Unambiguous Nouns Research Articles

Сопоставительный анализ английской и русской речи через иерархии релевантности

The article discusses similarities and dissimilarities between the communication patterns of native speakers of the Russian and English languages in two geographically separated regions based on the transcripts of podcasts, TV and radio broadcasts for the audiences of Russia and the USA. Here we advance a hypothesis that such patterns can be represented in a hierarchical form. Using the occurrence rates of Russian and English lexical units, hierarchies are built, referred to as the relevance hierarchies. These structures based on the texts in the two languages are compared to identify notions, phenomena and topics that are the most relevant in the language communities under consideration and thus give an insight into the current worldview of native speakers. Additionally, we carry out a morphological analysis of the first 500 units and divide them by parts of speech in both languages’ hierarchies. We determine the occurrence rates of individual grammatical categories in the compared sets of texts. On the given scale, the so-called grammatically unambiguous nouns and verbs are listed and correlated for the two languages. We point out the most relevant notions in the English and Russian discourses, draw parallels and note differences. The paper is concluded by possible explanations and views about language-specific characteristics, as well as by remarks on some stylistic peculiarities in native speakers’ use of their respective mother tongues. Finally, we outline potential areas of further study by stressing the importance of context-based analysis and present our research method in the form of a Web tool as an initial step in this direction.

Характеристика мовної особистості президента США Дональда Трампа

The article analyzes the linguistic personality of President Donald Trump, taking into account this status in political discourse. The president, as an elected representative of power, acts primarily in certain communication genres, and the content of his speeches, statements, appeals reflects both the policy of the state in general in a certain period of time, and specific political intentions. Thus, even within the limits of the regulated political discourse in modern conditions of communication individual features of the person as the president of the country are seen. The article analyzes Trump’s speeches and tweets in terms of their lexical, syntactic, and epideictic content, highlights the key words that denote the basic concepts of President Trump’s activities and serve as a means of rhetorical influence. The article presents and analyses the key words in Trump’s speeches. They are as follows: America, Americans, democracy, success, president, to defend, hounorable, responsibility, to promise, which, in general, help to form the image of the President who is ready to take responsibility for the democratic values of Americans. The traditional topics of the President’s speeches are finance, war and peace, protection of the country, its food and legislation. Syntactically, Trump’s speeches and statements are characterized by the use of simple, short sentences, in the content of which there is the use of simple, unambiguous nouns with the strong emotional meaning – fear, pride, crisis, dream, success. As a means of rhetorical influence, Trump places the most meaningful positions of his speeches at the end of sentences with logical emphasis on them. A lot of points in Trump’s speeches are the expressions of gratitude, jokes, references, and other means of establishing the connection with the audience and expressing hi own personal position. A feature of the linguistic personality in modern communication is the use of social networks, where there may be some deviations from the formalized institutional political discourse in terms of grammar and style, and this fact as clearly as possible also characterizes Trump’s language personality. For political discourse, especially in the country with the democratic values, the reaction of the society, feedback from the people of a government official’s activities is important, and social networks can fully provide the people’s immediate response to the President’s activity, so the communication can be full, not one-sided.

BALANCE OF MEANING PROBABILITIES IN PROCESSING OF SERBIAN HOMONYMY

The research deals with the set of Serbian homonymous nouns (nouns with multiple unrelated meanings) presented in the norming study and in the visual lexical decision task experiment. Native speakers listed the meanings of homonymous words and provided word familiarity and word concreteness ratings. Accordingly, the first database of Serbian homonyms was constructed containing subjective meanings of homonymous nouns along with the estimated meaning probabilities, as well as a number of meanings, redundancy and entropy of the distribution of meaning probabilities, word familiarity and word concreteness. The processing disadvantage of homonymous nouns over unambiguous nouns was replicated in the visual lexical decision task. Additionally, the processing of homonymous nouns was linked with redundancy: the information theory measure of the balance of meaning probabilities. The results revealed that homonyms with higher redundancy of the meaning probability distribution (i.e., unbalanced meaning probabilities) were processed faster. This finding was in accordance with the hypothesis derived from the Semantic Settling Dynamics account of the processing of ambiguous words, according to which the competition among the unrelated meanings derived the processing disadvantage in homonymy. However, the same pattern was not observed for the number of meanings and entropy, inviting for further research of the processing of ambiguous words.

