Hemispheric Differences in Context Sensitivity During Lexical Ambiguity Resolution

Three experiments were conducted to investigate the influence of contextual constraint on lexical ambiguity resolution in the cerebral hemispheres. A cross-modal priming variant of the divided visual field task was utilized in which subjects heard sentences containing homonyms and made lexical decisions to targets semantically related to dominant and subordinate meanings. Experiment 1 showed priming in both hemispheres of dominant meanings for homonyms embedded in neutral sentence contexts. Experiment 2 showed priming in both hemispheres of dominant and subordinate meanings for homonyms embedded in sentence contexts that biased a central semantic feature of the subordinate meaning. Experiment 3 showed priming of dominant meanings in the left hemisphere (LH), and priming of the subordinate meaning in the right hemisphere (RH) for homonyms embedded in sentences that biased a peripheral semantic feature of the subordinate meaning. These results are consistent with a context-sensitive model of language processing that incorporates differential sensitivity to semantic relationships in the cerebral hemispheres.     

Reading homographs: orthographic, phonologic, and semantic dynamics

Reading processes were compared across 3 word types: homographs (separate pronunciations and meanings, such as lead), homonyms (singular pronunciations but separate meanings, such as spring), and control words (e.g., clock). In Experiment 1, naming reaction times were significantly slower to homographs than to all other words. Experiments 2 and 3 used an association judgment task, with referent words related to the dominant or subordinate meanings of homonyms and homographs. In Experiment 2, homonyms and homographs were presented 1st, followed by disambiguating associates. In Experiment 3, presentation order was reversed. For homographs, performance costs always occurred for subordinate meanings. For homonyms, these costs vanished when context was provided by the preceding associates. The data underscore the priority of phonologic information in word meaning access and suggest that low- and high-level constraints combine to shape word perception.     

Contextual insensitivity in schizophrenic language processing: evidence from lexical ambiguity

The authors investigated whether contextual failures in schizophrenia are due to deficits in the detection of context or the inhibition of contextually irrelevant information. Eighteen schizophrenia patients and 24 nonpsychiatric controls were tested via a cross-modal semantic priming task. Participants heard sentences containing homonyms and made lexical decisions about visual targets related to the homonyms' dominant or subordinate meanings. When sentences moderately biased subordinate meanings (e.g., the animal enclosure meaning of pen), schizophrenia patients showed priming of dominant targets (e.g., paper) and subordinate targets (e.g., pig). In contrast, controls showed priming only of subordinate targets. When contexts strongly biased subordinate meanings, both groups showed priming only of subordinate targets. The results suggest that inhibitory deficits rather than context detection deficits underlie contextual failures in schizophrenia.     

Dynamics of priming-effect for subliminally presented ambiguous pictures

ABSTRACT

The results of this study confirmed that people react differently to preferred meanings of ambiguous images (to those that will get into consciousness later) and to rejected meanings of ambiguous images (those that will not). We observed a facilitative after-effect of the preferred meaning which was expressed in the positive priming-effect, and the following dynamics of the rejected meaning after-effect: positive priming at small values of SOA (30?ms), negative at bigger SOA values (530?ms) and positive priming at all the following SOA values (1,030, 3,030 and 5,030?ms). These results imply that subliminal perception, as well as supraliminal, is selective. We believe that negative priming for one of the meanings of an ambiguous image presented subliminally might be associated with an unconscious decision as to whether or not a particular stimulus will enter into consciousness, in accordance with the negative choice theory.     

Not all ambiguous words are created equal: An EEG investigation of homonymy and polysemy

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.     

汉语同形歧义词歧义消解的两半球差异

实验探讨汉语同形歧义词(homographs)歧义消解的过程及大脑两半球的差异。被试为华中科技大学96名大学生,实验采用词汇判断任务。句子语境呈现在被试的视野中央,探测词在SOA(stimulus onset asynchronism)为100毫秒或400毫秒时呈现在左视野或右视野。结果发现,(1)当SOA为100毫秒时,在左视野(右半球)上,与语境一致的同形歧义词的主要意义得到激活,与语境不一致的次要意义也有一定程度的激活。在右视野(左半球)上,只有与语境一致的同形歧义词的主要意义得到激活。(2)当SOA为400毫秒时,在左、右视野(两半球)上,与语境一致的同形歧义词的主要意义和次要意义都得到激活。结果表明,大脑左半球对汉语歧义词的歧义消解具有一定的优势,语境敏感模型可以较好地解释本实验的结果。     

Hemispheric asymmetries in meaning selection: Evidence from the disambiguation of homophonic vs. heterophonic homographs

