Understanding of action-related and abstract verbs in comparison: a behavioral and TMS study

Does the comprehension of both action-related and abstract verbs rely on motor simulation? In a behavioral experiment, in which a semantic task was used, response times to hand-action-related verbs were briefer than those to abstract verbs and both decreased with repetition of presentation. In a transcranial magnetic stimulation (TMS) experiment, single-pulse stimulation was randomly delivered over hand motor area of the left primary motor cortex to measure cortical-spinal excitability at 300 or 500 ms after verb presentation. Two blocks of trials were run. In each block, the same verbs were randomly presented. In the first block, stimulation induced an increase in motor evoked potentials only when TMS was applied 300 ms after action-related verb presentation. In the second block, no modulation of motor cortex was found according to type of verb and stimulation-delay. These results confirm that motor simulation can be used to understand action rather than abstract verbs. Moreover, they suggest that with repetition, the semantic processing for action verbs does not require activation of primary motor cortex anymore.     

Body part representations in verbal semantics

Embodied theories of language propose that word meaning is inextricably tied to—grounded in—mental representations of perceptual, motor, and affective experiences of the world. The four experiments described in this article demonstrate that accessing the meanings of action verbs like smile, punch, and kick requires language understanders to activate modality-specific cognitive representations responsible for performing and perceiving those same actions. The main task used is a word-image matching task, where participants see an action verb and an image depicting an action. Their task is to decide as quickly as possible whether the verb and the image depict the same action. Of critical interest is participants’ behavior when the verb and image do not match, in which case the two actions can use the same effector or different effectors. In Experiment 1, we found that participants took significantly longer to reject a verb-image pair when the actions depicted by the image and denoted by the verb used the same effector than when they used different effectors. Experiment 2 yielded the same result when the order of presentation was reversed, replicating the effect in Cantonese. Experiment 3 replicated the effect in English with a verb-verb near-synonym task, and in Experiment 4, we once again replicated the effect with learners of English as a second language. This robust interference effect, whereby a shared effector slows discrimination, shows that language understanders activate effector-specific neurocognitive representations during both picture perception and action word understanding.     

What matters is the underlying experience: Similar motor responses during processing observed hand actions and hand-related verbs

It is well-accepted that processing observed actions involves at some extent the same neural mechanisms responsible for action execution. More recently, it has been forwarded that also the processing of verbs expressing a specific motor content is subserved by the neural mechanisms allowing individuals to perform the content expressed by that linguistic material. This view is also known as embodiment and contrasts with a more classical approach to language processing that considers it as amodal. In the present study, we used a go/no-go paradigm, in which participants were requested to respond to real words and pictures and refrain from responding when presented stimuli were pseudowords and scrambled images. Real stimuli included pictures depicting hand- and foot-related actions and verbs expressing hand- and foot-related actions. We, therefore, directly compared the modulation of hand motor responses during the observation of actions and the presentation of verbs, expressing actions in the same category. The results have shown that participants gave slower hand motor responses during the observation of hand actions and the processing of hand-related verbs as than observed foot actions and related verbs. These findings support embodiment showing that whatever the modality of presentation (observed action or verb), the modulation of hand motor responses was similar, thus suggesting that processing seen actions and related verbs shares common mechanisms most likely involving the motor system and the underlying motor experience.     

The comprehension of action-related sentences may cause interference rather than facilitation on matching actions

This study used a dual-task paradigm to analyze the time course of motor resonance during the comprehension of action language. In the study, participants read sentences describing a transfer either away from (“I threw the tennis ball to my rival”) or toward themselves (“My rival threw me the tennis ball”). When the transfer verb appeared on the screen, and after a variable stimulus onset asynchrony (SOA), a visual motion cue (Experiment 1) or a static cue (Experiment 2) prompted participants to move their hand either away from or toward themselves to press a button. The results showed meaning–action interference at short SOAs and facilitation at the longest SOA for the matching conditions. These results support the hypothesis that motor processes associated with the comprehension of action-related language interfere with an overlapping motor task, whereas they facilitate a delayed motor task. These effects are discussed in terms of resonance processes in the motor cortex.     

