Early integration of context during lexical access of homonym meanings

Evidence that lexical access is guided by context was obtained using a cross-modal, semantic priming paradigm. Subjects heard homonyms presented in context that favored only one meaning and made lexical decisions to contextually appropriate, inappropriate, or unrelated target words that were presented visually. In Experiment 1, responses were facilitated for only the contextually appropriate targets, at both 50 and 200 ms interstimulus intervals. In Experiment 2, the range of interstimulus intervals was increased and subjects were encouraged to consider multiple meanings of homonyms. Even with this orientation, lexical decisions were facilitated for only the contextually appropriate targets. This pattern of selective access was maintained across the full-time course of automatic activation, suggesting that the lexicon operates interactively rather than autonomously. These findings indicate that multiple, context-independent access of word meanings should not continue to be viewed as a mandatory operation of the language comprehension system. This research was conducted as part of a doctoral dissertation submitted to the University of California, Los Angeles. The Chair of the dissertation committee, Thomas D. Wickens, was especially helpful and supportive during every stage of this project. The assistance provided by committee members (Patricia Cheng, Victoria Fromkin, Eric Holman, Donald MacKay, and John Schumann) is also appreciated.     

Hemispheric contributions to lexical ambiguity resolution in a discourse context: evidence from individuals with unilateral left and right hemisphere lesions

In the present study, a cross-modal semantic priming task was used to investigate the ability of left-hemisphere-damaged (LHD) nonfluent aphasic, right-hemisphere-damaged (RHD) and non-brain-damaged (NBD) control subjects to use a discourse context to resolve lexically ambiguous words. Subjects first heard four-sentence discourse passages ending in ambiguous words and after an inter-stimulus interval (ISI) of either 0 or 750 ms, made lexical decisions on first- or second-meaning related visual targets. NBD control subjects, at the 0 ms ISI, only activated contextually appropriate meanings, though significant effects, as a group, were only seen in second-meaning biased contexts. Surprisingly, at the 750 ms ISI, these subjects activated both appropriate and inappropriate meanings in first-meaning biased contexts. With respect to the LHD nonfluent aphasic patients, the majority activated first meanings regardless of context at the 0 ms ISI, though effects for the group were not significant. At the 750 ms ISI, these patients again activated first meanings regardless of context, with significant effects for the group only seen in first-meaning biased contexts. With regard to the RHD patients, the majority activated second meanings regardless of context at the 0 ms ISI and first meanings regardless of context at the 750 ms ISI, though, as a group, the effects were not significant. In light of our previous findings (Grindrod & Baum, 2003, submitted), the present data are interpreted as supporting the notion that damage to the left hemisphere disrupts either lexical access processes or the time course of lexical activation, whereas damage to the right hemisphere impairs the use of context and leads to activation of ambiguous word meanings based on meaning frequency.     

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.     

Sensitivity to local sentence context information in lexical ambiguity resolution: evidence from left- and right-hemisphere-damaged individuals

Using a cross-modal semantic priming paradigm, the present study investigated the ability of left-hemisphere-damaged (LHD) nonfluent aphasic, right-hemisphere-damaged (RHD) and non-brain-damaged (NBD) control subjects to use local sentence context information to resolve lexically ambiguous words. Critical sentences were manipulated such that they were either unbiased, or biased toward one of two meanings of sentence-final equibiased ambiguous words. Sentence primes were presented auditorily, followed after a short (0 ms) or long (750 ms) interstimulus interval (ISI) by the presentation of a first- or second-meaning related visual target, on which subjects made a lexical decision. At the short ISI, neither patient group appeared to be influenced by context, in sharp contrast to the performance of the NBD control subjects. LHD nonfluent aphasic subjects activated both meanings of ambiguous words regardless of context, whereas RHD subjects activated only the first meaning in unbiased and second-meaning biased contexts. At the long ISI, LHD nonfluent aphasic subjects failed to show evidence of activation of either meaning, while RHD individuals activated first meanings in unbiased contexts and contextually appropriate meanings in second-meaning biased contexts. These findings suggest that both left (LH) and right hemisphere (RH) damage lead to deficits in using local contextual information to complete the process of ambiguity resolution. LH damage seems to spare initial access to word meanings, but initially impairs the ability to use context and results in a faster than normal decay of lexical activation. RH damage appears to initially disrupt access to context, resulting in an over-reliance on frequency in the activation of ambiguous word meanings.     

Understanding metaphors: Is the right hemisphere uniquely involved?

Two divided visual field priming experiments examined cerebral asymmetries for understanding metaphors varying in sentence constraint. Experiment 1 investigated ambiguous words (e.g., SWEET and BRIGHT) with literal and metaphoric meanings in ambiguous and unambiguous sentence contexts, while Experiment 2 involved standard metaphors (e.g., The drink you gave me was a meteor) with sententially consistent and inconsistent targets (i.e., POTENT vs COMET). Similar literal and metaphor priming effects were found in both visual fields across most experimental conditions. However, RH processes also maintained activation of sententially inconsistent literal meanings following metaphoric expressions. These results do not strongly support the RH as the preferred substrate for metaphor comprehension (e.g., ), and suggest that processes in both hemispheres can support metaphor comprehension, although not via identical mechanisms. The LH may utilize sentence constraint to select and integrate only contextually relevant literal and metaphoric meanings, whereas the RH may be less sensitive to sentence context and can maintain the activation of some alternative interpretations. This may be potentially useful in situations where an initial understanding must be revised.     

