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• The findings highlight the semantic relation and grammatical factor in the brain's representation of lexical ambiguities. • Compared to unambiguous words, homonyms and polysemous activate the inferior frontal gyri and posterior temporal region. • Compared to polysemous words, homonyms elicit increased activity in dorsal prefrontal and posterior parietal cortices. • Meanings of homonyms with different syntactic categories are represented distinctively in frontal and temporal cortices. In human languages, it is a common phenomenon for a single word to have multiple meanings. This study used fMRI to investigate how the brain processed different types of lexical ambiguity, and how it differentiated the meanings of ambiguous words. We focused on homonyms and polysemy that differed in the relatedness among multiple meanings. Participants (N = 35) performed a prime-target semantic relatedness task, where a specific meaning of an ambiguous word was primed. Results showed that homonyms elicited greater activation in bilateral dorsal prefrontal and posterior parietal cortices than polysemous words, suggesting that these regions may be more engaged in cognitive control when the meanings of ambiguous words are unrelated. Multivariate pattern analysis further revealed that meanings of homonyms with different syntactic categories were represented differently in the frontal and temporal cortices. The findings highlighted the importance of semantic relations and grammatical factors in the brain's representation of lexical ambiguities. [ABSTRACT FROM AUTHOR]

• We examined the relationship between conceptual and lexical representations. • Participants viewed a sequence of 2 pictures and decided if they were related. • Some of the object names were ambiguous in orthography, phonology, or both. • N400 revealed that the lexical status of the self generated object names affected semantic decisions. • N230 revealed that conceptual access occurred 200 ms before lexical effects. We examined whether meanings automatically activate linguistic forms, and whether these forms affect semantic decisions. Participants were presented sequentially with pairs of pictures and decided whether the objects in the pictures were related. At no point did they name the pictures. The object names of the experimental stimuli were ambiguous either in orthography (homographs), phonology (homophones), or both (homonyms), or unambiguous. We show that the lexical characteristics of the name of the objects affect a semantic decision about real world relations, in an online measure (N400), in addition to offline behavioral measures. We show a dissociation between conceptual and lexical recognition, where an earlier component (N230), was affected by relatedness, but was not sensitive to the lexical characteristics. We interpret this as supporting the hypothesis that semantic recognition occurs before the automatic lexical activation of the object name, but that once linguistic representations are activated, they affect semantic integration. [ABSTRACT FROM AUTHOR]

To successfully comprehend a sentence that contains a homonym, readers must select the ambiguous word's context-appropriate meaning. The outcome of this process is influenced both by top-down contextual support and bottom-up, word-specific characteristics. We examined how these factors jointly affect the neural signatures of lexical ambiguity resolution. We measured the similarity between multi-voxel patterns evoked by the same homonym in two distinct linguistic contexts: once after subjects read sentences that biased interpretation toward each homonym's most frequent, dominant meaning, and again after interpretation was biased toward a weaker, subordinate meaning. We predicted that, following a subordinate-biasing context, the dominant yet inappropriate meaning would nevertheless compete for activation, manifesting in increased similarity between the neural patterns evoked by the two word meanings. In left anterior temporal lobe (ATL), degree of within-word pattern similarity was positively predicted by the association strength of each homonym's dominant meaning. Further, within-word pattern similarity in left ATL was negatively predicted by item-specific responses in a region of left ventrolateral prefrontal cortex (VLPFC) sensitive to semantic conflict. These findings have implications for psycholinguistic models of lexical ambiguity resolution, and for the role of left VLPFC function during this process. Moreover, these findings demonstrate the utility of item-level, similarity-based analyses of fMRI data for our understanding of competition between co-activated word meanings during language comprehension. [ABSTRACT FROM AUTHOR]

