Underspecification of syntactic ambiguities: Evidence from self-paced reading

Syntactically ambiguous sentences are sometimes read faster than disambiguated strings. Models of parsing have explained this tendency by appealing either to a race in the construction of alternative structures or to reanalysis. However, it is also possible that readers of ambiguous sentences save time by strategically underspecifying interpretations of ambiguous attachments. In a self-paced reading study, participants viewed sentences with relative clauses that could attach to one of two sites. Type of question was also manipulated between participants in order to test whether goals can influence reading/parsing strategies. The experiment revealed an ambiguity advantage in reading times, but only when participants expected superficial comprehension questions. When participants expected queries about relative clause interpretation, disambiguating regions were inspected with more care, and the ambiguity advantage was attenuated. However, even when participants expected relative clause queries, question-answering times suggested underspecified representations of ambiguous relative clause attachments. The results support the construal and "good-enough" models of parsing.     

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。     

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     

Ambiguity Advantage Revisited: Two Meanings are Better than One When Accessing Chinese Nouns

This paper revisits the effect of lexical ambiguity in word recognition, which has been controversial as previous research reported advantage, disadvantage, and null effects. We discuss factors that were not consistently treated in previous research (e.g., the level of lexical ambiguity investigated, parts of speech of the experimental stimuli, and the choice of non-words) and report on a lexical decision experiment with Chinese nouns in which ambiguous nouns with homonymic and/or metaphorical meanings were contrasted with unambiguous nouns. An ambiguity advantage effect was obtained—Chinese nouns with multiple meanings were recognized faster than those with only one meaning. The results suggested that both homonymic and metaphorical meanings are psychologically salient semantic levels actively represented in the mental lexicon. The results supported a probability-based model of random lexical access with multiple meanings represented by separate semantic nodes. We further discuss these results in terms of lexical semantic representation and how different experimental paradigms result in different ambiguity effects in lexical access.     

In search of ambiguity

A study of the time required for Ss to perceive the two meanings of ambiguous sentences, supports the following conclusions: (I) Perception time (PT) is a function of the type of ambiguity, three of which are defined in this study. (2) A similar relative function was obtained for thePT in sentences with more than one ambiguity and for sentences with only a single ambiguity. (3) ThePT for finding a single ambiguity in such multiply ambiguous sentences was significantly longer than in singly ambiguous sentences. (4) When one of the interpretations of certain types of ambiguous sentences is less likely than the other (where likeliness is defined in terms of the number of Ss perceiving that inter-pretation first)PT is high. (5) Complexity of the surface and underlying structures (which are defined in transformational grammar) is an important determinant of thePT for surface and underlying structure ambiguities, respectively.     

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.     

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).     

Accessing lexical ambiguities during sentence comprehension: Effects of frequency of meaning and contextual bias

Two hypotheses concerning the nature of lexical access, the exhaustive access and the terminating ordered search hypotheses, were examined in two separate studies using a crossmodal lexical priming task. In this task, subjects listened to sentences that were biased toward either the primary interpretation (a meaning occurring 75% or more of the time) or a secondary interpretation (a meaning occurring less than 25% of the time) of a lexical ambiguity that occurred in each sentence. Simultaneously, subjects made lexical decisions about visually presented words. Decisions to words related to both the primary and secondary meanings of the ambiguity were facilitated when presented immediately following occurrence of the ambiguity in the sentence. This effect held under each of the two biasing context conditions. However, when they were presented 1.5 sec following occurrence of the ambiguity, only visual words related to the contextually relevant meaning of the ambiguity were facilitated. These results support the exhaustive access hypothesis. It is argued that lexical access is an autonomous subsystem of the sentence comprehension routine in which all meanings of a word are momentarily accessed, regardless of the factors of contextual bias or bias associated with frequency of use.     

