, and the degree of its generalizability.

Adolescent↗

PubMed1984

Hemispheric asymmetry in use of semantic category information.

When two pictures of common objects were presented sequentially, the second was named more quickly if both were members of the same semantic category. This semantic priming effect occurred only when both pictures went directly to the left hemisphere. If the target or prime stimulus was presented to the left visual field--right hemisphere, no priming effect was observed. These results suggest that semantic category information is activated and used by the left hemisphere of the brain.

Adult↗

PubMed1987

Episodic, semantic and procedural memory in a case of amnesia at an early age.

The patient C.C. developed an amnesic syndrome at the age of 10 yr. Like adult amnesics, C.C. demonstrated impaired episodic memory for both verbal and visual materials although immediate memory span was spared. However, striking deficits were also observed on a wide variety of semantic memory tasks, including reading vocabulary and verbal fluency tests, semantic classification and lexical decision tasks and tests of verbal intelligence. On the other hand, C.C. showed normal learning and retention of two procedural tasks. It was argued that this evidence is inconsistent with the view that the amnesic syndrome represents a selective defect of episodic memory that leaves semantic memory relatively unaffected.

Amnesia↗

PubMed1987

Verbal memory and semantic clustering in right brain-damaged patients.

Twenty-four right brain-damaged patients without ostensive signs of intellectual impairment or disturbances of verbal comprehension, and 20 normal control subjects were given two lists of words, one (the Rey's Auditory) in which 15 words were semantically unrelated and a second in which 15 two-syllable words belonged to one of three categories. The results demonstrated no difference between the two subject groups, either in the immediate or the delayed recall sections of the Rey's test. The immediate recall section of the semantic verbal memory task, on the contrary, showed significantly poor performance by the right brain-damaged patients. These results suggest an impairment of semantic clustering processes after right hemisphere damage.

Aged↗

PubMed1990

Semantic and phonemic priming in the cerebral hemispheres.

Representation of semantic and phonemic codes in the cerebral hemispheres was investigated in two priming experiments where prime and target words were independently projected to the left or right visual fields. The first experiment, using phonemic primes, confirmed the view that phonological information is not accessible to the right hemisphere. Priming effects were obtained only when the prime and target were both projected to the right visual field. The second experiment, employing category exemplars as primes, again found the left hemisphere to be the principal locus of the priming effects. The right hemisphere was unable, by itself, to activate words related to the exemplar prime. However, projection of the prime to the right visual field significantly facilitated responses to left visual field targets. The present findings support the view advanced by Drews (Neuropsychologia 25, 419-427, 1987) and Levy and Trevarthen (J. exp. Psychol., Hum. Percep. Perform. 2,299-312, 1976) that the left lexicon is structured in accordance with an hierarchy of logical semantic relationships, while the right lexicon is organized on the basis of simple associations between concepts. It is suggested, furthermore, that the patterns of semantic, but not phonological, activation invoked by a prime may be relayed between the two lexicons.

Adult↗

PubMed1991

An investigation of naming errors following semantic and phonemic cueing.

This study investigated the types of verbal errors produced by aphasic patients following phonemic and semantic cueing. Twenty-eight aphasic patients--10 Broca's, 10 Wernicke's and 8 conduction aphasics--served as subjects. Semantic and phonemic cues were administered on object and action confrontation-naming tasks. When subjects did not respond correctly to phonemic cueing, a significantly greater number of phonemic errors were produced, with a concurrent decline in related words and extended circumlocutions. When subjects failed to respond to semantic cueing on the action task, there was an increase in a number of error categories.

Anomia↗

PubMed1993

A left visual field bias for semantic encoding of unattended words.

Previous studies have shown that verbal processing in both normal individuals and a split-brain patient can be strongly affected by the semantic category of an unattended word presented to the left visual field (LVF). The effect was interpreted in terms of inhibition, since responses were slower when the unattended LVF word belonged to the same category as the target word. The present experiment discriminated between two alternative explanations for this finding. Subjects were presented with two letter strings, one in central vision and one to the left or right of centre. Subjects made a speeded lexical decision to the central string, and were instructed to ignore the lateral string. When a word was presented to the LVF subjects responded more slowly when it was semantically related to the central word. When an unattended word was presented to the RVF, its semantic relationship to the central word had no effect on decision latency. This finding is discussed in relation to views of performance laterality and selective attention.

Analysis of Variance↗

PubMed1995

Lateralized free-association priming: implications for the hemispheric organization of semantic memory.

The organization of semantic memory in intact cerebral hemispheres was examined by a free-association priming task. Normal subjects studied a list of word pairs where the semantic relations were either coordinate (e.g. saw-axe) or locative (e.g. bear-forest). Priming of the word pairs was tested by presenting test cues (initial words of the pairs) to the left or to the right visual field. Results showed an interaction between visual field and word pair type, suggesting a qualitative difference in the semantic organization of the hemispheres. Specifically, the results support the view that coordinate relations are represented in both hemispheres whereas locative relations are represented mainly in the right hemisphere.