EEG source reconstruction evidence for the noun-verb neural dissociation along semantic dimensions

One of the long-standing issues in neurolinguistic research is about the neural basis of word representation, concerning whether grammatical classification or semantic difference causes the neural dissociation of brain activity patterns when processing different word categories, especially nouns and verbs. To disentangle this puzzle, four orthogonalized word categories in Chinese: unambiguous nouns (UN), unambiguous verbs (UV), ambiguous words with noun-biased semantics (AN), and ambiguous words with verb-biased semantics (AV) were adopted in an auditory task for recording electroencephalographic (EEG) signals from 128 electrodes on the scalps of twenty-two subjects. With the advanced current density reconstruction (CDR) algorithm and the constraint of standardized low-resolution electromagnetic tomography, the spatiotemporal brain dynamics of word processing were explored with the results that in multiple time periods including P1 (60–90ms), N1 (100–140ms), P200 (150–250ms) and N400 (350–450ms), noun–verb dissociation over the parietal-occipital and frontal-central cortices appeared not only between the UN-UV grammatical classes but also between the grammatically identical but semantically different AN-AV pairs. The apparent semantic dissociation within one grammatical class strongly suggests that the semantic difference rather than grammatical classification could be interpreted as the origin of the noun–verb neural dissociation. Our results also revealed that semantic dissociation occurs from an early stage and repeats in multiple phases, thus supporting a functionally hierarchical word processing mechanism.

Kontinuirano upućivanje na žive i nežive entitete u pisanom diskursu

The aim of this paper is to analyse referential continuity in written discourse. Holding a view that referring to an entity depends on the nature of the entity itself, we analysed reference to animate and inanimate entities separately. One of the characteristics of language is its referential function which helps us not only to identify referents but to refer to them continuously using a wide spectrum of referring expressions from unambiguous noun phrases and repetition to personal pronouns and demonstratives. The efficiency of establishing and maintaining referential continuity is assessed with the ability of readers to identify and track referents in text. The text we used for the analysis is a narrative story in English and Serbian.

Processing anomalous anaphors.

Previous researchers have demonstrated that readers may engage in shallow, or incomplete, processing when the semantic overlap between current information and previously encountered information is high. The present study investigated whether these effects would occur during processing of unambiguous noun phrase anaphors, for which there was only a single possible antecedent. Participants read passages containing anaphors that were correct, incorrect but highly related, or incorrect and low-related, with respect to previously encountered information. The time required to process the anaphor was a function of the goodness of fit between the anaphor and the antecedent; anaphors that were incorrect but highly related to the antecedent were processed more quickly than those that were incorrect and low-related. This occurred regardless of the distance between the anaphor and the antecedent. However, reading times results from a spillover sentence indicated that readers subsequently validated the anaphor against the information in memory, resulting in continued processing difficulty for both the incorrect-high- and -low-related anaphor conditions. The results are consistent with a three-stage comprehension model in which information is activated, integrated on the basis of its goodness of fit with the contents of working memory, and then validated against information in long-term memory.

