Brain responses related to semantic meaning

Evoked Potentials from electroencephalogram (EEG) recording were averaged to many visually presented word stimuli whose semantic meanings were specified along Osgood's semantic dimensions of Evaluation, Potency, and Activity [Miron &; Osgood, 1966, in R. B. Cattell (Ed.), Handbook of multivariate experimental psychology, Chicago: Rand-McNally; Osgood, 1971, Journal of Social Issues, 27, 5–63; Osgood, May, &; Miron, 1975, Cross-cultural universals of affective meaning, Urbana, Ill.: University of Illinois Press]. Multivariate analyses classified the Evoked Potentials to six semantic classes with success rates more than twice chance expectation. The pattern of brain activity related to the six semantic classes was similar for (i) two sets of words, (ii) 10 subjects used to develop the analyses, and (iii) an added, new subject.     

Convergent cortical representation of semantic processing in bilinguals

This study examined whether semantic processes in two languages (English and Spanish) are mediated by a common neural system in fluent bilinguals who acquired their second language years after acquiring their first language. Functional magnetic resonance imaging was performed while bilingual participants made semantic and nonsemantic decisions about words in Spanish and English. There was greater activation for semantic relative to nonsemantic decisions in left and right frontal regions, with greater left frontal activation. The locations of activations were similar for both languages, and no differences were found when semantic decisions for English and Spanish words were compared directly. These results demonstrate a shared frontal lobe system for semantic analysis of the languages and are consistent with cognitive research on bilingualism indicating that the two languages of a bilingual person access a common semantic system.     

Electrophysiological responses to evaluative priming: the LPP is sensitive to incongruity

Previous studies examining event-related potentials and evaluative priming have been mixed; some find evidence that evaluative priming influences the N400, whereas others find evidence that it affects the late positive potential (LPP). Three experiments were conducted using either affective pictures (Experiments 1 and 2) or words (Experiment 3) in a sequential evaluative priming paradigm. In line with previous behavioral findings, participants responded slower to targets that were evaluatively incongruent with the preceding prime (e.g., negative preceded by positive) compared to evaluatively congruent targets (e.g., negative preceded by negative). In all three studies, the LPP was larger to evaluatively incongruent targets compared to evaluatively congruent ones, and there was no evidence that evaluative incongruity influenced the N400 component. Thus, the present results provide additional support for the notion that evaluative priming influences the LPP and not the N400. We discuss possible reasons for the inconsistent findings in prior research and the theoretical implications of the findings for both evaluative and semantic priming.     

Cognitive integration of language and memory in bilinguals: semantic representation

Understanding cognitive research on the integration of 2 languages in bilingual memory is difficult because of the different terminology, methodology, analysis, and interpretation strategies that scholars with different backgrounds bring to the research. These studies can be usefully categorized on 2 dimensions: memory for verbal experience versus linguistic knowledge, and systemwise versus pairwise issues. Experimental findings in this area converge on the conclusion that at the word meaning/conceptual level, both episodic and linguistic memory can be characterized as shared at the systems level and at least partly shared at the pairwise translation-equivalent level. Interpretation problems that stem from weak hypothesis testing structure and from covert translation can be minimized by using appropriate design and analysis techniques.     

Differentiating the N3 and N4 electrophysiological semantic incongruity effects

An event-related potential termed the N4 has been widely studied due to its sensitivity to semantic incongruity. A recent report (Nobre & McCarthy, 1994) indicates there is also an N3 component that is sensitive to semantic incongruity. To differentiate these two components, an existing data set with 65 electrode sites, 78 subjects, and 120 sentences was examined. Instead of the usual procedure of averaging over the stimuli within distinct categories for each subject, a new approach--averaging over subjects--was employed. In this item average approach, 120 averages (one per sentence) were produced. Correlational analyses indicate that the N3 is equally sensitive to cloze probability and sentential constraint. The N4, by contrast, is more sensitive to sentential constraint and less to cloze probability; it is also correlated with familiarity. We interpret these results as evidence that the N3 is more responsive to semantic fit whereas the N4 is more responsive to semantic expectancy.     

A study of semantic and syntactic processing in monolinguals and fluent early bilinguals

The present study consists of two reaction-time experiments administered in English. These experiments were designed to compare semantic and syntactic processing in English monolinguals and fluent early French-English bilinguals. Results of both experiments revealed that the bilinguals did not function as the English monolinguals did. That is, their reaction times were slower and they made twice as many errors in response to certain sentences. These findings are especially important for two reasons: (1) The bilinguals were all highly fluent, and in most cases dominant, in English, and (2) the bilinguals exhibited systematic differences in two different linguistic components (the semantic and the syntactic). The results are viewed as evidence of the interdependence of the bilinguals' languages. Some note is made of individual patterns of response, and two interpretations of linguistic interdependence are provided.     