Imageability and semantic association in the representation and processing of event verbs

This study examined the relative salience of imageability (the degree to which a word evokes mental imagery) versus semantic association (the density of semantic network in which a word is embedded) in the representation and processing of four types of event verbs: sensory, cognitive, speech, and motor verbs. ERP responses were recorded, while 34 university students performed on a lexical decision task. Analysis focused primarily on amplitude differences across verb conditions within the N400 time window where activities are considered representing meaning activation. Variation in N400 amplitude across four types of verbs was found significantly associated with the level of imageability, but not the level of semantic association. The findings suggest imageability as a more salient factor relative to semantic association in the processing of these verbs. The role of semantic association and the representation of speech verbs are also discussed.     

Acquiring and processing verb argument structure: distributional learning in a miniature language

Adult knowledge of a language involves correctly balancing lexically-based and more language-general patterns. For example, verb argument structures may sometimes readily generalize to new verbs, yet with particular verbs may resist generalization. From the perspective of acquisition, this creates significant learnability problems, with some researchers claiming a crucial role for verb semantics in the determination of when generalization may and may not occur. Similarly, there has been debate regarding how verb-specific and more generalized constraints interact in sentence processing and on the role of semantics in this process. The current work explores these issues using artificial language learning. In three experiments using languages without semantic cues to verb distribution, we demonstrate that learners can acquire both verb-specific and verb-general patterns, based on distributional information in the linguistic input regarding each of the verbs as well as across the language as a whole. As with natural languages, these factors are shown to affect production, judgments and real-time processing. We demonstrate that learners apply a rational procedure in determining their usage of these different input statistics and conclude by suggesting that a Bayesian perspective on statistical learning may be an appropriate framework for capturing our findings.     

A neuroconstructivist model of past tense development and processing

We present a neural network model of learning and processing the English past tense that is based on the notion that experience-dependent cortical development is a core aspect of cognitive development. During learning the model adds and removes units and connections to develop a task-specific final architecture. The model provides an integrated account of characteristic errors during learning the past tense, adult generalization to pseudoverbs, and dissociations between verbs observed after brain damage in aphasic patients. We put forward a theory of verb inflection in which a functional processing architecture develops through interactions between experience-dependent brain development and the structure of the environment, in this case, the statistical properties of verbs in the language. The outcome of this process is a structured processing system giving rise to graded dissociations between verbs that are easy and verbs that are hard to learn and process. In contrast to dual-mechanism accounts of inflection, we argue that describing dissociations as a dichotomy between regular and irregular verbs is a post hoc abstraction and is not linked to underlying processing mechanisms. We extend current single-mechanism accounts of inflection by highlighting the role of structural adaptation in development and in the formation of the adult processing system. In contrast to some single-mechanism accounts, we argue that the link between irregular inflection and verb semantics is not causal and that existing data can be explained on the basis of phonological representations alone. This work highlights the benefit of taking brain development seriously in theories of cognitive development.     

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.     

Differences in Noun and Verb Processing in Lexical Decision Cannot be Attributed to Word Form and Morphological Complexity Alone

It has been suggested that the effect of word category in noun and verb processing reflects typical word class properties, which can be characterized in terms of semantic as well as syntactic and morphological features. The present study is aimed at differentiating and discussing the relative contribution of these aspects with a main focus on syntactic and morphological processing. Experiment 1 established a processing advantage for nouns in German visual lexical decision, using nouns denoting biological and man-made objects as compared to transitive and intransitive verbs. Experiment 2 showed that the noun advantage persisted even when the morphological differences between word categories were reduced by using identical suffixes in nouns and verbs. Overall results suggest that the processing differences cannot be reduced to variables such as frequency, word form, or morphological complexity. Reaction time differences between transitive and intransitive verbs strengthen the role of syntactic information. In line with previous accounts the observed effects are discussed in terms of a category-specific combination of linguistic parameters.     