Abnormal N400 responses but intact differential hemispheric processing of ambiguity in schizophrenia

Disordered thinking in schizophrenia may be a consequence of the selection of conceptual associates of dominant meanings of ambiguous words despite contextual information suggesting subordinate meanings are more appropriate. Previous work using short sentences showed a large N400 event-related potential to subordinate meaning associates and a behavioral semantic bias, but results were variable. The current experiment used word pairs to simplify the procedure and to less tax memory maintenance. Furthermore, hemispheric responses were compared, as evidence suggests the left hemisphere may select dominant meanings, while the right hemisphere may keep all possible meanings active. Subjects indicated whether two words (CUE, TARGET) were related. The CUE, presented for 1 s, could be an ambiguous or an unambiguous noun, and the TARGET, presented 1.25 s after the onset of the CUE, was a dominant or subordinate associate, or a related or an unrelated word, respectively. The N400-effect was calculated from difference waveforms over 400–600 ms. Groups (23 schizophrenia, 25 matched controls) showed significantly different N400-effects to the words (group × word, p = 0.04). Controls showed a graded response, with dominant < subordinate < unrelated. Schizophrenia patients showed the largest N400-effect to subordinate associates, with less activity to dominant meaning associates and unrelated words. Both groups showed a right hemisphere distribution to unrelated words and substantial left hemisphere activation to subordinate associates (word × hemisphere, p < 0.001). These data support a semantic bias in schizophrenia. They also demonstrate a special role of the right hemisphere in maintaining broad homograph meaning hierarchies. This hemispheric specialization appears to be intact in schizophrenia.

N400 to lexical ambiguity and semantic incongruity in schizophrenia

Our previous work showed a semantic bias in interpreting ambiguous words in schizophrenia, with disproportionate misinterpretation of subordinate meanings ( toast at a wedding). We proposed pre-selection in schizophrenia of dominant-meaning networks at points of lexical ambiguity, thereby misleading thought. This selection bias may be due to semantic memory hyper-priming causing strong associates to dominate cognition. Alternately, later verbal memory maintenance failure may cause weaker associates to fade more quickly than stronger associates from memory due to less initial activation. To further examine this semantic bias, patients and controls were presented short 4 word long sentences (The toast was buttered). The second word was a homograph or unambiguous noun. The last word disambiguated homographs (dominant or subordinate meaning) or was congruent or incongruent with unambiguous nouns. Previously, we showed increasingly larger N400 from unambiguous associates to dominate associates to subordinate associates to unambiguous non-associates in controls. Pre-selection of dominant meanings predicts that schizophrenia patients would show small N400 to dominant associates and as large N400 to subordinate associates as to incongruous endings. Here, controls again showed graded N400 amplitudes. Patients with schizophrenia showed small N400 to congruent and dominant endings and large N400 to subordinate and incongruous endings. These data suggest early pre-selection of dominant associates in schizophrenia. This effect is unlikely solely due to verbal memory maintenance failure, as patients were able to detect incongruity, albeit with a smaller N400 effect, and displayed generally larger N400 to all stimuli. These results suggest alterations in semantic memory associative networks coupled with verbal working memory maintenance decay in schizophrenia.

Ambiguity Advantage Revisited: Two Meanings are Better than One When Accessing Chinese Nouns

This paper revisits the effect of lexical ambiguity in word recognition, which has been controversial as previous research reported advantage, disadvantage, and null effects. We discuss factors that were not consistently treated in previous research (e.g., the level of lexical ambiguity investigated, parts of speech of the experimental stimuli, and the choice of non-words) and report on a lexical decision experiment with Chinese nouns in which ambiguous nouns with homonymic and/or metaphorical meanings were contrasted with unambiguous nouns. An ambiguity advantage effect was obtained-Chinese nouns with multiple meanings were recognized faster than those with only one meaning. The results suggested that both homonymic and metaphorical meanings are psychologically salient semantic levels actively represented in the mental lexicon. The results supported a probability-based model of random lexical access with multiple meanings represented by separate semantic nodes. We further discuss these results in terms of lexical semantic representation and how different experimental paradigms result in different ambiguity effects in lexical access.