Psycholinguistic research demonstrates that representational distance between meanings influences recognition of ambiguous words. Our goal was to investigate whether the neural correlates of ambiguity are also modulated by representational distance as a function of syntactic similarity (i.e., grammatical class) and meaning dominance. In an event-related fMRI experiment, participants completed a visual lexical decision task that included balanced and unbalanced noun–noun and noun–verb homonyms, unambiguous words, and nonwords. Syntactic similarity effects were observed in left inferior frontal regions, with greater activation for noun–verb than noun–noun homonyms. Meaning dominance effects were observed in left middle and superior temporal regions, with greater activation for balanced than unbalanced homonyms. These findings indicate that the behavioral cost associated with processing ambiguous word meanings, modulated by syntactic similarity and meaning dominance, is reflected in the neural systems underlying ambiguity processing, as frontal and temporal regions are recruited by increased competition as a function of representational distance. [ABSTRACT FROM AUTHOR]

Highlights: [•] Event-related fMRI investigated the contribution of the right hemisphere in linguistic tasks. [•] Bilateral involvement of the pars opercularis (Brodmann’s area 44). [•] Bilateral involvement of the supramarginal gyrus of the inferior parietal lobule. [•] Strong connections between areas 44 and 40 through SLF III. [•] Delineate anterior-posterior language processing system bilaterally. [•] Increased right hemisphere involvement during metaphorical interpretations. [ABSTRACT FROM AUTHOR]

Abstract: The time-line of lexical ambiguity resolution in bilateral neuronal networks was investigated using magnetoencephalography (MEG) in a semantic decision task. Dominant and subordinate associations of ambiguous words are considered to be processed in the left and right hemispheres, respectively. In the experiment, ambiguous words were followed by dominant or subordinate associations (manipulated between blocks) or by unrelated target words, and participants (N=25) decided whether the words in each pair were related or not. Subordinate meaning blocks elicited greater changes in the magnetic fields relative to dominant ones over the right, but not the left hemisphere (LH) at 150–235ms from target onset, a time window corresponding to the M/N170 M/EEG component. Beamforming analysis localized the differential right hemisphere (RH) activity at the perisylvian area, including the homologue regions of Broca's and Wernicke's. At a later stage (235–390ms) there was no significant difference between the two meaning conditions. We suggest that the RH language regions assist the LH in integrating subordinate disambiguating clues to preceding context during the M170 time window. [Copyright &y& Elsevier]

Abstract: Event-related potentials (ERPs) were used to investigate the time-course of meaning activation of different types of ambiguous words. Unbalanced homonymous (“pen”), balanced homonymous (“panel”), metaphorically polysemous (“lip”), and metonymically polysemous words (“rabbit”) were used in a visual single-word priming delayed lexical decision task. The theoretical distinction between homonymy and polysemy was reflected in the N400 component. Homonymous words (balanced and unbalanced) showed effects of dominance/frequency with reduced N400 effects predominantly observed for dominant meanings. Polysemous words (metaphors and metonymies) showed effects of core meaning representation with both dominant and subordinate meanings showing reduced N400 effects. Furthermore, the division within polysemy, into metaphor and metonymy, was supported. Differences emerged in meaning activation patterns with the subordinate meanings of metaphor inducing differentially reduced N400 effects moving from left hemisphere electrode sites to right hemisphere electrode sites, potentially suggesting increased involvement of the right hemisphere in the processing of figurative meaning. [Copyright &y& Elsevier]

Abstract: Unlike homophonous meanings, which are semantically unrelated (e.g., the use of bat to refer to a baseball bat and a flying rodent), polysemous meanings are systematically related to one another (e.g., the use of book, CD, and video to refer to physical objects, as in ‘the leather book’, or to the intellectual content they contain, as in ‘the profound book’). But do perceived relations among polysemous meanings reflect the presence of generative lexical or conceptual structures that permit the meanings of these words to shift? If so, these structures may also support children’s early representations of polysemous meanings. In four studies, we demonstrate (1) that four-year-old children can understand both the concrete and abstract meanings of words like book, (2) that when taught a novel label for one of these meanings, children can readily understand an extension of that label to the other meaning, and (3) that extension does not occur between two homophonous meanings, which share a common phonological form but are otherwise unrelated. We conclude that the polysemous meanings of words like book rely on a common representational base early in development, and suggest that this may be the result of foundational, generative properties of the lexicon or conceptual system. [Copyright &y& Elsevier]

