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.     

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。     

无语境条件下汉语词类歧义词的意义激活

以单字词为实验材料,采用启动命名任务,在孤立词条件下考察了汉语词类歧义词不同意义激活的时间进程特点。实验发现,歧义词的两种意义都能被激活,但主要意义激活得较早,次要意义激活速度较慢;当两种意义都激活之后,次要意义的激活水平降低,而主要意义仍维持在一定激活水平。结果表明,汉语词类歧义词的多重激活过程会受到意义相对频率的影响。     

LIFG-based attentional control and the resolution of lexical ambiguities in sentence context

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

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.     

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.     

汉语歧义句的加工

通过两个实验,对汉语歧义句多种解释的意义频率和语境位置在句子歧义解析过程中的效应进行了考察。实验结果表明：（１）前语境为被试提供了某种预期信息,它对句子歧义解析的效应大于后语境;（２）在句子歧义解析过程中,不管有语境或无语境,不管是前语境或后语境,被试提取歧义句的主要意思比提取次要意思快;（３）歧义句的多种解释的激活,有一个时间进程,在短延迟间隔条件下,歧义句的主要意思可以被激活并形成表征,但次要意思的激活和表征则需要较长的时间     

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.     

Global context effects on processing lexically ambiguous words: Evidence from eye fixations

Readers' eye movements were monitored as they read biased ambiguous target words in the context of a short paragraph. Two aspects of context were manipulated. The global context was presented in the topic sentence of the paragraph and instantiated either the dominant or the subordinate meaning of biased ambiguous target words (those with highly dominant meanings). Local contextual information either preceded or followed the target word and was always consistent with the subordinate interpretation. Consistent with prior research, we obtained a subordinate bias effect wherein readers looked longer at the ambiguous words than control words when the preceding context instantiated the subordinate meaning. More importantly, the magnitude of the subordinate bias effect was the same when global context alone, local context alone, or local and global context combined were consistent with the subordinate meaning of the ambiguous word. The results of this study indicate that global contextual information (1) has an immediate impact on lexical ambiguity resolution when no local disambiguating information is available, (2) has no additional effect when it is consistent with local information, but (3) does have a slightly delayed effect when inconsistent with local information.     

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。     

不同认知方式个体抑制歧义词不适当意义的机制

本试验采用固定速的移动窗口范式和意义适合性判断任务,考察场依存、场独立个体抑制句子中歧义词不适当意义的机制以及歧义词歧义消解的进程。结果表明：不同认知方式个体在抑制句子中歧义词不适当意义的时间进程上存在差异,与场依存者相比,场独立者能够较早地抑制歧义的干扰;同时,本研究证明歧义词的多个意义首先激活,然后与语境不一致的意义得到抑制,研究结果支持词汇歧义消解的多重通达模型。     

The study of inhibitory processes in aging with the Faust et al. paradigm (1997): methodological issues

Information provided by a word activates various potential meanings. Comprehension involves the suppression of inappropriate meanings of ambiguous words in order to finetune the intended meaning of sentences. If older adults become less efficient at inhibiting contextually irrelevant information, then multiple meanings of ambiguous words would be activated regardless of contextual bias. An alternative to multiple access was that older adults activate only the most dominant meaning of ambiguous words. According to this reservation, support for an inhibition deficit would require evidence that older adults activated the multiple meanings of ambiguous words. The effects of aging on both activation and inhibition of different meanings of ambiguous words were studied using Faust et al. (1997) paradigms. Results showed that both activation and inhibition response latency differed for the dominant and subordinate target and that the dominant meaning for one subject was not the same for another one. The implication of these results is that studies of inhibition should take dominance meaning of ambiguous word for each subject into account.     