Functional neuroimaging of grammatical class: Ambiguous and unambiguous nouns and verbs

Neuropsychological and neuroimaging studies of grammatical-class differences suggest that nouns and verbs may be associated with different brain regions. The current functional magnetic resonance imaging (fMRI) study focused on auditory grammaticality judgements of two-word stimuli consisting of noun/verb ambiguous and unambiguous nouns and verbs preceded by either “the” or “to”. The fMRI results showed effects of class ambiguity in the left inferior frontal gyrus, possibly due to greater selection demands, and effects of grammaticality (“yes” vs. “no” response) in left superior temporal gyrus, consistent with greater activation for trials with greater conflict. In addition, posterior left temporal lobe regions showed increased activity on unambiguous trials for verbs than for nouns, consistent with prior imaging studies. Thus, in a task specifically focused on the grammatical (rather than semantic) aspects of words and that used morphologically simple nouns and verbs controlled for imageability, verbs preferentially activated posterior temporal but not frontal lobe regions. However, for ambiguous trials in this same region, nouns showed greater activation than verbs, suggesting that these effects can be modulated by class ambiguity.

Neural Distinction between Chinese Nouns and Verbs in the Grammatical Context: An ERP Study

Many current researches in neurolinguistics focus on the different possible neural representations of nouns and verbs.Evidence from neuropsychological and neuroimaging studies suggests different neural representations of nouns and verbs in Indo-European languages.Specifically,verbs are represented in the frontal region,while nouns are represented in more posterior brain areas.This is consistent with the results of electrophysiological studies.In contrast to other Indo-European languages,Chinese is characterized by the lack of inflectional morphology.Some investigators argued that nouns and verbs in Chinese are not dissociable with regard to grammatical classes but rather are differentiated by their semantic properties.The current study aims to investigate whether noninflectional nouns and verbs in Chinese could be dissociated at the neural level and whether the dissociation reflects their grammatical roles. All the nouns and verbs used in the experiments were all words that were not characterized by inflectional morphology.There were three sets of stimuli used in the experiments:(1)disyllabic unambiguous nouns,(2)unambiguous verbs,and (3)noun-verb ambiguous words.These stimuli were combined with a priming word to construct two contrastive phrase contexts,namely,noun-predicting(e.g.,"yi Q +_") and verb-predicting(e.g.,"bu M +_").The subjects were asked to decide whether the presented phrase represented a legal or illegal phrase.ERPs in response to the three sets of stimuli in different contexts were recorded.The ERPs were then analyzed using a repeated-measures ANOVA. We observed significant ERP differences between nouns and verbs in intervals of 145~225ms,250~400ms,and 450~650ms.Unambiguous nouns elicited a larger P200 than did unambiguous verbs.When the context completely matched their role,unambiguous verbs elicited a larger N400 and a smaller P600 than unambiguous nouns. Similarly,ambiguous words used as nouns elicited a larger P600 than did ambiguous words used as verbs. Our results do not support the claim that nouns and verbs in Chinese are not dissociable in terms of grammatical classes.On the contrary,the results demonstrated clear ERP responses that reflect a grammatical process.We argue that although the Chinese language lacks inflectional morphology,grammatical features are embedded in nouns and verbs and function regardless of whether there are explicit grammatical signs in these words.Grammatical features play an important role in the neural processing of Chinese nouns and verbs.

Activation and maintenance of peripheral semantic features of unambiguous words after right hemisphere brain damage in adults

