The lexical nature of syntactic ambiguity resolution.

Ambiguity resolution is a central problem in language comprehension. Lexical and syntactic ambiguities are standardly assumed to involve different types of knowledge representations and be resolved by different mechanisms. An alternative account is provided in which both types of ambiguity derive from aspects of lexical representation and are resolved by the same processing mechanisms. Reinterpreting syntactic ambiguity resolution as a form of lexical ambiguity resolution obviates the need for special parsing principles to account for syntactic interpretation preferences, reconciles a number of apparently conflicting results concerning the roles of lexical and contextual information in sentence processing, explains differences among ambiguities in terms of ease of resolution, and provides a more unified account of language comprehension than was previously available. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An investigation of working memory influences on lexical ambiguity resolution.

The present study employed a combined semantic judgment and lexical decision priming paradigm to examine the impact of working memory on the inhibitory processes of lexical ambiguity resolution. The results indicated that overall, participants activated one meaning of a presented homograph while not priming the alternative meaning. As hypothesized, participants with high working-memory spans exhibited a pattern of priming for congruent conditions and a lack of positive priming for incongruent conditions. In contrast, participants with low working-memory capacity showed priming for both congruent and incongruent conditions, but only for conditions in which the context was related to the dominant meaning of the homograph. The results suggest that people with low working-memory capacity have difficulty inhibiting inappropriate homograph meanings and further demonstrate that these difficulties may vary as a function of context-meaning dominance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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.     

Context and lexical access: Implications of nonword interference for lexical ambiguity resolution.

To eliminate potential "backward" priming effects, S. Glucksberg et al (see record 1986-29080-001) introduced a variant of the cross-modal lexical priming task in which subjects made lexical decisions to nonword targets that were modeled on a word related to either the contextually biased or unbiased sense of an ambiguous word. Lexical decisions to nonwords were longer than controls only when the nonword was related to the contextually biased sense of the ambiguous word, leading Glucksberg et al to conclude that context does constrain lexical access and that the multiple access pattern observed in previous studies was probably an artifact of backward priming. We did not find nonword interference when the nonword targets used by Glucksberg et al were preceded by semantically related ambiguous or unambiguous word primes. However, we did replicate their sentence context results when the ambiguous words were removed from the sentences. We conclude that the interference obtained by Glucksberg et al is due to postlexical judgments of the congruence of the sentence context and the target, not to context constraining lexical access. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prosodic influences on the resolution of temporary ambiguity during on-line sentence processing

We present three experiments designed to investigate the role of prosody during sentence processing. The first investigated the question of whether an utterance's prosodic contour influences its comprehension on-line. We spliced the beginning and end portions of direct object and embedded clause sentences and observed the consequent effects on comprehension using a dual-task procedure to measure processing load. Our second experiment sought to determine whether the constituent structure of these sentences could be reliably predicted using prosodic information. We found that the duration and F0 contour associated with the main-clause verb and the following NP reliably distinguished between the direct object and embedded clause constructions. In the final experiment, we manipulated the duration of the main-clause verb and found that subjects used this information to guide their initial parse during on-line sentence comprehension. The need for a model of sentence processing that addresses the use of prosodic information is discussed.     

Eye movements and lexical ambiguity resolution: Investigating the subordinate-bias effect.

Recent debates on lexical ambiguity resolution have centered on the subordinate-bias effect, in which reading time is longer on a biased ambiguous word in a subordinate-biasing context than on a control word. The nature of the control word--namely, whether it matched the frequency of the ambiguous word's overall word form or its contextually instantiated word meaning (a higher or lower frequency word, respectively)--was examined. In addition, contexts that were singularly supportive of the ambiguous word's subordinate meaning were used. Eye movements were recorded as participants read contextually biasing passages that contained an ambiguous word target or a word-form or word-meaning control. A comparison of fixation times on the 2 control words revealed a significant effect of word frequency. Fixation times on the ambiguous word generally fell between those on the 2 controls and were significantly different than both. Results are discussed in relation to the reordered access model, in which both meaning frequency and prior context affect access procedures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Eye movements and lexical ambiguity resolution: Effects of prior encounter and discourse topic.

Eye movements were monitored as participants read passages that contained 2 occurrences of a balanced ambiguous word. In Experiment 1, local context was manipulated so that the meaning of the ambiguous word either remained the same or changed from the 1st to 2nd encounter. In Experiments 2 and 3, global context was manipulated by shifting the discourse topic between the 2 instances of the ambiguous word. Gaze durations on the 2nd instance of the ambiguous word were shorter when the meaning remained consistent than when the meaning changed, and this facilitation was impervious to changes in the discourse structure. In contrast, processing time in the region immediately following the target was longer when the word meaning changed, but only when the topic of the discourse remained the same throughout the passage. When the topic was shifted, this effect disappeared. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Syntactic ambiguity resolution in discourse: Modeling the effects of referential context and lexical frequency.