Research investigating hemispheric asymmetries in meaning selection using homophonic homographs (e.g., bank), suggests that the left hemisphere (LH) quickly selects contextually relevant meanings, whereas the right hemisphere (RH) maintains a broader spectrum of meanings including those that are contextually irrelevant (e.g., Faust & Chiarello, 1998). The present study investigated cerebral asymmetries in maintaining the multiple meanings of two types of Hebrew homographs: homophonic homographs and heterophonic homographs (e.g., tear). Participants read homographs preceded by a biasing, or a non-biasing sentential context, and performed a lexical decision task on targets presented laterally, 1000 ms after the onset of the sentence-final ambiguous prime. Targets were related to either the dominant or the subordinate meaning of the preceding homograph, or unrelated to it. When targets were presented in the LVF/RH, dominant and subordinate meanings, of both types of homographs, were retained only when they were supported by context. In a non-biasing context, only dominant meanings of homophonic homographs were retained. Alternatively, when targets were presented in the RVF/LH, priming effects for homophonic homographs were only evident when meanings were supported by both context and frequency (i.e., when context favored the dominant meaning). In contrast, heterophonic homographs resulted in activation of dominant meanings, in all contexts, and activation of subordinate meanings, only in subordinate-biasing contexts. The results challenge the view that a broader spectrum of meanings is maintained in the right than in the left hemisphere and suggest that hemispheric differences in the time course of meaning selection (or decay) may be modulated by phonology.     

Hemispheric asymmetries in meaning selection: Evidence from the disambiguation of homophonic vs. heterophonic homographs

Research investigating hemispheric asymmetries in meaning selection using homophonic homographs (e.g., bank), suggests that the left hemisphere (LH) quickly selects contextually relevant meanings, whereas the right hemisphere (RH) maintains a broader spectrum of meanings including those that are contextually irrelevant (e.g., Faust & Chiarello, 1998). The present study investigated cerebral asymmetries in maintaining the multiple meanings of two types of Hebrew homographs: homophonic homographs and heterophonic homographs (e.g., tear). Participants read homographs preceded by a biasing, or a non-biasing sentential context, and performed a lexical decision task on targets presented laterally, 1000 ms after the onset of the sentence-final ambiguous prime. Targets were related to either the dominant or the subordinate meaning of the preceding homograph, or unrelated to it. When targets were presented in the LVF/RH, dominant and subordinate meanings, of both types of homographs, were retained only when they were supported by context. In a non-biasing context, only dominant meanings of homophonic homographs were retained. Alternatively, when targets were presented in the RVF/LH, priming effects for homophonic homographs were only evident when meanings were supported by both context and frequency (i.e., when context favored the dominant meaning). In contrast, heterophonic homographs resulted in activation of dominant meanings, in all contexts, and activation of subordinate meanings, only in subordinate-biasing contexts. The results challenge the view that a broader spectrum of meanings is maintained in the right than in the left hemisphere and suggest that hemispheric differences in the time course of meaning selection (or decay) may be modulated by phonology.     

汉语同形歧义词歧义消解的过程

实验采用启动范式,利用句子语境探讨同形歧义词（homographs）歧义消解的过程。结果表明：与语境一致的歧义词的主要意义首先得到通达,与语境一致的次要意义随后才被激活,与语境不一致的歧义词的意义没有得到激活,语境敏感模型可以较好地解释本实验的结果。     

无意识自我控制目标启动对自我损耗的补偿效应

本研究基于对无意识目标启动的研究,采用阈上、阈下启动方式探讨无意识目标启动对自我损耗的补偿作用。实验1发现,阈上无意识目标启动能够有效提高自我控制,促进自控表现。实验2发现,阈下无意识目标启动对自我损耗存在补偿效应。上述结果提示,通过无意识启动方式激活自我控制目标,可以克服自我损耗的不良效应,且无需意识参与。     

Meaning Selection and the Subcortex: Evidence of Reduced Lexical Ambiguity Repetition Effects Following Subcortical Lesions

Recent research indicates that individuals with nonthalamic subcortical (NS) lesions can experience difficulties processing lexical ambiguities in a variety of contexts. This study examined how prior processing of a lexical ambiguity influences subsequent meaning activation in 10 individuals with NS lesions and 10 matched healthy controls. Subjects made speeded lexical decisions on related or unrelated targets following homophone primes. Homophones were repeated with different targets biasing the same or different meanings on the second presentation. The effects of prime-target relatedness, interstimulus interval (200 or 1250 ms), and same vs. different meaning repetition were examined. Both the patient and control groups showed priming when the same homophone meaning was biased on repetition. When a different meaning was biased on the second presentation, no priming was evident in the controls, while facilitation remained present for the NS group, consistent with aberrant meaning selection and deactivation processes. These findings are discussed in terms of age and task-related repetition effects and current conceptions of frontal–subcortical involvement in cognition.David Copland is supported by the Australian Research Council     