Background: The right cerebral hemisphere (RH) sustains activation of subordinate, secondary, less common, and/or distantly related meanings of words. Much of the pertinent data come from studies of homonyms, but some evidence also suggests that the RH has a unique maintenance function in relation to unambiguous nouns. In a divided visual field priming study, Atchley, Burgess, and Keeney (1999) reported that only left visual field/RH presentation yielded evidence of continuing activation of peripheral semantic features that were incompatible with the most common image or representation of their corresponding nouns (e.g., rotten for “apple”). Activation for weakly related features that were compatible with the dominant representation (e.g., crunchy) was sustained over time regardless of the visual field/hemisphere of initial stimulus input. Several studies report that unilateral right hemisphere brain damage (RHD) in adults affects the RH's meaning maintenance function, but this work also has centred on homonyms, and/or more recently metonymic and metaphoric polysemous words. Aims: The current investigation examined whether RHD deficits in processing secondary and/or distantly related meanings of words, typically observed in studies of homonyms, would extend to peripheral, weakly related semantic features of unambiguous nouns. Methods & Procedures: Participants were 28 adults with unilateral RHD from cerebrovascular accident, and 38 adults without brain damage. Participants listened to spoken sentences that ended with an unambiguous noun. Each sentence was followed by a spoken target phoneme string. Targets included peripheral semantic features of the sentence‐final noun that were either compatible or incompatible with the dominant mental images of the noun, and were presented at two intervals after that noun. A lexical decision task was used to gauge both the early activation and maintenance of activation for these weakly related semantic features. Outcomes & Results: Accuracy data demonstrated activation (priming) for both types of peripheral features, in both groups, shortly after presentation of the corresponding noun. Neither group evidenced continuing activation for either type of feature at a longer interval. These results are interpreted as reflecting rapid decay/poor maintenance of activation for distantly related features for both groups. The lack of a biasing context, however, did not provide an appropriate test for previously reported suppression deficits after RHD. Fast decay of activation of compatible semantic features was unexpected for the control group. Adults with RHD were less accurate than the control group at both test intervals for the features that are semantically more distant from their associated nouns (Related‐incompatible features). Accordingly, it is argued that the RHD group's poor maintenance of activation for these features reflects a deficit, rather than normal performance. The interpretation of results from this study is complicated by the lack of RT priming for either type of semantic feature, and for either participant group. Conclusions: The right cerebral hemisphere appears to be necessary for activating semantic features that are particularly distantly related to their corresponding lexical items, and for sustaining activation of these features in the absence of a biasing context. Because lexical processing has been linked with discourse comprehension for adults with RHD, more work in this area should enhance clinical management in the future.

Part-of-speech persistence: The influence of part-of-speech information on lexical processes

This paper presents three naming experiments designed to investigate whether the activation levels of syntactic features associated with lexical items, specifically part-of-speech information, can influence lexical processes. Naming preferences for orthographically ambiguous but phonologically distinct English nouns and verbs, such as convict (CONvict n vs. conVICT v) were compared. In Experiment 1, ambiguous target words were preceded by unambiguous noun, verb, and letter (control) primes. Experiments 2 and 3 were designed to distinguish whether the priming effects observed in Experiment 1 have a syntactic or a semantic locus. In all three experiments, we found an influence of the part-of-speech of the prime on speakers’ naming preferences for the target. The results support a model of the lexicon in which part-of-speech information can influence lexical processes.

Grammatical Categories in the Brain: The Role of Morphological Structure

The current study addresses the controversial issue of how different grammatical categories are neurally processed. Several lesion-deficit studies suggest that distinct neural substrates underlie the representation of nouns and verbs, with verb deficits associated with damage to left inferior frontal gyrus (LIFG) and noun deficits with damage to left temporal cortex. However, this view is not universally shared by neuropsychological and neuroimaging studies. We have suggested that these inconsistencies may reflect interactions between the morphological structure of nouns and verbs and the processing implications of this, rather than differences in their neural representations (Tyler et al. 2004). We tested this hypothesis using event-related functional magnetic resonance imaging, to scan subjects performing a valence judgment on unambiguous nouns and verbs, presented as stems ('snail, hear') and inflected forms ('snails, hears'). We predicted that activations for noun and verb stems would not differ, whereas inflected verbs would generate more activation in left frontotemporal areas than inflected nouns. Our findings supported this hypothesis, with greater activation of this network for inflected verbs compared with inflected nouns. These results support the claim that form class is not a first-order organizing principle underlying the representation of words but rather interacts with the processes that operate over lexical representations.