Sentence context effects on lexically ambiguous words: Evidence for a postaccess inhibition process

Two experiments were conducted to investigate the process involved in selecting the contextually appropriate meaning of a homograph. Both experiments employed a grammaticality decision task. In Experiment 1, the primary (more frequent) and secondary (less frequent) meanings of homographs were used as the target items requiring a “yes” decision. The results indicated that the effect of relative frequency of these meanings of homographs was reduced when the target word was preceded either by a semantically congruous or anomalous sentence context relative to when it was preceded by the grammatical morpheme “the” or “to.” Experiment 2 indicated that “no” decisions were consistently slower for syntactically unambiguous, but semantically ambiguous words (e.g., ORGAN, FEET) than for syntactically and semantically unambiguous words (e.g., CENT, LEND), irrespective of the type of preceding context. The results, taken as a whole, are best interpreted within the postaccess inhibition model of sentence-context effects suggested by Forster (1981).     

University of Alberta norms of relative meaning frequency for 566 homographs

For many models of lexical ambiguity resolution, relative frequency of the different meanings of homographs (words with more than one meaning) is crucial. Although several homograph association norms have been published in the past, none has involved a large number of subjects responding to a large number of homographs, and most homograph norming studies are now at least a decade old. In Experiment l, associations to 566 homographs were collected from an average of 192 subjects per homograph. Frequency of occurrence for the three most common meanings is reported, along with the corresponding associates, and a measure of the overall ambiguity of each homograph. Homographs whose meanings differed in part of speech were more ambiguous overall than homographs whose different meanings belonged to a single grammatical class. Homographs whose pronunciation depended on meaning (heterophones) were no more ambiguous than nonheterophones, and word frequency was unrelated to overall ambiguity. Estimates of homograph balance across different norming studies were compared, and homographs with two meanings of approximately equal relative meaning frequency (balanced homographs) and homographs with one clearly dominant meaning (polarized homographs) were identified. In Experiment 2, reliability of meaning categorizations was measured for a subset of the homographs in the first experiment. Meaning categorizations were shown to be highly reliable across raters.     

汉语同音歧义词歧义消解的过程及其抑制机制

两个实验分别采用词语境或句子语境探讨汉语同音歧义词(homophones)歧义消解的过程。被试为112名大学生。实验通过有计划地比较不同语境偏向条件下有关探测词和无关探测词之间反应时的差异,从而揭示汉语同音歧义词消解过程中,对其适当意义激活以及对其不适当意义抑制的时间进程。两个实验的结果都表明：在同音歧义词加工的早期,语境的作用主要表现为抑制歧义词不适当意义,阻止其激活;随后,语境促进了歧义词适当意义的激活。另外,相对意义频率在同音歧义词歧义消解过程中有其影响。     

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.     

Revisiting effects of contextual strength on the subordinate bias effect: Evidence from eye movements

In this study, we examined two issues regarding the role of context in ambiguity resolution: whether access to the contextually appropriate meaning is exhaustive or selective, and whether the contextually inappropriate meaning is inhibited. Participants read texts in which a biased ambiguous word was encountered twice while their eye movements were measured. The context preceding the first encounter varied in the extent to which the subordinate meaning was supported; the context preceding the second encounter always supported the dominant meaning. The findings suggest that lexical access is exhaustive but can be influenced by context, and that the subsequent accessibility of the contextually inappropriate meaning is unaffected by previous selection processes. The results were interpreted in terms of the assumptions of the reordered-access model and activation mechanisms that operate during reading.     

Suppressing irrelevant information: knowledge activation or inhibition?

In 3 experiments, the authors examined the role of knowledge activation in the suppression of contextually irrelevant meanings for ambiguous homographs. In Experiments 1 and 2, participants with greater baseball knowledge, regardless of reading skill, more quickly suppressed the irrelevant meaning of ambiguous words in baseball-related, but not general-topic, sentences. Experiment 3 demonstrated that participants with greater general knowledge, regardless of reading skill, more quickly suppressed the irrelevant meaning of the ambiguous words in general-topic sentences. As predicted by D. S. McNamara's (1997) knowledge-based account of suppression, ambiguity effects are influenced by greater activation of knowledge related to the intended meaning of the homograph. These results challenge inhibition (e.g. M. A. Gernsbacher, K. R. Varner. & M. Faust, 1990) as the sole mechanism responsible for the suppression of irrelevant information.     

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.     