Repetition priming within and between languages in verb generation: evidence for shared verb concepts

Although translation equivalents for concrete nouns are known to have shared core conceptual representations in bilingual memory (Francis, 1999), the status of translation-equivalent verbs has not been systematically tested. Three repetition-priming experiments using a verb generation task were used to determine whether verbs have shared representations across languages and to identify the processes facilitated in repeated verb generation. In Experiment 1 fluent Spanish-English bilingual speakers exhibited repetition priming both within and between languages, but between-language priming was weaker. In Experiment 2 performance of non-bilingual English and Spanish speakers was equivalent to that of bilingual speakers responding in their dominant language. Experiment 3 used manipulations meant to isolate noun comprehension, verb concept selection, and verb production. The between-language priming in Experiments 1 and 3 indicates that verb concepts are shared across languages and that verb concept selection exhibits facilitation. Experiment 3 showed that the greater within-language priming was due primarily to facilitation of verb production processes.     

Repetition priming within and between languages in verb generation: Evidence for shared verb concepts

Although translation equivalents for concrete nouns are known to have shared core conceptual representations in bilingual memory (Francis, 1999), the status of translation-equivalent verbs has not been systematically tested. Three repetition-priming experiments using a verb generation task were used to determine whether verbs have shared representations across languages and to identify the processes facilitated in repeated verb generation. In Experiment 1 fluent Spanish–English bilingual speakers exhibited repetition priming both within and between languages, but between-language priming was weaker. In Experiment 2 performance of non-bilingual English and Spanish speakers was equivalent to that of bilingual speakers responding in their dominant language. Experiment 3 used manipulations meant to isolate noun comprehension, verb concept selection, and verb production. The between-language priming in Experiments 1 and 3 indicates that verb concepts are shared across languages and that verb concept selection exhibits facilitation. Experiment 3 showed that the greater within-language priming was due primarily to facilitation of verb production processes.     

Effects of verb complexity on speech errors

Two experiments examined whether semantically related verbs that contrast with respect to the absence versus the presence of an additional semantic feature differentially compete for selection during the encoding of a sentence for production. In both experiments, a speech error induction task was used to elicit contextual (misordering) errors involving semantically related verbs that contrasted only in their semantic complexity or in both their semantic and morphophonological complexity. The prediction was that an asymmetry in contextual errors would be observed in which the more complex verbs would replace the simpler verbs more often than the reverse. This prediction was confirmed in both experiments, with more perseverations and anticipations involving the semantically more complex verb of antonym pairs in Experiment 1, and more perseverations and anticipations involving the semantically more-specified verb of a heavy-light pair in Experiment 2. The implications of the results for spreading-activation theories of language production are discussed.     

Auditory verb perception recruits motor systems in the developing brain: an fMRI investigation

This study investigated neural activation patterns during verb processing in children, using fMRI (functional Magnetic Resonance Imaging). Preschool children (aged 4–6) passively listened to lists of verbs and adjectives while neural activation was measured. Findings indicated that verbs were processed differently than adjectives, as the verbs recruited motor systems in the frontal cortex during auditory perception, but the adjectives did not. Further evidence suggested that different types of verbs activated different regions in the motor cortex. The results demonstrate that the motor system is recruited during verb perception in the developing brain, reflecting the embodied nature of language learning and processing.     

How toddlers begin to learn verbs

Any theory of language must account for how children learn verbs, the gateway to grammar. Yet verbs can be difficult to learn. Building on Gentner's 'natural partitions hypothesis' we suggest that, to learn a verb, infants must conceptualize components of events and map verbs in the ambient language onto those components. Although toddlers detect and categorize at least some of the conceptual underpinnings of verb categories, the mapping of verbs onto these representations is not transparent. Mapping is a difficult problem in its own right. The Emergentist Coalition Model that has been used to explain noun learning also begins to explain how children move from perceptual to social and then to linguistic information to link verbs to actions and events.     