To mind the mind: An event-related potential study of word class and semantic ambiguity

The goal of this study was to jointly examine the effects of word class, word class ambiguity, and semantic ambiguity on the brain response to words in syntactically specified contexts. Four types of words were used: (1) word class ambiguous words with a high degree of semantic ambiguity (e.g., ‘duck’); (2) word class ambiguous words with little or no semantic ambiguity (e.g., ‘vote’); (3) word class unambiguous nouns (e.g., ‘sofa’); and (4) word class unambiguous verbs (e.g., ‘eat’). These words were embedded in minimal phrases that explicitly specified their word class: “the” for nouns (and ambiguous words used as nouns) and “to” for verbs (and ambiguous words used as verbs). Our results replicate the basic word class effects found in prior work (Federmeier, K.D., Segal, J.B., Lombrozo, T., Kutas, M., 2000. Brain responses to nouns, verbs and class ambiguous words in context. Brain, 123 (12), 2552–2566), including an enhanced N400 (250–450 ms) to nouns compared with verbs and an enhanced frontal positivity (300–700 ms) to unambiguous verbs in relation to unambiguous nouns. A sustained frontal negativity (250–900 ms) that was previously linked to word class ambiguity also appeared in this study but was specific to word class ambiguous items that also had a high level of semantic ambiguity; word class ambiguous items without semantic ambiguity, in contrast, were more positive than class unambiguous words in the early part of this time window (250–500 ms). Thus, this frontal negative effect seems to be driven by the need to resolve the semantic ambiguity that is sometimes associated with different grammatical uses of a word class ambiguous homograph rather than by the class ambiguity per se.

Semantic memory and verbal working memory correlates of N400 to subordinate homographs

N400 is an event-related brain potential that indexes operations in semantic memory conceptual space, whether elicited by language or some other representation (e.g., drawings). Language models typically propose three stages: lexical access or orthographic- and phonological-level analysis; lexical selection or word-level meaning and associate activation; and lexical integration, sentence- and discourse-level operations. The exact stage that N400 reflects is unknown, although opinion favors lexical integration over lexical selection. Surprisingly, little research has assessed relationships between neuropsychological measures of semantic memory fund of information or verbal working memory capacity and N400. Subjects performed a homograph disambiguation comprehension task with minimal working memory load. Short sentences read: The noun was adjective/verb. The nouns were either homographs or unambiguous. The adjective/verb was disambiguating for the homograph, and congruent or incongruent for the unambiguous noun. The primary noun of interest was the subordinate homograph. Comprehension of the subordinate meaning should correlate with semantic memory stores, reflecting greater knowledge. If N400 primarily reflects lexical access operations, it should also correlate with measures of semantic knowledge. If N400 reflects lexical integration, it should correlate with measures of working memory capacity. Comprehension errors were associated with semantic memory stores, but not working memory capacity. N400 was related to working memory capacity, but not semantic knowledge, suggesting that N400 primarily reflects late-stage working memory operations. N400 to subordinate disambiguating words was larger with greater working memory capacity, and thus may index the absolute capacity of working memory rather than difficulty in contextual integration.

Understanding words in sentence contexts: The time course of ambiguity resolution

Spoken language comprehension requires rapid integration of information from multiple linguistic sources. In the present study we addressed the temporal aspects of this integration process by focusing on the time course of the selection of the appropriate meaning of lexical ambiguities (“ bank”) in sentence contexts. Successful selection of the contextually appropriate meaning of the ambiguous word is dependent upon the rapid binding of the contextual information in the sentence to the appropriate meaning of the ambiguity. We used the N400 to identify the time course of this binding process. The N400 was measured to target words that followed three types of context sentences. In the concordant context, the sentence biased the meaning of the sentence-final ambiguous word so that it was related to the target. In the discordant context, the sentence context biased the meaning so that it was not related to the target. In the unrelated control condition, the sentences ended in an unambiguous noun that was unrelated to the target. Half of the concordant sentences biased the dominant meaning, and the other half biased the subordinate meaning of the sentence-final ambiguous words. The ISI between onset of the target word and offset of the sentence-final word of the context sentence was 100 ms in one version of the experiment, and 1250 ms in the second version. We found that (i) the lexically dominant meaning is always partly activated, independent of context, (ii) initially both dominant and subordinate meaning are (partly) activated, which suggests that contextual and lexical factors both contribute to sentence interpretation without context completely overriding lexical information, and (iii) strong lexical influences remain present for a relatively long period of time.