Sentences with temporarily ambiguous reduced relative clauses (e.g., The actress selected by the director believed that …) were preceded by discourse contexts biasing a main clause or a relative clause. Eye movements in the disambiguating region (by the director) revealed that, in the relative clause biasing contexts, ambiguous reduced relatives were no more difficult to process than unambiguous reduced relatives or full (unreduced) relatives. Regression analyses demonstrated that the effects of discourse context at the point of ambiguity (e.g., selected) interacted with the past participle frequency of the ambiguous verb. Reading times were modeled using a constraint-based competition framework in which multiple constraints are immediately integrated during parsing and interpretation. Simulations suggested that this framework reconciles the superficially conflicting results in the literature on referential context effects on syntactic ambiguity resolution. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phonological ambiguity and lexical ambiguity: Effects on visual and auditory word recognition.

Three experiments in Serbo-Croatian were conducted on the effects of phonological ambiguity and lexical ambiguity on printed word recognition. Subjects decided rapidly if a printed and a spoken word matched or not. Printed words were either phonologically ambiguous (two possible pronunciations) or unambiguous. If phonologically ambiguous, either both pronunciations were real words or only one was, the other being a nonword. Spoken words were necessarily unambiguous. Half the spoken words were auditorily degraded. In addition, the relative onsets of speech and print were varied. Speed of matching print to speech was slowed by phonological ambiguity, and the effect was amplified when the stimulus was also lexically ambiguous. Auditory degradation did not interact with print ambiguity, suggesting the perception of the spoken word was independent of the printed word. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual representation as a mechanism of lexical ambiguity resolution: An investigation of span and processing time.

In 2 experiments, the authors investigated the ability of high- and low-span comprehenders to construe subtle shades of meaning through perceptual representation. High- and low-span comprehenders responded to pictures that either matched or mismatched a target object's shape as implied by the preceding sentence context. At 750 ms after hearing the sentence describing the target object, both high- and low-span comprehenders had activated a contextually appropriate perceptual representation of the target object. However, only high-span comprehenders had perceptually represented the contextually appropriate meaning immediately upon hearing the sentence, whereas low-span comprehenders required more processing time before the perceptual representation was activated. The results are interpreted in a framework of co-occurring lexical representations and perceptual-motor representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Semantic facilitation of lexical access during sentence processing.

In three experiments we investigated the effect of a sentence context on naming time for a target word. Contexts were presented by using a rapid serial visual presentation; subjects named the last word of the sentence. In the first two experiments, facilitation was observed for a fully congruent context containing a subject and verb that were weakly related to the target word. No facilitation was observed when either the subject or verb was replaced with a more neutral word. In the third experiment, the fully congruent contexts were modified either to preserve or to disrupt the original relation between the subject and verb. Facilitation was observed in both conditions. The full pattern of results suggests that a combination of lexical items can prime a target word in the absence of priming by any of the lexical items individually. This combination priming is not dependent upon the overall meaning of the sentence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does English coronal place assimilation create lexical ambiguity?

The purpose of this study was to determine how potential lexical ambiguity produced by place assimilation is resolved. Four cross-modal form priming experiments using primes in sentential contexts were performed. In the first 2, prime items had underlyingly coronal offsets (e.g., right) with assimilated noncoronal place. The primes were judged to be perceptually ambiguous (between right and ripe) in Experiment 1 and noncoronal (ripe) in Experiment 2 in off-line testing. In Experiment 3, primes were replaced with corresponding underlyingly noncoronal items (ripe). In all 3 experiments, participants showed selective priming for the underlying form of the prime. A 4th form priming experiment using the gated tokens of priming stimuli used in Experiment 2 examined the role of postlexical context on this process. In this experiment, participants showed priming for both underlying and surface forms of the prime. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of sentence constraint on priming in natural language comprehension.

In 4 cross-modal naming experiments, researchers investigated the role of sentence constraint in natural language comprehension. On the sentence constraint account, incoming linguistic material activates semantic features that in turn pre-activate likely upcoming words. The 1st and 2nd experiments investigated whether stimulus offset asynchrony played a critical role in previous studies supporting the sentence constraint account. The 3rd and 4th experiments examined further predictions of the sentence constraint account, in particular whether pre-activated words would compete for activation. In Experiment 3, the researchers manipulated whether an expected target word had a close competitor and found that response to the expected word was facilitated regardless of the proximity of a competitor. The 4th experiment established that close competitors were primed by the sentence frames and should have been available to compete with expected target words. Thus, word-level representations did not compete for activation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using cross-modal lexical decision tasks to investigate sentence processing.