汉语双音节同音词词汇歧义消解过程的研究

使用跨通道词汇判断任务和语义启动技术,两个实验分别考察了孤立状态下和句子语境中汉语双音节同音词意义通达的情况,结果发现(1)在孤立状态下,无论ISI为0毫秒还是-150毫秒,与同音词主要或次要意义有关的探测词都受到了促进;(2)当ISI为0毫秒时,在语境一致的条件下,与同音词主要或次要意义有关的探测词均受到了促进,在语境不一致的条件下,则未发现任何促进效应;(3)当ISI为-150毫秒时,只是在语境一致并且探测词与同音词的主要意义有关的条件下才观察到促进效应。     

Lexical decisions with homophones and homonyms

In two experiments homophones, homonyms, and control words were presented aurally in a lexical decision task. Response times for homophones were significantly faster than those for homonyms and control words, whereas the latter two did not differ. It was concluded that lexical decision times do not provide evidence for multiple entries in the internal lexicon for homonyms. The possibility is considered that the superior performance with homophonic words also does not reflect activation of multiple entries corresponding to multiple meanings, but instead the utilization of orthographic information. This study was supported by a grant from the Natural Sciences and Engineering Research Council of Canada.     

Event-related potentials indicate context effect in reading ambiguous words

The aim of the study was a comparison of lexical and contextual factors in understanding ambiguous words in German. First, a sample of native speakers selected 56 words having maximally strong differences between a dominant and a subordinate meaning. After this, another sample from the same population was visually presented with sentences that activated dominant or subordinate meanings of the words and were accompanied by probes associated with dominant or subordinate meanings. This resulted in a crossed design with two factors: sentence dominant vs. sentence subordinate and probe dominant vs. probe subordinate. An analysis of event-related brain potentials revealed a large, long-lasting and highly-significant N400 wave whenever the meaning of the probe was incongruent with the meaning of the sentence and the lack of this wave whenever the two meanings were congruent. In the typical N400 space and time, the effect was independent of whether the lexical word meaning was dominant or subordinate. At other sites and times, however (e.g., at lateral frontal electrodes F7/F8, and after 700 ms), the congruence effect was significant after dominant sentences only. The data indicate that lexical factors have a rather limited influence on the activation of a particular meaning of ambiguous words. A strong context can virtually override even a very strong difference in the preference for different meanings.     

Strength of Discourse Context as a Determinant of the Subordinate Bias Effect

Two experiments examined the influence of strength of discourse bias on lexical ambiguity resolution. Short passages were constructed to bias polarized ambiguous words (homonyms) strongly or weakly toward the dominant or subordinate meanings. Using a self-paced reading task in Experiment 1, it was demonstrated that in strongly biased discourse, reading times for homonyms in dominant discourse did not differ from those in subordinate discourse. However, when the discourse was weakly biased, homonyms were read faster in dominant discourse than in subordinate discourse. Experiment 2 combined the reading paradigm with a naming task in order to provide an assessment of specific word-meaning activation. Reading times on ambiguous words replicated the results of Experiment 1. In addition, naming latencies for probe words revealed that only the contextually appropriate sense of a homonym was activated in strongly biased discourse. In contrast, both contextually appropriate and inappropriate senses were activated following a weakly biased subordinate discourse, whereas only the dominant sense was activated following weakly biased dominant discourse. The results demonstrate (1) an immediate influence of prior discourse information on lexical processing; and (2) that the strength of discourse constraints can play a governing role in lexical ambiguity resolution. The results were interpreted within the framework of a context-sensitive model of lexical ambiguity resolution.     

Activation of shape and semantic information during ambiguous homophone processing: eye tracking evidence from Hindi

In two visual world eye tracking studies, we examined the activation of subordinate meanings of ambiguous homophones in Hindi and particularly when the sentence context is biased towards the dominant meaning. Participants listened to sentences that were either neutral or biased towards the dominant meaning of the homophone and saw a display containing four pictures. In experiment 1, the display had a shape competitor of the subordinate meaning of the homophone in both neutral and biased conditions along with three unrelated distractors. Experiment 2 had semantic competitors of the subordinate meaning of the homophones along with three distractors. Proportion of fixations to different objects overtime suggested that participants activated the subordinate meanings and oriented their attention to the shape and semantic competitors even when the prior context was biased towards the dominant meaning. Overall, these data from Hindi provide further support to those models of lexical access that assume exhaustive access of both the meanings of an ambiguous homophone. These data suggest even a dominant bias does not eliminate the activation of perceptual and conceptual features of the subordinate meaning.     

