Hemispheric asymmetry in lexical decisions: the effects of grammatical class and imageability

It has been suggested that neural systems for lexical processing of nouns and verbs are anatomically distinct. The aim of the present study was to investigate if brain asymmetry for the processing of these two grammatical classes is also different. Neurologically intact adults performed a lateralized lexical decision task with grammatically unambiguous words of high, medium, and low degrees of imagery. For error scores a right visual field (RVF) advantage and an overall effect of imageability were obtained. For latency scores grammatical class and imageability modified visual field differences: in the noun class a RVF advantage was obtained only for low imagery nouns, while for the verbs the RVF advantage was present for both medium and low imagery verbs. These results suggest that the participation of right hemisphere neural systems in the processing of verbs is more limited than in the processing of nouns.     

Shindigs,brunches, and rodeos: The neural basis of event words

Events (e.g., “running” or “eating”) constitute a basic type within human cognition and human language. We asked whether thinking about events, as compared to other conceptual categories, depends on partially independent neural circuits. Indirect evidence for this hypothesis comes from previous studies showing elevated posterior temporal responses to verbs, which typically label events. Neural responses to verbs could, however, be driven either by their grammatical or by their semantic properties. In the present experiment, we separated the effects of grammatical class (verb vs. noun) and semantic category (event vs. object) by measuring neural responses to event nouns (e.g., “the hurricane”). Participants rated the semantic relatedness of event nouns, as well as of two categories of object nouns—animals (e.g., “the alligator”) and plants (e.g., “the acorn”)—and three categories of verbs—manner of motion (e.g., “to roll”), emission (e.g., “to sparkle”), and perception (e.g., “to gaze”). As has previously been observed, we found larger responses to verbs than to object nouns in the left posterior middle (LMTG) and superior (LSTG) temporal gyri. Crucially, we also found that the LMTG responds more to event than to object nouns. These data suggest that part of the posterior lateral temporal response to verbs is driven by their semantic properties. By contrast, a more superior region, at the junction of the temporal and parietal cortices, responded more to verbs than to all nouns, irrespective of their semantic category. We concluded that the neural mechanisms engaged when thinking about event and object categories are partially dissociable.     

Hemispheric differences in grammatical class.

Although a number of studies have examined lexical asymmetries in hemispheric processing, few have systematically investigated differences between nouns and verbs. Lateralization effects of grammatical class were examined by presenting nouns and verbs of both high and low frequency to either the right or left visual field. Results from both a noun/verb categorization and a lexical decision task revealed a significant visual field by grammatical class interaction. Further analyses revealed that verbs were processed faster in the left compared to the right hemisphere, while there was no hemispheric advantage for the processing of nouns. The present study provides new evidence for the role of grammatical class in lexical processing.     

An image is worth a thousand words: why nouns tend to dominate verbs in early word learning

Nouns are generally easier to learn than verbs (e.g., Bornstein, 2005; Bornstein et al., 2004; Gentner, 1982; Maguire, Hirsh-Pasek, & Golinkoff, 2006). Yet, verbs appear in children's earliest vocabularies, creating a seeming paradox. This paper examines one hypothesis about the difference between noun and verb acquisition. Perhaps the advantage nouns have is not a function of grammatical form class but rather related to a word's imageability. Here, word imageability ratings and form class (nouns and verbs) were correlated with age of acquisition according to the MacArthur-Bates Communicative Development Inventory (CDI) (Fenson et al., 1994). CDI age of acquisition was negatively correlated with words' imageability ratings. Further, a word's imageability contributes to the variance of the word's age of acquisition above and beyond form class, suggesting that at the beginning of word learning, imageability might be a driving factor.     