Abstract: This study investigates the contribution of the left and right hemispheres to the comprehension of bilingual figurative language and the joint effects of salience and context on the differential cerebral involvement in idiom processing. The divided visual field and the lexical decision priming paradigms were employed to examine the activation of salient and nonsalient ambiguous idiom interpretations (i.e., literal vs. non-literal) in the two hemispheres. Literally plausible ambiguous idioms, L1 (Polish) and L2 (English), were embedded in unconstraining ambiguous (e.g., I knew he kept an ace up his sleeve) or constraining unambiguous context clearly favoring their conventional idiomatic interpretation (e.g., The debating president kept an ace up his sleeve). Idioms were presented centrally, followed by laterally presented targets related to the figurative (e.g., GAIN) or literal (e.g., SHIRT) meaning of the idiom and displayed at Interstimulus Intervals (ISIs) of 0ms (Experiment 1), 300ms (Experiment 2), and 800ms (Experiment 3). Results indicate that context and salience effects are significantly modulated by the language (native vs. nonnative) of the stimulus materials being presented to each hemisphere. Literal facilitation was found for L2 idioms in all three ISI conditions, which supports the notion of the special status that literal meanings of L2 idioms enjoy in the course of their processing by nonnative language users. No significant differences were found between the right and left hemispheres in regards to their sensitivity to contextual constraints. Results are discussed in terms of the Graded Salience Hypothesis and the Fine/Coarse Coding Theory. [Copyright &y& Elsevier]

Abstract: The role of attentional control in lexical ambiguity resolution was examined in two patients with damage to the left inferior frontal gyrus (LIFG) and one control patient with non-LIFG damage. Experiment 1 confirmed that the LIFG patients had attentional control deficits compared to normal controls while the non-LIFG patient was relatively unimpaired. Experiment 2 showed that all three patients did as well as normal controls in using biasing sentence context to resolve lexical ambiguities involving balanced ambiguous words, but only the LIFG patients took an abnormally long time on lexical ambiguities that resolved toward a subordinate meaning of biased ambiguous words. Taken together, the results suggest that attentional control plays an important role in the resolution of certain lexical ambiguities – those that induce strong interference from context-inappropriate meanings (i.e., dominant meanings of biased ambiguous words). [ABSTRACT FROM AUTHOR]

Abstract: Neuroimaging studies have shown that the left inferior frontal gyrus (LIFG) plays a critical role in semantic and syntactic aspects of speech comprehension. It appears to be recruited when listeners are required to select the appropriate meaning or syntactic role for words within a sentence. However, this region is also recruited during tasks not involving sentence materials, suggesting that the systems involved in processing ambiguous words within sentences are also recruited for more domain-general tasks that involve the selection of task-relevant information. We use a novel dual-task methodology to assess whether the cognitive system(s) that are engaged in selecting word meanings are also involved in non-sentential tasks. In Experiment 1, listeners were slower to decide whether a visually presented letter is in upper or lower case when the sentence that they are simultaneously listening to contains words with multiple meanings (homophones), compared to closely matched sentences without homophones. Experiment 2 indicates that this interference effect is not tied to the occurrence of the homophone itself, but rather occurs when listeners must reinterpret a sentence that was initially misparsed. These results suggest some overlap between the cognitive system involved in semantic disambiguation and the domain-general process of response selection required for the case-judgement task. This cognitive overlap may reflect neural overlap in the networks supporting these processes, and is consistent with the proposal that domain-general selection processes in inferior frontal regions are critical for language comprehension. [ABSTRACT FROM AUTHOR]