维吾尔族与汉族的大学生在汉语歧义词消解中的语境促进效应及反应抑制效应

词汇歧义是语言的普遍现象。在汉语中, 歧义词的种类繁多, 是少数民族学生汉语学习困难的重要原因之一。通过两个实验, 考察在不同加工时间条件下维吾尔族和汉族的大学生在汉语歧义词消解中的语境促进效应及抑制效应。结果发现, 两个民族的大学生均出现了语境促进效应, 但在短时加工条件下, 汉族大学生的语境促进效应显著大于维吾尔族大学生, 在长时加工条件下, 两个民族的大学生的语境促进效应并无显著差异。在短时加工条件下, 仅汉族大学生可以有效地抑制无关信息的干扰; 在长时加工条件下, 两个民族的大学生均可以有效地抑制无关信息的干扰。整个研究表明, 在汉语歧义词消解中, 随着加工时间增加, 维吾尔族大学生的语境促进效应和对无关信息的抑制均可以达到与汉族大学生相近的水平。     

eDom: Norming software and relative meaning frequencies for 544 English homonyms

Words that are homonyms??that is, for which a single written and spoken form is associated with multiple, unrelated interpretations, such as COMPOUND, which can denote an <?enclosure?> or a <?composite?> meaning??are an invaluable class of items for studying word and discourse comprehension. When using homonyms as stimuli, it is critical to control for the relative frequencies of each interpretation, because this variable can drastically alter the empirical effects of homonymy. Currently, the standard method for estimating these frequencies is based on the classification of free associates generated for a homonym, but this approach is both assumption-laden and resource-demanding. Here, we outline an alternative norming methodology based on explicit ratings of the relative meaning frequencies of dictionary definitions. To evaluate this method, we collected and analyzed data in a norming study involving 544 English homonyms, using the eDom norming software that we developed for this purpose. Dictionary definitions were generally sufficient to exhaustively cover word meanings, and the methods converged on stable norms with fewer data and less effort on the part of the experimenter. The predictive validity of the norms was demonstrated in analyses of lexical decision data from the English Lexicon Project (Balota et al., Behavior Research Methods, 39, 445?C459, 2007), and from Armstrong and Plaut (Proceedings of the 33rd Annual Meeting of the Cognitive Science Society, 2223?C2228, 2011). On the basis of these results, our norming method obviates relying on the unsubstantiated assumptions involved in estimating relative meaning frequencies on the basis of classification of free associates. Additional details of the norming procedure, the meaning frequency norms, and the source code, standalone binaries, and user manual for the software are available at http://edom.cnbc.cmu.edu.     

A Time Course View of Sentence Priming Effects

Meaning activation was estimated during (standard naming) and after (delayed naming) target presentation to chart the time course of priming effects during reading comprehension. Using sentences biasing homographs toward their dominant and subordinate meanings, two experiments evaluated context effects across three naming-cue delays: immediate, baseline, baseline+600 ms all at a 0-ms interstimulus interval. When participants named a target immediately as it was presented, results converged with previous findings demonstrating initial context-sensitive meaning activation. The delayed naming conditions revealed little post-access influences for dominant contexts. Subordinate contexts, however, provided the strongest evidence of continued (or sustained) processing. It was concluded that context has immediate and automatic effects on initial meaning activation, after which, strategies are invoked for fine-tuning an interpretation of a sentence and integrating it with new information.     

Confusion and compensation in visual perception: effects of spatiotemporal proximity and selective attention

The authors investigated spatial, temporal, and attentional manipulations in a short-term repetition priming paradigm. Brief primes produced a strong preference to choose the primed alternative, whereas long primes had the opposite effect. However, a 2nd brief presentation of a long prime produced a preference for the primed word despite the long total prime duration. These surprising results are explained by a computational model that posits the offsetting components of source confusion (prime features are confused with target features) and discounting (evidence from primed features is discounted). The authors obtained compelling evidence for these components by showing how they can cooperate or compete through different manipulations of prime salience. The model allows for dissociations between prime salience and the magnitude of priming, thereby providing a unified account of "subliminal" and "supraliminal" priming.