Hemispheric sensitivities to lexical and contextual information: evidence from lexical ambiguity resolution

The present study examined the manner in which both hemispheres utilize prior semantic context and relative meaning frequency during the processing of homographs. Participants read sentences biased toward the dominant or the subordinate meaning of their final homograph, or unbiased neutral sentences, and performed a lexical decision task on lateralized targets presented 250ms after the onset of the sentence-final ambiguous prime. Targets were either related to the dominant or the subordinate meaning of the preceding homograph, or unrelated to it. Performance asymmetry was found in the absence of a biasing context: dominant-related targets were exclusively facilitated in the RVF/LH, whereas both dominant- and subordinate-related targets were facilitated in the LVF/RH. Performance symmetry was found in the presence of a biasing context: dominant-related targets were exclusively activated in dominant-biasing contexts, whereas both dominant- and subordinate-related targets were facilitated in subordinate-biasing contexts. The implications of the results for both general and hemispheric models of word processing are discussed.     

Processing novel compounds: Evidence for interactive meaning activation of ambiguous nouns

In three experiments, the meaning activation of ambiguous nouns in novel nominal compounds was investigated. Ambiguous nouns were unbalanced homographs occurring as the second members of the compound. Meaningful interpretations of the compounds were based on either the dominant or the subordinate meaning of the ambiguous noun. In Experiment 1, visually presented novel compounds serving as primes were followed at varying intervals by targets associatively related to distinct meanings of the ambiguous noun. In a lexical decision task, facilitation effects were found only for targets related to the meaning that was relevant for the interpretation of the compound. Experiment 2 showed that interactive activation could not be attributed to differences in semantic relatedness between the first members of compounds and targets. Experiment 3 demonstrated equal intralexical relatedness between members for both types of compounds. It is proposed that interactive activation may facilitate the interpretation of the novel compound. Compatible meaning aspects of the nouns may become more strongly activated, and incompatible meaning aspects may not become activated. The selection of meaning aspects relevant for interpretation would thereby be simplified.     

Processing homonymy and polysemy: effects of sentential context and time-course following unilateral brain damage

The present study investigated the abilities of left-hemisphere-damaged (LHD) non-fluent aphasic, right-hemisphere-damaged (RHD), and normal control individuals to access, in sentential biasing contexts, the multiple meanings of three types of ambiguous words, namely homonyms (e.g., "punch"), metonymies (e.g., "rabbit"), and metaphors (e.g., "star"). Furthermore, the predictions of the "suppression deficit" and "coarse semantic coding" hypotheses, which have been proposed to account for RH language function/dysfunction, were tested. Using an auditory semantic priming paradigm, ambiguous words were incorporated in dominant- or subordinate-biasing sentence-primes followed after a short (100 ms) or long (1,000 ms) interstimulus interval (ISI) by dominant-meaning-related, subordinate-meaning-related or unrelated target words. For all three types of ambiguous words, both the effects of context and ISI were obvious in the performance of normal control subjects, who showed multiple meaning activation at the short ISI, but eventually, at the long ISI, contextually appropriate meaning selection. Largely similar performance was exhibited by the LHD non-fluent aphasic patients as well. In contrast, RHD patients showed limited effects of context, and no effects of the time-course of processing. In addition, although homonymous and metonymous words showed similar patterns of activation (i.e., both meanings were activated at both ISIs), RHD patients had difficulties activating the subordinate meanings of metaphors, suggesting a selective problem with figurative meanings. Although the present findings do not provide strong support for either the "coarse semantic coding" or the "suppression deficit" hypotheses, they are viewed as being more consistent with the latter, according to which RH damage leads to deficits suppressing alternative meanings of ambiguous words that become incompatible with the context.     

READING SKILL AND SUPPRESSION REVISITED

Abstract— In a previous issue of Psychological Science, we (Gernsbacher, 1993) reported that less skilled readers are less able than more skilled readers to quickly suppress irrelevant information (e.g., the contextually inappropriate meaning of a homonym, such as the playing-card meaning of spade, in the sentence He dug with the spade, or the inappropriate form of a homophone, such as patience, in the sentence He had lots of patients). In the current research, we investigated a ramification of that finding. If less skilled readers are less able to suppress a contextually inappropriate meaning of a homonym, perhaps less skilled readers might be better than more skilled readers at comprehending puns. However, intuition and previous research suggest the contrary, as do the results of the research presented here. On a task that required accepting, rather than rejecting, a meaning of a homonym that was not implied by the sentence context, more skilled readers responded more rapidly than less skilled readers. In contrast, on a task that required accepting a meaning of a homonym that was implied by the sentence context, more and less skilled readers performed equally well. We conclude that more skilled readers are more able to rapidly accept inappropriate meanings of homonyms because they are more skilled at suppression (which in this case involves suppressing the appropriate meanings).     

Rapid extraction of gist from visual text and its influence on word recognition

Two experiments explored rapid extraction of gist from a visual text and its influence on word recognition. In both, a short text (sentence) containing a target word was presented for 200 ms and was followed by a target recognition task. Results showed that participants recognized contextually anomalous word targets less frequently than contextually consistent counterparts (Experiment 1). This context effect was obtained when sentences contained the same semantic content but with disrupted syntactic structure (Experiment 2). Results demonstrate that words in a briefly presented visual sentence are processed in parallel and that rapid extraction of sentence gist relies on a primitive representation of sentence context (termed protocontext) that is semantically activated by the simultaneous presentation of multiple words (i.e., a sentence) before syntactic processing.     

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。     

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。