Abstract: Previous research suggests that the left hemisphere (LH) focuses on strongly related word meanings; the right hemisphere (RH) may contribute uniquely to the processing of lexical ambiguity by activating and maintaining a wide range of meanings, including subordinate meanings. The present study used the word-lists false memory paradigm [Roediger, H. L. III., & McDermott, K. B. (1995). Creating false memories: Remembering words not presented in lists. Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 803–814.] to examine whether these differences between the two cerebral hemispheres in semantic processing also affect memory representations for different meanings of ambiguous words. Specifically, we tested the differences between the LH and RH in recollecting unpresented, semantically related, ambiguous words following the presentation of lists of words all related to either the dominant or the subordinate meanings of these ambiguous words. Findings showed that for the unpresented ambiguous words, the LH made more false alarms than the RH for the dominant lists, whereas the opposite pattern emerged for subordinate lists. Moreover, d′ analyses showed that, whereas the LH was more sensitive to subordinate than dominant meanings, the RH showed no differences in sensitivity for the two types of word–lists. Taken as a whole, these results support the RH coarse semantic coding theory [Beeman, M. (1998). Coarse semantic coding and discourse comprehension. In Beeman & M., Chiarello, C. (Eds.), Right hemisphere language comprehension: Perspectives from cognitive neuroscience (pp. 255–284). Mahwah, NJ: Erlbaum; Jung-Beeman, M. (2005). Bilateral brain processes for comprehending natural language. Trends in Cognitive Sciences, 9, 512–518.] indicating that during word recognition, the RH activates and maintains a broader and less differentiated range of related meanings than the LH, including both dominant and subordinate meanings of ambiguous words. Furthermore, the findings suggest that hemispheric differences in ambiguity resolution during language processing extend also to verbal memory. [Copyright &y& Elsevier]

Abstract: The present study examined the manner in which both hemispheres utilize prior semantic context and relative meaning frequency during the processing of homographs. Participants read sentences biased toward the dominant or the subordinate meaning of their final homograph, or unbiased neutral sentences, and performed a lexical decision task on lateralized targets presented 250ms after the onset of the sentence-final ambiguous prime. Targets were either related to the dominant or the subordinate meaning of the preceding homograph, or unrelated to it. Performance asymmetry was found in the absence of a biasing context: dominant-related targets were exclusively facilitated in the RVF/LH, whereas both dominant- and subordinate-related targets were facilitated in the LVF/RH. Performance symmetry was found in the presence of a biasing context: dominant-related targets were exclusively activated in dominant-biasing contexts, whereas both dominant- and subordinate-related targets were facilitated in subordinate-biasing contexts. The implications of the results for both general and hemispheric models of word processing are discussed. [Copyright &y& Elsevier]

Abstract: To clarify the neural mechanisms of lexical access and selection of contextually appropriate meanings for ambiguous words, we investigated the spatio-temporal characteristics of neural activities during silent reading and semantic judgment of lexically ambiguous or unambiguous target words that were preceded by semantically related or unrelated words by using magnetoencephalography. The left posterior superior temporal/inferior parietal area and the left anterior middle/inferior temporal area consistently showed a clear context effect, regardless of the ambiguity: the activities for related words were weaker than those for unrelated words. The activities in the left inferior frontal cortex, in contrast, were influenced by ambiguities. From ∼200 to 300 ms, the activities in the left anterior inferior frontal cortex (aIFC) were stronger for ambiguous words than for unambiguous words, regardless of context. The stronger activities in the left aIFC, reflecting an increase in controlled semantic retrieval, indicate that multiple meanings for lexically ambiguous words are accessed irrespective of context. At ∼400 ms, the left posterior inferior frontal cortex (pIFC) showed a clear context effect for unambiguous words but not for ambiguous ones. In addition, the activation in the left pIFC was stronger for related ambiguous words than for related unambiguous ones. These results suggest that in ambiguous words, not only contextually appropriate meanings but also two or more inappropriate meanings would be semantically integrated with a context. We conclude that the left IFC plays an important role in selecting an appropriate meaning from multiple alternatives after the integration of contextual information. [Copyright &y& Elsevier]