Brain responses to filled gaps

An unresolved issue in the study of sentence comprehension is whether the process of gap-filling is mediated by the construction of empty categories (traces), or whether the parser relates fillers directly to the associated verb's argument structure. We conducted an event-related potentials (ERP) study that used the violation paradigm to examine the time course and spatial distribution of brain responses to ungrammatically filled gaps. The results indicate that the earliest brain response to the violation is an early left anterior negativity (eLAN). This ERP indexes an early phase of pure syntactic structure building, temporally preceding ERPs that reflect semantic integration and argument structure satisfaction. The finding is interpreted as evidence that gap-filling is mediated by structurally predicted empty categories, rather than directly by argument structure operations.     

Visual field asymmetries for rhyme and semantic tasks in fluent and nonfluent bilinguals.

A tachistoscopic study investigated hemispheric specialization among fluent and nonfluent bilinguals for rhyme and semantic tasks in both their languages. Fluent bilinguals gave faster responses and made fewer errors in their responses to the words presented in the RVF(LH) while the opposite happened for nonfluent, which indicates greater RH participation in the first stages of a second language. Fluent bilinguals performed better not only in the second but also in their native language, suggesting superior language skills on the part of fluent bilinguals. A LVF(RH) superiority was obtained for semantic tasks, indicating RH participation in semantic judgments. Another finding was a high ratio of first-born children among fluent bilinguals, potentially explained in terms of parental attitudes toward first- versus later born children.     

Effects of the degree of meaning similarity on cross-language semantic priming in highly proficient bilinguals

This study aimed to determine if access to meaning can be directly achieved from the words in the two languages, examining the influence of the degree of semantic overlap between related words across languages in the pattern of priming effects. Nonassociative semantically related words (members of the same category) were used, avoiding explicitly associative relationships. Using a priming paradigm, highly proficient Catalan–Spanish bilinguals were visually presented with pairs of words that either were translations of each other, had a very close semantic relationship (in terms of shared features), a close semantic relationship, or no semantic relationship at all. Participants performed either a lexical decision task (Experiment 1) or a semantic decision task (Experiment 2). The main results of the study were the same in both language directions (Spanish–Catalan and Catalan–Spanish), showing that the degree of semantic overlap (in terms of shared features) between words in different languages can modulate priming effects, regardless of the language of the prime and the task used. These results demonstrate that there is cross-language activation of shared semantic representations and, thus, that highly proficient bilinguals can have direct access to word meaning from the two languages.     

Conceptual representation of verbs in bilinguals: semantic field effects and a second-language performance paradox

It is well known that bilinguals perform better in their first language (L1) than in their second lanaguage (L2) in a wide range of linguistic tasks. In recent studies, however, the authors have found that bilingual participants can demonstrate faster response times to L1 stimuli than to L2 stimuli in one classification task and the reverse in a different classification task. In the current study, they investigated the reasons for this "L2-better-than-L1" effect. English-French bilinguals performed one word relatedness and two categorization tasks with verbs of motion (e.g., run) and psychological verbs (e.g., admire) in both languages. In the word relatedness task, participants judged how closely related pairs of verbs from both categories were. In a speeded semantic categorization task, participants classified the verbs according to their semantic category (psychological or motion). In an arbitrary classification task, participants had to learn how verbs had been assigned to two arbitrary categories. Participants performed better in L1 in the semantic classification task but paradoxically better in L2 in the arbitrary classification task. To account for these effects, the authors used the ratings from the word relatedness task to plot three-dimensional "semantic fields" for the verbs. Cross-language field differences were found to be significantly related to the paradoxical performance and to fluency levels. The results have implications for understanding of how bilinguals represent verbs in the mental lexicon.     

Not just semantics: Strong frequency and weak cognate effects on semantic association in bilinguals

To investigate the possibility that knowledge of two languages influences the nature of semantic representations, bilinguals and monolinguals were compared in a word association task. In Experiment 1, bilinguals produced less typical responses relative to monolinguals when given cues with a very common associate (e.g., given bride, bilinguals said “dress” instead of “groom”). In Experiment 2, bilinguals produced responses as typical as those of monolinguals when given cues with high-frequency associates, but not when given cues with lowfrequency associates. Bilinguals’ responses were also affected, to a certain extent, by the cognate status of the stimulus word pairs: They were more similar to monolinguals’ responses when the cue and its strongest associate were both cognates (e.g., minute-second is minuto-segundo in Spanish), as opposed to both being noncognates. Experiment 3 confirmed the presence of a robust frequency effect on bilingual but not on monolingual association responses. These findings imply a lexical locus for the bilingual effect on association responses and reveal the association task to be not quite as purely semantic as was previously assumed.     