动词论元结构复杂性加工的认知神经机制

动词论元结构复杂性表现在论元数量、论元范畴选择模式、题元角色指派模式和映射方式四个方面。大部分实证研究表明, 更多的论元数量、选择性论元范畴、选择性题元角色指派以及非典型映射, 使动词论元结构加工的认知神经机制更复杂。多论元加工功能脑区主要涉及左侧额下回和外侧裂周后部; 选择性论元范畴加工功能脑区主要涉及左侧额下回、额叶中后部、颞上回和颞叶中后部; 选择性题元角色指派加工功能脑区主要涉及外侧裂周后部、左侧额叶中后部和额下回; 非典型映射加工功能脑区主要涉及左侧额下回、颞上回、颞中回和颞叶后部。左侧额下回可能涉及初始句法加工、动词次范畴确定、句法移位和非宾格动词语义加工, 左侧额叶中后部可能涉及初始句法加工和动词次范畴确定, 左侧颞上回和颞叶中后部可能涉及表层句法加工和表层论元句法-语义整合, 外侧裂周后部可能涉及论元语义表征。动词论元结构加工过程和动词词汇特征表明, 复杂性某些方面存在交互作用。动词论元结构复杂性与加工难易的对应关系、复杂性加工难度层级和交互作用的认知神经机制以及汉语动词论元结构复杂性加工认知神经机制等议题, 有待进一步探讨。     

Imageability and distributional typicality measures of nouns and verbs in contemporary English

Dissociations between noun and verb processing are not uncommon after brain injury; yet, precise psycholinguistic comparisons of nouns and verbs are hampered by the underrepresentation of verbs in published semantic word norms and by the absence of contemporary estimates for part-of-speech usage. We report herein imageability ratings and rating response times (RTs) for 1,197 words previously categorized as pure nouns, pure verbs, or words of balanced noun-verb usage on the basis of the Francis and Ku?era (1982) norms. Nouns and verbs differed in rated imageability, and there was a stronger correspondence between imageability rating and RT for nouns than for verbs. For all word types, the image-rating-RT function implied that subjects employed an image generation process to assign ratings. We also report a new measure of noun-verbtypicality that used the Hyperspace Analog to Language (HAL; Lund & Burgess, 1996) context vectors (derived from a large sample of Usenet text) to compute the mean context distance between each word and all of thepure nouns andpure verbs. For a subset of the items, the resulting HAL noun-verb difference score was compared with part-of-speech usage in a representative sample of the Usenet corpus. It is concluded that this score can be used to estimate the extent to which a given word occurs in typical noun or verb sentence contexts in informal contemporary English discourse. The item statistics given in Appendix B will enable experimenters to select representative examples of nouns and verbs or to compare typical with atypical nouns (or verbs), while holding constant or covarying rated imageability.     

Sometimes a noun is just a noun: comments on Bird, Howard, and Franklin (2000)

Bird, Howard, and Franklin (2000) have proposed a semantic-conceptual explanation of grammatical category-specific deficits that attributes impairments in noun and verb processing to two distinct mechanisms. According to their account, apparent deficits in verb production are not category specific, but rather result from the lower imageability of verbs compared to concrete nouns. Noun deficits are said to result from differences in the distribution of semantic feature types such that damage to sensory features results in disproportionate impairments in naming nouns, especially animate nouns, compared to verbs. However, this hypothesis, which we call the "extended sensory/functional theory" (ESFT), fails on several counts. First, the assumption that representations of living things are more heavily freighted with sensory features than are those of nonliving objects does not have any reliable empirical basis. Second, the ESFT incorrectly predicts associations between deficits in processing sensory features and living things or functional features and nonliving things. Finally, there are numerous cases of patients with grammatical category-specific deficits that do not seem to be consistent with damage at the semantic level. All of this suggests that the ESFT is not a useful model for considering grammatical (or semantic) category-specific deficits.     

Age of acquisition and imageability ratings for a large set of words, including verbs and function words

Age of acquisition and imageability ratings were collected for 2,645 words, including 892 verbs and 213 function words. Words that were ambiguous as to grammatical category were disambiguated: Verbs were shown in their infinitival form, and nouns (where appropriate) were preceded by the indefinite article (such asto crack anda crack). Subjects were speakers of British English selected from a wide age range, so that differences in the responses across age groups could be compared. Within the subset of early acquired noun/verb homonyms, the verb forms were rated as later acquired than the nouns, and the verb homonyms of high-image ability nouns were rated as significantly less imageable than their noun counterparts. A small number of words received significantly earlier or later age of acquisition ratings when the 20–40 years and 50–80 years age groups were compared. These tend to comprise words that have come to be used more frequently in recent years (either through technological advances or social change), or those that have fallen out of common usage. Regression analyses showed that although word length, familiarity, and concreteness make independent contributions to the age of acquisition measure, frequency and imageability are the most important predictors of rated age of acquisition.     