Abstract: The function of suppression of context-inappropriate meanings during lexical ambiguity resolution was examined in 25 adults with prefrontal cortex damage (PFCD) localized to the left (N =8), right (N =6), or bilaterally (N =11); and 21 matched Controls. Results revealed unexpected inverse patterns of suppression between PFCD and Control groups, with measures suggesting decreased interference across time in the PFCD group and increased interference in the Control group. The PFCD group, however, had significantly lower accuracy rates for the context-inappropriate condition. Results suggest a loss of the control aspects of inhibitory processes in lexical ambiguity resolution following PFCD. An aging effect on suppression function is also suggested. [Copyright &y& Elsevier]

Abstract: The present study investigated the abilities of left-hemisphere-damaged (LHD) non-fluent aphasic, right-hemisphere-damaged (RHD), and normal control individuals to access, in sentential biasing contexts, the multiple meanings of three types of ambiguous words, namely homonyms (e.g., “punch”), metonymies (e.g., “rabbit”), and metaphors (e.g., “star”). Furthermore, the predictions of the “suppression deficit” and “coarse semantic coding” hypotheses, which have been proposed to account for RH language function/dysfunction, were tested. Using an auditory semantic priming paradigm, ambiguous words were incorporated in dominant- or subordinate-biasing sentence-primes followed after a short (100ms) or long (1000ms) interstimulus interval (ISI) by dominant-meaning-related, subordinate-meaning-related or unrelated target words. For all three types of ambiguous words, both the effects of context and ISI were obvious in the performance of normal control subjects, who showed multiple meaning activation at the short ISI, but eventually, at the long ISI, contextually appropriate meaning selection. Largely similar performance was exhibited by the LHD non-fluent aphasic patients as well. In contrast, RHD patients showed limited effects of context, and no effects of the time-course of processing. In addition, although homonymous and metonymous words showed similar patterns of activation (i.e., both meanings were activated at both ISIs), RHD patients had difficulties activating the subordinate meanings of metaphors, suggesting a selective problem with figurative meanings. Although the present findings do not provide strong support for either the “coarse semantic coding” or the “suppression deficit” hypotheses, they are viewed as being more consistent with the latter, according to which RH damage leads to deficits suppressing alternative meanings of ambiguous words that become incompatible with the context. [Copyright &y& Elsevier]

Using an auditory semantic priming paradigm, the present study investigated the abilities of left-hemisphere-damaged (LHD) non-fluent aphasic-right-hemisphere-damaged (RHD) and normal control individuals to access, out of context, the multiple meanings of three types of ambiguous words, namely homonyms (e.g., "punch"), metonymies (e.g., "rabbit"), and metaphors (e.g., "star"). In addition, the study tested certain predictions of the "suppression deficit" and "coarse semantic coding" hypotheses that have been proposed to account for the linguistic deficits typically observed after RH damage. Homonymous, metonymous, and metaphorical words were used as primes followed after a short (100 ms) or a long (1000 ms) inter-stimulus interval (ISI) by dominant-meaning-related, subordinate-meaning-related or unrelated target words. No significant group effects were found, and for both ISIs, dominant- and subordinate-related targets were facilitated relative to unrelated control targets for the homonymy and metonymy conditions. In contrast, for the metaphor condition, only targets related to the dominant meaning were facilitated. These findings provide only partial support for the "suppression deficit" hypothesis and no support for the "coarse semantic coding" hypothesis (as interpreted herein) indicating that patients with focal LH or RH damage can access the multiple meanings of ambiguous words and exhibit processing abilities comparable to those of older normal control subjects, at least at the single-word level. [ABSTRACT FROM AUTHOR]