Brain oscillations during semantic evaluation of speech

Changes in oscillatory brain activity have been related to perceptual and cognitive processes such as selective attention and memory matching. Here we examined brain oscillations, measured with electroencephalography (EEG), during a semantic speech processing task that required both lexically mediated memory matching and selective attention. Participants listened to nouns spoken in male and female voices, and detected an animate target (p = 20%) in a train of inanimate standards or vice versa. For a control task, subjects listened to the same words and detected a target male voice in standards of a female voice or vice versa. The standard trials of the semantic task showed enhanced upper beta (25–30 Hz) and gamma band (GBA, 30–60 Hz) activity compared to the voice task. Upper beta and GBA enhancement was accompanied by a suppression of alpha (8–12 Hz) and lower to mid beta (13–20 Hz) activity mainly localized to posterior electrodes. Enhancement of phase-locked theta activity peaking near 275 ms also occurred over the midline electrodes. Theta, upper beta, and gamma band enhancement may reflect lexically mediated template matching in auditory memory, whereas the alpha and beta suppression likely indicate increased attentional processes and memory demands.     

EEG theta and gamma responses to semantic violations in online sentence processing

We explore the nature of the oscillatory dynamics in the EEG of subjects reading sentences that contain a semantic violation. More specifically, we examine whether increases in theta ( approximately 3-7 Hz) and gamma (around 40 Hz) band power occur in response to sentences that were either semantically correct or contained a semantically incongruent word (semantic violation). ERP results indicated a classical N400 effect. A wavelet-based time-frequency analysis revealed a theta band power increase during an interval of 300-800 ms after critical word onset, at temporal electrodes bilaterally for both sentence conditions, and over midfrontal areas for the semantic violations only. In the gamma frequency band, a predominantly frontal power increase was observed during the processing of correct sentences. This effect was absent following semantic violations. These results provide a characterization of the oscillatory brain dynamics, and notably of both theta and gamma oscillations, that occur during language comprehension.     

Affective priming of nonaffective semantic categorization responses

Recent studies have shown that robust affective priming effects can be obtained when participants are required to categorize the targets on the basis of their valence, but not when participants are asked to categorize the targets on the basis of nonaffective features. On the basis of this pattern of results, it has been argued that affective priming is due to processes that operate at a response selection stage rather than to processes that operate at an encoding stage. We demonstrate (a) that affective priming of nonaffective semantic categorization responses can be obtained when participants assign attention to the affective stimulus dimension, and (b) that affective priming in the standard evaluative categorization task is strongly reduced when participants assign attention to nonaffective stimulus features. On the basis of these findings, we argue (a) that processes operating at an encoding stage do contribute to the affective priming effect, and (b) that automatic affective stimulus processing is reduced when participants selectively attend to nonaffective stimulus features.     

British semantic differential responses on world powers

Investigating stereotypes associated with world powers, 28 men and 28 women at a British university rated 24 world powers using the semantic differential. Significance tests show the relationship of the powers to concepts assumed to measure the Evaluative, Potency, and Activity factors. Three-dimensional models show the relative positioning by men and by women. Results indicate (1) general agreement between men and women; (2) superpowers close to BAD and STRONG; (3) countries associated with war and strife closer to BAD, WEAK, and PASSIVE. Comparisons were made with an American sample. The need for doing further stereotype studies over time was stressed.     

Brain responses to lexical-semantic priming in children at-risk for dyslexia

Deviances in early event-related potential (ERP) components reflecting auditory and phonological processing are well-documented in children at familial risk for dyslexia. However, little is known about brain responses which index processing in other linguistic domains such as lexicon, semantics and syntax in this group. The present study investigated effects of lexical-semantic priming in 20- and 24-month-olds at-risk for dyslexia and typically developing controls in two ERP experiments. In both experiments an early component assumed to reflect facilitated lexical processing for primed words was enhanced in the at-risk group compared to the control group. Moreover, an N400-like response which was prominent in the control group was attenuated or absent in at-risk children. Results suggest that deficiencies in young children at-risk for dyslexia are not restricted to perceptual and lower-level phonological abilities, but also affect higher order linguistic skills such as lexical and semantic processing.     

Language processing in bilinguals

The present study investigated the language processing strategies of three subgroups of adult bilinguals with different histories of language acquisition: infant bilinguals whose bilinguality dated from infancy; childhood bilinguals who became bilingual around 5 years of age; and adolescent bilinguals who had become bilingual at secondary school age only. All were completely balanced bilinguals in French and English at the time of testing. The experimental procedure, a language recognition task, required the subjects to indicate, by pressing a response button, whether each of a series of words, presented monaurally through earphones, was French or English. Concomitantly, left and right hemisphere EEG activity was monitored, with measures taken of latency to N₁, latency to P₂, and N₁-P₂ peak-to-peak amplitudes. Results indicated shorter latencies to N₁ in the left than in the right hemisphere for the infant and childhood bilinguals but shorter latencies in the right hemisphere for the adolescent bilinguals. Overall, the N₁ latency was shorter for the adolescent subgroup than for the two other subgroups. There were no RT differences. The findings appear to reflect strategy differences: The adolescent group seemed to rely more on a right hemisphere-based, possibly more gestalt-like or melodic strategy, while the early bilinguals relied more on a left hemisphere-based, possibly semantic or analytic type of strategy. The results are discussed in terms of previous research on bilingual subtypes and general forms of language processing among bilinguals.