Noun Imageability Facilitates the Acquisition of Plurals: Survival Analysis of Plural Emergence in Children

Some research in child language suggests that semantically general verbs appear in grammatical structures earlier than semantically complex, specific ones. The present study examines whether this was the case in nouns, using imageability as a proxy measure of semantic generality. Longitudinal corpus data from 12 children from the Manchester corpus in CHILDES were used to obtain information on the first occurrence of plurals. A total of 3,560 uninflected nouns were identified in the corpora, of which 1,202 were observed in the plural. Survival analyses indicated that the chance of observing a plural form increases with the imageability rating of the noun, even after accounting for the age of acquisition of the uninflected noun, maternal input frequency, and word length. Noun imageability thus facilitates the acquisition of plural forms. This finding contradicts the observations from verbs, and indicates that the acquisition of grammar is facilitated by high imageability rather than semantic generality.     

Why is a verb like an inanimate object? Grammatical category and semantic category deficits

Semantic category effects, such as difficulties in naming animate things relative to inanimate objects, have been explained in terms of the relative weightings of perceptual and functional features within the semantic representations of these concepts. We argue that grammatical category deficits, such as difficulties in naming nouns relative to verbs, can be explained within the same framework. We hypothesize that verb concepts are richer in functional than sensory features and present a model of the semantic representations of animate nouns, inanimate nouns, and verbs. The model demonstrates that sensory feature damage results in a deficit for naming living things but spares verb naming, and functional feature damage results in a deficit for naming inanimate objects and verbs. We then report the assessment results of two patient groups. In accordance with the model's predictions, the "verb spared" patients were consistently worse at naming living things than inanimate objects, and their definitions of both living and nonliving items were lacking in sensory information. We conclude that damage to sensory features in semantic representations causes difficulties in naming concrete nouns relative to action verbs, and within the grammatical category of nouns, animate items will be more severely affected. Imageability was shown to be a strong predictor of naming performance in the "verb deficit" patients, and when this variable was controlled no class effect remained. Production of definitions revealed no differential damage to sensory or functional features, and no consistent effect of animacy in naming was shown. While the model suggests that verb deficits might occur in patients for whom functional features are damaged relative to sensory features, we conclude that the "verb deficit" shown in our patients (and potentially in many previously reported cases) was an artifact of the lower imageability of verbs in confrontation naming tasks.     

Verb-noun double dissociation in aphasic lexical impairments: the role of word frequency and imageability

Neurolinguistic studies have provided important evidence regarding the organization of lexical representations and the structure of underlying conceptual knowledge; in particular, it has been shown that the retrieval of verbs and nouns can be damaged selectively. Dissociated lexical damage is proof of an independent mental organization of lexical representations and/or of the underlying processes. The aim of the present study is to estimate the rate of dissociated impairments for nouns and verbs on a large sample of mild to moderate aphasic patients and to investigate the mechanisms underlying such phenomena. In addition, the authors wished to verify to what degree the impairment for nouns and verbs is related to a specific type of language disorder. A confrontation naming task for verbs and nouns was administered to 58 aphasic patients. The major lexical (word frequency and age of acquisition) and semantic variables (familiarity and imageability of the underlying concept) were considered for each noun and verb used in the task. Verbs were distinguished by major functional classes (transitive, intransitive, and ergative verbs). The data collected from this task were analyzed twice: (i) as a group study comparison of major aphasic subgroups and (ii) as a multiple single case study to evaluate the differences on the naming of verbs and nouns and the effect of the lexical semantic variables on each individual patient. The results confirm the existence of dissociated naming impairments of verbs and nouns. Selective impairment of verbs is more frequent (34%) than that of nouns (10%). In many cases, the dissociated pattern of naming impairment disappeared when the effect of the concomitant variables (word frequency and imageability) was removed, but in approximately one-fifth of the cases the noun or verb superiority was preserved. Noun superiority emerged in five of six agrammatic patients. Both the naming of verbs (n = 9) or of nouns (n = 6) could be impaired selectively in fluent aphasic patients. The results lend support to the hypothesis of an independent mental organization of nouns and verbs, but a substantial effect of imageability and word frequency suggests an interaction of the naming impairment with underlying lexical and semantic aspects.     