Interpretive cues and ambiguity in generalized anxiety disorder

The current study investigated whether generalized anxiety disorder (GAD) individuals rely on antecedent information to interpret ambiguity and whether reliance on such preceding cues persists in the absence of potential threat. Twenty-six GAD and 23 nonanxious control college students performed a lexical decision task, using homographs (i.e. words with multiple meanings) as ambiguous primes. In half the trials, a homograph prime that possessed both threat-related, as well as neutral meanings was followed by a target word related to one of these two meanings. In addition, each ambiguous prime was immediately preceded by a series of four antecedent words that were either: (a) associated with the threatening meaning of the prime; (b) associated with the neutral meaning of the prime; or (c) unrelated to either meaning of the homograph, as well as the target. Homographs for which both meanings were neutral in valence comprised the other half of the trials. Effect size statistics suggest that GAD participants utilized the antecedent words to interpret the homograph primes with threat-related meanings, unlike their nonanxious counterparts (p<0.06). When both meanings of the homograph prime were neutral in valence, the GAD group appeared deficient in the use of preceding information to interpret the ambiguous prime.     

Effects of syntactic category assignment on lexical ambiguity resolution in reading: an eye movement analysis

Readers' eye movements were monitored as they read sentences containing lexically ambiguous words whose meanings share a single syntactic category (e.g., calf), lexically ambiguous words whose meanings belong to different syntactic categories (e.g., duck), or unambiguous control words. Information provided prior to the target always unambiguously specified the context-appropriate syntactic-category assignment for the target. Fixation times were longer on ambiguous words whose meanings share a single syntactic category than on controls, both when prior context was semantically consistent with the subordinate interpretation of a biased ambiguous word (Experiment 1) and when prior context was semantically neutral as to the intended interpretation of a balanced ambiguous word (Experiment 2). These ambiguity effects, which resulted from differences in difficulty with meaning resolution, were not found when the ambiguity crossed syntactic categories. These data indicate that, in the absence of syntactic ambiguity, syntactic-category information mediates the semantic-resolution process.     

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.     

Multiple semantic encoding of homophones and homographs in contexts biasing dominant or subordinate meanings

The resolution of lexical ambiguity was studied in two experiments. While subsequent selection would appear to limit longer term storage to one meaning of an ambiguous word, multiple initial encoding of homophones and homographs was indicated by the intrusion of their alternative meanings across trials in a Brown-Peterson paradigm. In Experiment 1 subjects heard four words and then engaged in a 10osec distractor task. Written recall was then demanded. On context trials a homophone with two distinct alternative meanings was presented with other words biasing either a dominant or subordinate meaning, for example, look, stare,peer, glance. On the next trial words related to an alternative meaning were presented, for example, dock, wharf, quay, jetty. Intrusions of the graphic forms of alternative meanings le.g.,PIER) into critical trial recall occurred whether the dominant or subordinate meaning of the homophone had been biased by context. Experiment 2 employed visual presentation of homographs, for example, GOLD, IRON,LEAD, and oral recall, but was logically similar to Experiment 1. Intrusions of the alternative codings of homographs across trials again occurred, for example, GUIDE, DIRECT,lead, regardless of the meaning originally biased by context.     

Aspectual Coercion in Eye Movements

Comprehension includes interpreting sentences in terms of aspectual categories such as processes (Harry climbed) and culminations (Harry reached the top). Adding a verbal modifier such as for many years to a culmination coerces its interpretation from one to many culminations. Previous studies have found that coercion increases lexical decision and meaning judgment time, but not eye fixation time. This study recorded eye movements as participants read sentences in which a coercive adverb increased the interpretation of multiple events. Adverbs appeared at the end of a clause and line; the post-adverb region appeared at the beginning of the next line; follow-up questions occasionally asked about aspectual meaning; and clause type varied systematically. Coercive adverbs increased eye fixation time in the post-adverb region and in the adverb and post-adverb regions combined. Factors that influence the appearance of aspectual coercion may include world knowledge, follow-up questions, and the location and ambiguity of adverbs.     