Effects of Sentential Context on the Processing of Unambiguous Words by the Two Cerebral Hemispheres

The effect of sentence context on the processing of different aspects of meaning of unambiguous nouns by the two cerebral hemispheres was examined. Participants performed a lexical decision task on target words following two primes, an unambiguous noun preceded by an incomplete sentence. Priming sentences were consistent with either the dominant or the subordinate aspect of meaning of their final unambiguous word. Short and long SOAs were used. A principal finding of this study was that, when compared to unrelated aspects of meaning, for both the short and the long SOAs, the dominant and subordinate aspects of meaning of the unambiguous words were activated regardless of context in both hemispheres. However, the activation of the subordinate aspect of meaning of unambiguous words appears to be more sensitive to sentential context, especially when the unambiguous word is being processed by the left hemisphere.

Brain responses to nouns, verbs and class-ambiguous words in context

Recent neuropsychological and imaging data have implicated different brain networks in the processing of different word classes, nouns being linked primarily to posterior, visual object-processing regions and verbs to frontal, motor-processing areas. However, as most of these studies have examined words in isolation, the consequences of such anatomically based representational differences, if any, for the processing of these items in sentences remains unclear. Additionally, in some languages many words (e.g. 'drink') are class-ambiguous, i.e. they can play either role depending on context, and it is not yet known how the brain stores and uses information associated with such lexical items in context. We examined these issues by recording event-related potentials (ERPs) in response to unambiguous nouns (e.g. 'beer'), unambiguous verbs (e. g. 'eat'), class-ambiguous words and pseudowords used as nouns or verbs within two types of minimally contrastive sentence contexts: noun-predicting (e.g. 'John wanted THE [target] but.') and verb-predicting ('John wanted TO [target] but.'). Our results indicate that the nature of neural processing for nouns and verbs is a function of both the type of stimulus and the role it is playing. Even when the context completely specifies their role, word class-ambiguous items differ from unambiguous ones over frontal regions by approximately 150 ms. Moreover, whereas pseudowords elicit larger N400s when used as verbs than when used as nouns, unambiguous nouns and ambiguous words used as nouns elicit more frontocentral negativity than unambiguous verbs and ambiguous words used as verbs, respectively. Additionally, unambiguous verbs elicit a left-lateralized, anterior positivity (approximately 200 ms) not observed for any other stimulus type, though only when these items are used appropriately as verbs (i.e. in verb-predicting contexts). In summary, the pattern of neural activity observed in response to lexical items depends on their general probability of being a verb or a noun and on the particular role they are playing in any given sentence. This implicates more than a simple two-way distinction of the brain networks involved in their storage and processing. Experience, as well as context during on-line language processing, clearly shapes the neural representations of nouns and verbs, such that there is no single neural marker of word class. Our results further suggest that the presence and nature of the word class-based dissociations observed after brain damage are similarly likely to be a function of both the type of stimulus and the context in which it occurs, and thus must be assessed accordingly.

Lexical and message-level sentence context effects on fixation times in reading.

Readers' eye movements were recorded as they read an unambiguous noun in a sentence context. In Experiment 1, fixation durations on a target noun were shorter when it was embedded in context containing a subject noun and a verb that were weakly related to the target than when either content word was replaced with a more neutral word. These results were not affected by changes in the syntactic relations between the content words. In Experiment 2, the semantic relations between the message-level representation of the sentence and the target word were altered whereas the lexical content was held constant. Fixation time on the target word was shorter when the context was semantically related to the target word than when it was unrelated. Intralexical priming effects between the subject noun and the verb were also observed. The results suggest that both lexical and message-level representations can influence the access of an individual lexical item in a sentence context.