Walking or talking? Behavioral and neurophysiological correlates of action verb processing

Brain activity elicited by visually presented words was investigated using behavioral measures and current source densities calculated from high-resolution EEG recordings. Verbs referring to actions usually performed with different body parts were compared. Behavioral data indicated faster processing of verbs referring to actions performed with the face muscles and articulators (face-related words) compared to verbs referring to movements involving the lower half of the body (leg-related words). Significant topographical differences in brain activity elicited by verb types were found starting approximately 250 ms after word onset. Differences were seen at recording sites located over the motor strip and adjacent frontal cortex. At the vertex, close to the cortical representation of the leg, leg-related verbs (for example, to walk) produced strongest in-going currents, whereas for face-related verbs (for example, to talk) the most in-going activity was seen at more lateral electrodes placed over the left Sylvian fissure, close to the representation of the articulators. Thus, action words caused differential activation along the motor strip, with strongest in-going activity occurring close to the cortical representation of the body parts primarily used for carrying out the actions the verbs refer to. Topographically specific physiological signs of word processing started earlier for face-related words and lasted longer for verbs referring to leg movements. We conclude that verb types can differ in their processing speed and can elicit neurophysiological activity with different cortical topographies. These behavioral and physiological differences can be related to cognitive processes, in particular to lexical semantic access. Our results are consistent with associative theories postulating that words are organized in the brain as distributed cell assemblies whose cortical distributions reflect the words' meanings.     

Embodied grounding of memory: Toward the effects of motor execution on memory consolidation

Behavioural and neuroscientific research has provided evidence for a strong functional link between the neural motor system and lexical–semantic processing of action-related language. It remains unclear, however, whether the impact of motor actions is restricted to online language comprehension or whether sensorimotor codes are also important in the formation and consolidation of persisting memory representations of the word's referents. The current study now demonstrates that recognition performance for action words is modulated by motor actions performed during the retention interval. Specifically, participants were required to learn words denoting objects that were associated with either a pressing or a twisting action (e.g., piano, screwdriver) and words that were not associated to actions. During a 6–8-minute retention phase, participants performed an intervening task that required the execution of pressing or twisting responses. A subsequent recognition task revealed a better memory for words that denoted objects for which the functional use was congruent with the action performed during the retention interval (e.g., pepper mill–twisting action, doorbell–pressing action) than for words that denoted objects for which the functional use was incongruent. In further experiments, we were able to generalize this effect of selective memory enhancement of words by performing congruent motor actions to an implicit perceptual (Experiment 2) and implicit semantic memory test (Experiment 3). Our findings suggest that a reactivation of motor codes affects the process of memory consolidation and emphasizes therefore the important role of sensorimotor codes in establishing enduring semantic representations.     

动词理解中空间表征的激活过程

探讨动词理解中空间表征的激活过程。被试听以不同空间轴向动词作谓语的句子后辨认视觉刺激的形状。实验1以肯定句为材料探讨语义理解对视知觉任务的影响。实验2以客观原因否定句为材料排除句子表征的影响。实验3以主观原因否定句为材料探讨动词空间元素的激活机制。总的结果表明,动词理解过程中激活其表征中的空间元素,这种激活是自动的、非策略性的,不受情境中客观原因或主观意愿否定的影响。动词理解空间效应反映了语言表征中的知觉运动特征     

Parkinson’s disease disrupts both automatic and controlled processing of action verbs

The problem of how word meaning is processed in the brain has been a topic of intense investigation in cognitive neuroscience. While considerable correlational evidence exists for the involvement of sensory-motor systems in conceptual processing, it is still unclear whether they play a causal role. We investigated this issue by comparing the performance of patients with Parkinson’s disease (PD) with that of age-matched controls when processing action and abstract verbs. To examine the effects of task demands, we used tasks in which semantic demands were either implicit (lexical decision and priming) or explicit (semantic similarity judgment). In both tasks, PD patients’ performance was selectively impaired for action verbs (relative to controls), indicating that the motor system plays a more central role in the processing of action verbs than in the processing of abstract verbs. These results argue for a causal role of sensory-motor systems in semantic processing.     

How the motor system handles nouns: a behavioral study

It is an open question whether the motor system is involved during understanding of concrete nouns, as it is for concrete verbs. To clarify this issue, we carried out a behavioral experiment using a go-no go paradigm with an early and delayed go-signal delivery. Italian nouns referring to concrete objects (hand-related or foot-related) and abstract entities served as stimuli. Right-handed participants read the stimuli and responded when the presented word was concrete using the left or right hand. At the early go-signal, slower right-hand responses were found for hand-related nouns compared to foot-related nouns. The opposite pattern was found for the left hand. These findings demonstrate an early lateralized modulation of the motor system during noun processing, most likely crucial for noun comprehension.