The role of grammatical class on word recognition

The double dissociation between noun and verb processing, well documented in the neuropsychological literature, has not been supported in imaging studies. Recent imaging studies, in fact, suggest that once confounding with semantics is eliminated, grammatical class effects only emerge as a consequence of building frames. Here we assess this hypothesis behaviorally in two visual word recognition experiments. In Experiment 1, participants made lexical decisions on verb targets. We manipulated the grammatical class of the prime words (either nouns or verbs and always introduced in a minimal phrasal context, i.e., “the + N” or “to + V”), and their semantic similarity to a target (related vs. unrelated). We found reliable effects of grammatical class, and no interaction with semantic similarity. Experiment 2 further explored this grammatical class effect, using verb targets preceded by semantically unrelated verb vs. noun primes. In one condition, prime words were presented as bare words; in the other, they were presented in the minimal phrasal context used in Experiment 1. Grammatical class effects only arose in the latter but not in the former condition thus providing evidence that word recognition does not recruit grammatical class information unless it is provided to the system.     

Semantic context influences memory for verbs more than memory for nouns

Three experiments revealed that memory for verbs is more dependent on semantic context than is memory for nouns. The participants in Experiment 1 were asked to remember either nouns or verbs from intransitive sentences. A recognition test included verbatim sentences, sentences with an old noun and a new verb, sentences with an old verb and a new noun, and entirely new sentences. Memory for verbs was significantly better when the verb was presented with the same noun at encoding and at retrieval. This contextual effect was much smaller for nouns. Experiments 2 and 3 replicated this effect and provided evidence that context effects reflect facilitation from bringing to mind the same meaning of a verb at encoding and at retrieval. Memory for verbs may be more dependent on semantic context because the meanings of verbs are more variable across semantic contexts than are the meanings of nouns.     

Nouns and Verbs: A Comparison of Definitional Style

The present investigation is a study of the definitional style of nouns and verbs in typically developing school-age children. A total of 30 children in upper-elementary grades provided verbal definitions for 10 common high-frequency nouns (e.g., apple, boat, baby) and 10 common high-frequency verbs (e.g., climb, sing, throw). All definitions were coded and scored for semantic content (meaning) and grammatical form (syntax). Results revealed no significant difference between noun and verb definitions for content scores. For form, however, noun definition scores were significantly higher than verb definition scores. A supplementary analysis was conducted to explore development of noun and verb definitions in upper-elementary grades. Input factors, word frequency, as well as theory of the organization of the mental lexicon are discussed in relation to definitional skill.     

动、名词词类特异性损伤的研究现状

词汇的各类知识信息（如,语法信息）在人脑中的表征和加工方式是当前学者们研究的热点之一,以患者为研究对象已成为了其中一种重要的研究手段。期间,人们发现脑损伤使得一些患者对动词或名词表现出选择性认知加工障碍,即出现了动、名词词类特异性损伤。通过探讨这一现象发生的机理,将为揭示词类的语法信息在人脑中的表征和加工方式提供了契机。文章介绍了这一现象的表现形式,即一些脑损伤患者对有关动词的知识比有关名词的知识丧失得更严重,而有些患者的损伤模式却与其恰好相反。另外,文中也阐述了对该现象的3种理论解释：语法解释、语义－概念解释和词典解释。     

Effect of Representational Distance Between Meanings on Recognition of Ambiguous Spoken Words

Previous research indicates that mental representations of word meanings are distributed along both semantic and syntactic dimensions such that nouns and verbs are relatively distinct from one another. Two experiments examined the effect of representational distance between meanings on recognition of ambiguous spoken words by comparing recognition of unambiguous words, noun–verb homonyms, and noun–noun homonyms. In Experiment 1, auditory lexical decision was fastest for unambiguous words, slower for noun–verb homonyms, and slowest for noun–noun homonyms. In Experiment 2, response times for matching spoken words to pictures followed the same pattern and eye fixation time courses revealed converging, gradual time course differences between conditions. These results indicate greater competition between meanings of ambiguous words when the meanings are from the same grammatical class (noun–noun homonyms) than when they are from different grammatical classes (noun–verb homonyms).     