The current study examines how patients with aphasia access the meanings of idioms during spoken sentence comprehension. In our experiment, we had 4 subjects whose native language is German: 2 left-hemisphere damaged patients (Wernicke’s and global aphasia); 1 right-hemisphere damaged patient; and 1 age-matched healthy speaker. Ambiguous two-element German noun compounds carrying an idiomatic as well as a literal meaning served as target words. While listening to contextually biasing sentences containing the target words, the subjects performed a lexical decision task at the offset of each compound. All the subjects, including the aphasic patients, accessed the compounds’ literal and idiomatic meanings simultaneously despite the existence of contextually biasing sentences. The data are discussed by taking account of the findings of recent studies of lexical semantic processing in aphasia. [Copyright &y& Elsevier]

The present lexical decision task experiment examined orthographic (large, medium, small), number-of-meanings (ambiguous, unambiguous), and number of higher frequency neighbors (few, many), factors that have to date not been studied simultaneously. For both mean reaction time and percentage error, the critical three-way interaction between these factors was significant. Breakdown of this interaction revealed that the ambiguity effect (unambiguous–ambiguous) decreased as neighborhood size increased, but only when there were many higher frequency neighbors in the neighborhood. These results appear inconsistent with serial search models but are understandable within the context of interactive-activation models of word recognition. [Copyright &y& Elsevier]

Under the theoretical assumption that lexical ambiguity is not a homogeneous phenomenon, but rather that it is subdivided into two distinct types, namely homonymy and polysemy, the present study investigated whether these different types of lexical ambiguity are psychologically real. Four types of ambiguous words, homonymous words (e.g., “pen”), polysemous words with metaphorical extensions (e.g., “eye”), polysemous words with a count/mass metonymic extension (e.g., “turkey”), and polysemous words with a producer/product metonymic extension (e.g., “Dali”), were used in a cross-modal sentence-priming lexical decision task. Overall, the theoretical distinction between homonymy and polysemy was reflected in the results of the present study, which revealed differential processing depending on the type of ambiguity. [Copyright &y& Elsevier]

A priming experiment was used to investigate Burgess and Simpson''s (1988) claim that interhemispheric cooperation plays an essential role in the interpretation of ambiguous text. In doing so, the merits of two models of interhemispheric cooperation, the homotopic inhibition theory (Cook, 1986) and the direct connections model (Collins & Coney, 1998), were examined. Priming of alternative meanings of ambiguous words was measured using homographs and their dominant (e.g., BARK–DOG) and subordinate meanings (e.g., BARK–TREE) as related pairs in a lexical decision task, with normal university students as subjects. Stimulus pairs were temporally separated by stimulus onset asynchronies (SOAs) of 180 and 350 ms and were independently projected to the left or right visual fields (LVF or RVF). At the shorter SOA, priming was restricted to LVF–RVF presentations, with homograph primes directed to the LVF equally facilitating responses to RVF targets which were associated with their dominant and subordinate meanings. This suggests that within 180 ms, a homograph projected to the right hemisphere activates a range of alternative meanings in the left hemisphere. At an SOA of 350 ms, LVF–RVF priming was obtained along with RVF–LVF and RVF–RVF priming. Evidently at this stage of processing, an ambiguous word directed to either hemisphere activates a range of alternative meanings in the contralateral hemisphere, while RVF primes also activate subordinate, but not dominant meanings in the left hemisphere. A homograph directed to the LVF did not activate dominant or subordinate meanings within the right hemisphere at either SOA. Generally, ambiguous words directed to either hemisphere activated a more extensive array of meanings in the contralateral hemisphere than in the hemisphere to which the prime was directed. This confirms the importance of interhemispheric cooperation in generating alternate meanings of ambiguous words. Strong support was found for the direct connections model (Collins & Coney, 1998), but no support for the homotopic inhibition theory (Cook, 1986). [Copyright &y& Elsevier]