THE EFFECT OF MEANING FREQUENCY ON PROCESSING LEXICALLY AMBIGUOUS WORDS: Evidence From Eye Fixations

Abstract —Subjects read sentences containing lexically ambiguous words while their eye movements were monitored Biased ambiguous words (those that have one highly dominant sense) were used m sentences containing a prior context that instantiated their subordinate sense Control words were matched m frequency both to the dominant and to the subordinate meaning of the ambiguous word (high- and low-frequency controls) Subjects fixated longer on both the ambiguous word and the low-frequence control than on the high-frequency control When the target was ambiguous, however, the duration of posttarget fixations was longer and the likelihood of making a regression to the target was greater than when the target was an unambiguous control The results are discussed m relation to current models of lexical ambiguity resolution     

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.     

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.     

Sentential and discourse topic effects on lexical ambiguity processing: an eye movement examination

Models of lexical ambiguity resolution posit a role for context, but this construct has remained relatively undefined in the literature. The present study isolated two different forms of contextual constraint and examined how these sources of information might differentiate between a selective access and a reordered access model of ambiguity processing. Eye movements were monitored as participants read passages that contained either a balanced or a biased ambiguous word. The sentence containing the ambiguous word was held constant and instantiated either the subordinate meaning (Experiment 1) or the dominant meaning (Experiment 2) through the use of local context. These sentences were embedded in passages in which the topic was consistent, inconsistent, or neutral with respect to the meaning biased by the critical sentence. Experiment 1 provided evidence suggesting that the subordinate meaning of an ambiguous word was not selectively accessed even when sentence and discourse topic information biased that meaning. The data from Experiment 2 provided evidence that even the dominant meaning was not selectively accessed. These contextual sources of information were evaluated in terms of the roles they play in models of lexical ambiguity resolution.     

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。     

Prior context and the perception of lexically ambiguous sentences

The perceptual complexity of lexically ambiguous and unambiguous sentences was compared in three experiments. In Experiment 1, the report of ambiguous words from rapidly presented ambiguous sentences was worse than the report of corresponding unambiguous words from unambiguous sentences. Results of Experiment 2 showed that the effect was not reduced by the presence of prior biasing context within the sentence. Experiment 3 repeated the finding with a sentence meaning classification task. It was concluded that both meanings of a lexically ambiguous sentence must be computed, even when prior context makes one meaning more plausible than the other.     

The influence of global discourse on lexical ambiguity resolution

The influence of global discourse on the resolution of lexical ambiguity was examined in a series of naming experiments. Two-sentence passages were constructed to bias either the dominant or the subordinate meaning of a homonym that was embedded in a locally ambiguous sentence. The results provided evidence for the immediate (0-msec interstimulus interval) resolution of lexical ambiguity and were subsequently replicated in Experiment 2, in which an 80-msec stimulus onset asynchrony exposure duration was employed for the homonyms. Strong dominant and subordinate biased discourse contexts activated only the contextually appropriate sense of a homonym. In Experiment 3, each sentence of the discourse was presented in isolation. The pattern of activation obtained in Experiments 1 and 2 was found to be contingent on the integration of the two sentences to construct an overall global discourse representation of the text. The results support a context-sensitive model of lexical ambiguity resolution.     

Selection mechanisms in reading lexically ambiguous words

Readers' eye movements were monitored as they read sentences containing lexically ambiguous words. The ambiguous words were either biased (one strongly dominant interpretation) or nonbiased. Readers' gaze durations were longer on nonbiased than biased words when the disambiguating information followed the target word. In Experiment 1, reading times on the disambiguating word did not differ whether the disambiguation followed the target word immediately or occurred several words later. In Experiment 2, prior disambiguation eliminated the long gaze durations on nonbiased target words but resulted in long gaze durations on biased target words if the context demanded the subordinate meaning. The results indicate that successful integration of one meaning with prior context terminates the search for alternative meanings of that word. This results in selective (single meaning) access when integration of a dominant meaning is fast (due to a biasing context) and identification of a subordinate meaning is slow (a strongly biased ambiguity with a low-frequency meaning).