Contextual Strength and the Subordinate Bias Effect: Comment on Martin, Vu, Kellas, and Metcalf

Martin, Vu, Kellas, and Metcalf (this issue) claim to have demonstrated that the subordinate bias effect (when preceding context instantiates the subordinate meaning of an ambiguous word that has a highly dominant meaning, reading time on that word is lengthened) can be eliminated by strong context. They argue that this provides evidence critical to discriminating between competing models of lexical ambiguity resolution: the reordered access model (in which access of meanings for an ambiguous word is exhaustive but in which the order of access is influenced by prior disambiguating context) and the context-sensitive model (in which access is selective in the presence of prior disambiguating information). We argue that there are methodological problems with their demonstration, but even if there were not, it is unclear that the subordinate bias effect is appropriate for discriminating between competing models of lexical ambiguity resolution (the reordered access model and the context-sensitive model). The effect is an empirical finding and not a fundamental tenet of the reordered access model.     

The comprehension and verification of ambiguous sentences

When Ss are presented with an ambiguous sentence they tend to interpret it in only one way. If later events warrant, Ss can recover the other meaning, a process which takes time. These conclusions follow from the results of a study in which 40 undergraduate Ss verified whether or not pictures shown at the end of a sentence represented the meaning of the sentence. When ambiguous sentences were presented, the verification time (VT) was no slower than for unambiguous sentences if the picture represented the “expected” meaning (as determined on a pre-test) of the ambiguity. The VT to the picture representing the “unexpected” meaning of the ambiguity was longer than VT to corresponding control sentences.     

To end ambiguous sentences

A study of the time required to complete ambiguous sentences suggested that: even though Ss are unaware of the ambiguity while completing sentences, they take more time to complete ambiguous sentences than unambiguous ones: the degree of difficulty in completing ambiguous sentences is related to the linguistic level at which the ambiguity occurs: sentences containing two ambiguities are more difficult to complete than those containing only one, and when these two ambiguities occur at different linguistic levels, these sentences are harder to complete than when both occur within the same linguistic level: ambiguity may affect the grammaticality and relevance of completions; and may cause stuttering and laughter, even without awareness of the ambiguity. An attempt to fit these results to several theories of the processing of ambiguous sentences led us to the conclusion that ambiguity interferes with our understanding of a single meaning of a sentence, and that the degree of interference varies with the linguistic level at which the ambiguity occurs.     

Cognitive Bias Modification: The Critical Role of Active Training in Modifying Emotional Responses

Training participants to select threat or nonthreat interpretations of emotionally ambiguous stimuli or passively exposing them to valenced scenarios can modify later interpretation of ambiguity. However, only when encouraged to actively select meanings do congruent changes in emotional response occur during training itself (Mathews & Mackintosh, 2000). The present study assessed the more critical question of whether active training is also necessary for modifying subsequent emotional responses to images of new ambiguous scenarios presented after training. As predicted, active training did lead participants to rate their images of emotionally ambiguous scenarios as being more unpleasant after training as compared to a matched passive condition. This finding supports the view that active generation of meaning during interpretive training is critical for the modification of later emotional responses.     

To end ambiguous sentences

A study of the time required to complete ambiguous sentences suggested that: even though Ss are unaware of the ambiguity while completing sentences, they take more time to complete ambiguous sentences than unambiguous ones: the degree of difficulty in completing ambiguous sentences is related to the linguistic level at which the ambiguity occurs: sentences containing two ambiguities are more difficult to complete than those containing only one, and when these two ambiguities occur at different linguistic levels, these sentences are harder to complete than when both occur within the same linguistic level: ambiguity may affect the grammaticality and relevance of completions; and may cause stuttering and laughter, even without awareness of the ambiguity. An attempt to fit these results to several theories of the processing of ambiguous sentences led us to the conclusion that ambiguity interferes with our understanding of a single meaning of a sentence, and that the degree of interference varies with the linguistic level at which the ambiguity occurs.     

Influence of context on the activation and selection of ambiguous word senses

The activation of ambiguous word senses was investigated by measuring the amount of interference in naming the ink color of a word that was either related or unrelated to one of the meanings of a preceding ambiguous word. In agreement with previous results obtained using this procedure (Conrad, 1974), evidence was obtained that both meanings of the ambiguous words are activated even in the presence of biasing context. However, contrary to previous findings, the degree of activation of each word sense depended on its degree of compatibility with the context. These results are consistent with a language processing system in which all interpretations of an ambiguity are accessed and then processed until an accurate determination has been made of which interpretation best satisfies the syntactic and semantic constraints that govern it.     

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。