Brain↗

PubMed1996

Semantic-free scaling of odor quality.

The validity of the odor quality reports given by naive human subjects is often questionable. On the one hand, social conventions can influence the labeling of odorants, especially those that have putrid or uncommon odor qualities, and on the other, semantic differences exist for odor descriptors among individuals. We are interested in the individual differences in the quality reports elicited by two nominally putrid odorants, androstenone (AND) and pemenone (PEM). Here we sought to establish empirical support for the individual differences previously obtained in studies of their odor quality, using a nonverbal, semantic-free method of classification. Undergraduate volunteers sniffed a moderate concentration (390 microM) of PEM, rated its intensity, and provided a verbal odor descriptor. The subjects were then classified as PEM osmic (n = 42) if the quality report was putrid (rancid, urinous, sweaty), allosmic (n = 23), if the quality was nonputrid, and anosmic (n = 39) if no odor was detected. The subjects then sorted 15 odorants matched for intensity, five selected from each of three nominal odor quality types, into as many odor groups as they wished, as long as each group contained all of the compounds with similar odors. The number of times each odorant was paired with another was used as data for an independent multidimensional scaling with ALSCAL, for each class of subject. Three-dimensional solutions showed that this nonverbal, semantic-free scaling method produced odor classifications consistent with those found when each class of subject reported odor qualities from a defined list of quality descriptors. Cluster analysis of the MDS coordinates revealed that these solutions also retained the individual odor quality differences thought to be characteristic of osmic, allosmic and anosmic subjects.

Adult↗

PubMed1985

Semantic priming effects for stimuli presented to the right and left visual fields.

Studies that have addressed the possibility of hemispheric differences in semantic priming effects have yielded contradictory results. This paper reports the findings of two experiments intended to shed greater light on the issue of hemispheric differences in semantic priming. Experiment 1 used a hemiretinal paradigm and examined manual response latency and response accuracy to four types of word pairs; categorically related, syntactically related, unrelated, and pairs containing a nonword member. Experiment 2 examined the effects of unrecognized, disambiguating flank words on verbal responses to a centrally presented homograph. Experiment 1 yielded no significant visual field differences in magnitude of priming effects when response latency served as the dependent measure, although categorical relatedness facilitated response accuracy for left but not right visual field stimuli. In experiment 2, the disambiguating words had a significant effect on meaning interpretation of the homographs that was independent of visual field of presentation. Taken together, the results of these studies are interpreted as indicating that semantic aspects of linguistic input are automatically processed and can influence the content and latency of subsequent responses, whether presented to the left or right visual field.

Adolescent↗

PubMed1989

The effect of semantic and syntactic structure on verbal memory in Alzheimer's disease.

This study examined the ability of 17 patients with Alzheimer's disease and 17 normal-old subjects to recall short sentences that were normal, or had a disruption in either their semantic structure, their syntactic structure, or both their semantic and syntactic structure. Results showed that sentence recall performance was affected similarly in the demented and normal-old subjects by both the syntactic and semantic structure of the sentences. The presence of either type of language structure appeared to allow both normal and demented subjects to organize strings of words into multiword chunks for more efficient memory encoding.

Aged↗

PubMed1990

Semantic errors in a deep dyslexic.

A case of a Swedish-speaking deep dyslexic is reported whose semantic paralexias appeared to result mainly from a lexical retrieval failure in oral reading. He was able to draw correct pictures of the written words for which he had simultaneously produced a semantically erroneous oral reading response. Repeated attempts to correct paralexic responses were common, indicating that the patient was often aware of the errors. His lexical retrieval problems and semantic errors extended to naming as well, and the results support Nolan and Caramazza's (1982, Brain and Language, 16, 237-264), dual-deficit model of deep dyslexia.

Adult↗

PubMed1983

Semantic encoding deficits in a case of traumatic amnesia.

A 33-year-old patient was studied neuropsychologically 19 years after sustaining severe head trauma. A recent CT scan showed lesions in the left frontal and right temporal regions. Performance on standard memory tests, both verbal and visuospatial, was extremely poor, although other intellectual functioning was relatively spared. The patient showed some interesting deficits in semantic processing. In a depth of processing task there was no advantage for words where semantic encoding had been induced. Neither was there any release from proactive interference after shifts in semantic categories. Deficits were also observed in short-term memory distractor tasks as well as in cueing tasks. These findings suggest that the cognitive deficits commonly observed in Korsakoff's disease can also be present in other amnesic disorders and may in part be related to cortical and especially frontal lobe atrophy.

Adult↗