The neural reality of syntactic transformations: evidence from functional magnetic resonance imaging

The functional anatomy of syntactic transformations, a major computational operation invoked in sentence processing, was identified through a functional magnetic resonance imaging investigation. A grammaticality judgment task was used, presented through a novel hidden-blocks design. Subjects listened to transformational and nontransformational sentences in which a host of other complexity generators (number of words, prepositions, embeddings, etc.) were kept constant. A series of analyses revealed that the neural processing of transformations is localizable, evoking a highly lateralized and localized activation in the left inferior frontal gyrus (Broca's region) and bilateral activation in the posterior superior temporal sulcus. The pattern of activation associated with transformational analysis was distinct from the one observed in neighboring regions, and anatomically separable from the effects of verb complexity, which yielded significant activation in the left posterior superior temporal sulcus. Taken together with neuropsychological evidence, these results uncover the neural reality of syntactic transformations.     

Dissociation and association of the embodied representation of tool-use verbs and hand verbs: An fMRI study

Embodied semantic theories suppose that representation of word meaning and actual sensory-motor processing are implemented in overlapping systems. According to this view, association and dissociation of different word meaning should correspond to dissociation and association of the described sensory-motor processing. Previous studies demonstrate that although tool-use actions and hand actions have overlapping neural substrates, tool-use actions show greater activations in frontal–parietal–temporal regions that are responsible for motor control and tool knowledge processing. In the present study, we examined the association and the dissociation of the semantic representation of tool-use verbs and hand action verbs. Chinese verbs describing tool-use or hand actions without tools were included, and a passive reading task was employed. All verb conditions showed common activations in areas of left middle frontal gyrus, left inferior frontal gyrus (BA 44/45) and left inferior parietal lobule relative to rest, and all conditions showed significant effects in premotor areas within the mask of hand motion effects. Contrasts between tool-use verbs and hand verbs demonstrated that tool verbs elicited stronger activity in left superior parietal lobule, left middle frontal gyrus and left posterior middle temporal gyrus. Additionally, psychophysiological interaction analyses demonstrated that tool verbs indicated greater connectivity among these regions. These results suggest that the brain regions involved in tool-use action processing also play more important roles in tool-use verb processing and that similar systems may be responsible for word meaning representation and actual sensory-motor processing.     

Selection demands versus association strength in the verb generation task

Neuroimaging and neuropsychological data from Thompson-Schill and colleagues (Thompson-Schill, D’Esposito, Aguirre, & Farah, 1997; Thompson-Schill et al., 1998) showed that in the verb generation task, the left inferior frontal gyrus (left IFG) was more involved in a high-selection condition, in which the noun had two verb responses of equal association strength, than in a low-selection condition, in which the noun had only one strongly associated verb. They proposed that the left IFG was involved in selecting semantic information from competing alternatives. The present study compared verb generation in two high-selection conditions that varied in the association strength of the most frequently produced verbs. The results from neurally intact participants and a patient with a lesion that included the left IFG indicated that association strength between nouns and the most frequently produced verb, rather than competition during verb selection, affected verb generation. The degree of involvement of the left IFG may depend on the difficulty of verb retrieval as reflected in association strength.     

A Connectionist Model of English Past Tense and Plural Morphology

The acquisition of English noun and verb morphology is modeled using a single-system connectionist network. The network is trained to produce the plurals and past tense forms of a large corpus of monosyllabic English nouns and verbs. The developmental trajectory of network performance is analyzed in detail and is shown to mimic a number of important features of the acquisition of English noun and verb morphology in young children. These include an initial error-free period of performance on both nouns and verbs followed by a period of intermittent over-regularization of irregular nouns and verbs. Errors in the model show evidence of phonological conditioning and frequency effects. Furthermore, the network demonstrates a strong tendency to regularize denominal verbs and deverbal nouns and masters the principles of voicing assimilation. Despite their incorporation into a single-system network, nouns and verbs exhibit some important differences in their profiles of acquisition. Most importantly, noun inflections are acquired earlier than verb inflections. The simulations generate several empirical predictions that can be used to evaluate further the suitability of this type of cognitive architecture in the domain of inflectional morphology.