Recent investigations of sentence processing have used the cross-modal lexical decision task to show that the antecedent of a phonologically empty noun phrase (specifically, WH-trace) is reactivated at the trace position. G. McKoon et al (see record 1995-04309-001) claimed that (1) a design feature concerning the choice of related and unrelated targets is a possible confound in this work and (2) the conclusions drawn from this previous research are therefore called into question. These claims are considered in light of both the McKoon et al experimental findings and the results of the J. L. Nicol et al experiments in which linguistic materials are tested. Nicol et al argue that their results may be due to the nature of their materials, and that a follow-up experiment reported by McKoon and R. Ratcliff (see record 1995-04308-001) used a technique that is not comparable to the cross-modal lexical decision task. It is concluded that current evidence supports the claim that structural information is used during on-line sentence processing and that the cross-modal technique is sensitive to this. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The interpretation of sentence ambiguity in patients with unilateral focal brain surgery

Interpretations of ambiguous sentences were studied in patients with unilateral anterior temporal lobectomy or selective amygdalo-hippocampectomy. The sentences represented lexical and syntactic ambiguities. In both left- and right-sided groups, regardless of type of surgery, total mean score on the test was below normal. Left-sided cases, regardless of type of surgery, provided significantly fewer alternative interpretations than right-sided cases. The results suggest greater left than right hemisphere specialization in both lexical and syntactic processing, but also suggest right hemisphere involvement in resolution of lexical ambiguity.     

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 subordininate 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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Structural and lexical constraints on filling gaps during sentence comprehension: A time-course analysis.

Reaction time and speed-accuracy trade-off procedures were used to examine when different linguistic constraints were operative in processing sentences with filler-gap dependencies. Experiments measured the time to assess the acceptability of structures with anomalous filler-gap dependencies stemming from violations of configuration (syntactic) constraints or local lexical constraints. Full time-course data indicate that configurational (island) constraints were operative 200–400 ms before local lexical constraints (i.e., subcategorization and thematic role restrictions). These results suggest that filler-gap assignments are determined by processes that appeal first to general syntactic information and only later to specific lexical information. The time-course data indicate that the parser does not posit potential gap sites within syntactic islands, which in turn motivates a restricted version of a first-resort model of filler-gap processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The cascaded nature of lexical selection and integration in auditory sentence processing.

An event-related brain potential experiment was carried out to investigate the temporal relationship between lexical selection and the semantic integration in auditory sentence processing. Participants were presented with spoken sentences that ended with a word that was either semantically congruent or anomalous. Information about the moment in which a sentence-final word could uniquely be identified, its isolation point (IP), was compared with the onset of the elicited N400 congruity effect, reflecting semantic integration processing. The results revealed that the onset of the N400 effect occurred prior to the IP of the sentence-final words. Moreover, the factor early or late IP did not affect the onset of the N400. These findings indicate that lexical selection and semantic integration are cascading processes, in that semantic integration processing can start before the acoustic information allows the selection of a unique candidate and seems to be attempted in parallel for multiple candidates that are still compatible with the bottom-up acoustic input. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Resolution of lexical ambiguity: Evidence from an eye movement priming paradigm.

Subjects' eye movements were monitored while they read 2-sentence passages of text. A target-word region was defined in the 2nd sentence of each passage. During the initial 35 ms of a target region eye fixation, an ambiguous word was presented as a prime. A target word subsequently replaced the prime during the fixation. Priming was measured by comparing fixation times on targets preceded by semantically related versus unrelated ambiguous primes. The type of prior context (consistent vs. inconsistent), type of ambiguous prime (biased vs. balanced), and strength of instantiated meaning (dominant vs. subordinate) could all affect priming. Priming effects were only found when the prior context was consistent with the dominant sense of a biased ambiguous prime. The results are discussed in terms of models of ambiguity resolution: The data seem most consistent with a reordered access model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Verb-specific constraints in sentence processing: Separating effects of lexical preference from garden-paths.

Immediate effects of verb-specific syntactic (subcategorization) information were found in a cross-modal naming experiment, a self-paced reading experiment, and an experiment in which eye movements were monitored. In the reading studies, syntactic misanalysis effects in sentence complements (e.g., "The student forgot the solution was…") occurred at the verb in the complement (e.g., was) for matrix verbs typically used with noun phrase complements but not for verbs typically used with sentence complements. In addition, a complementizer effect for sentence-complement-biased verbs was not due to syntactic misanalysis but was correlated with how strongly a particular verb prefers to be followed by the complementizer that. The results support models that make immediate use of lexically specific constraints, especially constraint-based models, but are problematic for lexical filtering models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)