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.     

中文句子中双音节兼类词句法分析历程初探

以既可用作名词,又可用作动词的汉语双音节兼类词为材料,采用移动窗口范式,考察了汉语句子中名词倾向性高和低两类兼类词句法分析的详细历程。结果发现,两类兼类词与各自的控制词之间,均未出现阅读时间上的显著差异,因此并不支持延迟模型所提出的兼类词句法角色延迟指派的观点。实验还发现,名词倾向性高的兼类词引起了更大的加工困难。此外,即便是名词倾向性低的兼类词,被试也仍为其指派名词的句法角色。花园路径模型和制约满意理论均不能单独和完整解释上述发现。文章指出,实验结果支持一种既不同于花园路径模型,又不同于制约满意理论的权变的理论。阅读中遇到兼类词时,读者能立即为其指派句法角色。这种指派过程既可以利用概率制约信息,也可以在句法分析原则指导下进行。句法分析原则是否起作用,取决于概率制约信息的制约强度     

句法歧义消解影响因素、认知机制及其神经基础

句法歧义消解主要是指人们在面临多种句法分析可能性的情况下,句法分析器抑制不正确的句法分析而选择正确句法分析的认知过程。研究表明,该过程受到工作记忆、认知控制能力、语言分布频率、语境、韵律等因素的影响。为有效说明人们是如何完成句法歧义消解的,研究者们建构了诸如花园路径模型、约束满意理论、弱交互作用句法分析理论等相关模型。另外,基于脑成像技术研究表明,左侧额下回、左侧颞叶后部、中部和前部在句法消歧任务中都有显著激活。未来研究当围绕着句法消歧中的语义效应、句法和词汇歧义消解机制的异同、句法消歧中抑制能力的效应等方面展开。     

A Probabilistic Model of Lexical and Syntactic Access and Disambiguation

The problems of access—retrieving linguistic structure from some mental grammar —and disambiguation—choosing among these structures to correctly parse ambiguous linguistic input—are fundamental to language understanding. The literature abounds with psychological results on lexical access, the access of idioms, syntactic rule access, parsing preferences, syntactic disambiguation, and the processing of garden-path sentences. Unfortunately, it has been difficult to combine models which account for these results to build a general, uniform model of access and disambiguation at the lexical, idiomatic, and syntactic levels. For example, psycholinguistic theories of lexical access and idiom access and parsing theories of syntactic rule access have almost no commonality in methodology or coverage of psycholinguistic data. This article presents a single probabilistic algorithm which models both the access and disambiguation of linguistic knowledge. The algorithm is based on a parallel parser which ranks constructions for access, and interpretations for disambiguation, by their conditional probability. Low-ranked constructions and interpretations are pruned through beam-search; this pruning accounts, among other things, for the garden-path effect. I show that this motivated probabilistic treatment accounts for a wide variety of psycholinguistic results, arguing for a more uniform representation of linguistic knowledge and for the use of probabilistically-enriched grammars and interpreters as models of human knowledge of and processing of language.     

Discourse influences during parsing are delayed.

Subjects read sentences containing either a syntactically ambiguous prepositional phrase attachment or a syntactically ambiguous reduced relative clause. The sentences were embedded in passages of text that were consistent with either the minimal or non-minimal attachment reading. In addition, a discourse factor (i.e., whether or not the target sentence was in the discourse focus) was varied. Subjects' eye movements were recorded as they read the passages of text. Our primary finding was that subjects were garden-pathed even when there was biasing context. However, when the target sentence was in the discourse focus, subjects were able to recover more readily from their initial erroneous parse of the sentence. The data thus support models of sentence parsing that postulate that the parsing of a sentence is based upon structurally based principles and the influence of semantic or pragmatic information makes itself felt only after the initial parsing decision has been made.     

Parsing strategies and discourse context

Two experiments investigated syntactic processing during comprehension of sentences presented either in isolation or in a discourse context. Comprehension of a range of different types of surface structurally ambiguous sentences was studied. To explain the interpretations generally given to the sentences processed in isolation, two parsing principles were proposed: Kimball's (1973) Right Association and Verb Dominance. When the ambiguous sentences were read in context, the interpretations computed were still determined by these structurally based principles, even when this meant that the meanings were at variance with the prior context. These results indicate that surface structure parsing of sentences proceeds in the same way whether sentences are processed alone or in context.This research was supported by a grant from the Australian Research Grants Scheme. I thank Linda Cupples for her help in conducting the experiments and in analyzing the data. I am indebted to Marilyn Ford for her critical comments on an earlier, version of the article. Thanks are also due to Dianne Bradley, Ken Forster, and Roger Wales for their helpful comments on the topic.     

汉语偏正/述宾歧义短语加工初探

操纵短语续接方向及歧义性,采用移动窗口范式,考察了均衡型、偏正型和述宾型三类歧义短语的加工,结果发现,偏正型歧义短语按述宾结构续接以及述宾型歧义短语按偏正结构续按时,在解歧区２上都有明显的加工困难,说明实验所采用的方法是敏感的。实验还发现,均衡型歧义短语按述宾结构续接时,在解歧区２上仍有加工上的困难,述宾型歧义短语按偏正结构续按时,在解歧区３上仍能看到加工上的困难,这表明歧义消解具有相对分散的特点。更重要的是,实验发现,均衡型歧义短语按述宾结构续接时,在解歧区１上就出现了加工困难,表明被试实际上按偏正结构来分析这种短语。该文从句法分析原则、语言分布知识的使用以及动词论题结构与语义完整性等角度对这一发现进行了讨论。     

Functional neuroanatomy of the cognitive process of mapping during discourse comprehension

We used functional magnetic resonance imaging (fMRI) to identify brain regions involved in the process of mapping coherent discourse onto a developing mental representation. We manipulated discourse coherence by presenting sentences with definite articles (which lead to more coherent discourse) or indefinite articles (which lead to less coherent discourse). Comprehending connected discourse, compared with reading unrelated sentences, produced more neural activity in the right than left hemisphere of the frontal lobe. Thus, the right hemisphere of the frontal lobe is involved in some of the processes underlying mapping. In contrast, left-hemisphere structures were associated with lower-level processes in reading (such as word recognition and syntactic processing). Our results demonstrate the utility of using fMRI to investigate the neural substrates of higher-level cognitive processes such as discourse comprehension.     

Parallel parsing: Evidence from reactivation in garden-path sentences

An all-visual, on-line, lexical priming technique was used to investigate whether the human sentence processor computes syntactic representations serially or in parallel. Structurally ambiguous garden-path sentences such as the following were studied: “The psychologist told the wife that the man bumpedthat her car was stolen.” Despite the strong preference for the sentential-complement reading of the ambiguous region (italicized), a reactivation effect for the head of the relative clause (wife) was observed immediately following the presentation of the embedded verb (bumped), suggesting that the relative clause analysis is also computed. This finding is taken as evidence for parallel parsing since both possible analyses were shown to have a processing reflection simultaneously: Computation of the sentential-complement analysis was demonstrated by the fact that readers garden-path when that analysis turns out to be incorrect, and computation of the relative clause analysis was demonstrated by the reactivation effect.     

Tracking the continuity of language comprehension: computer mouse trajectories suggest parallel syntactic processing

Although several theories of online syntactic processing assume the parallel activation of multiple syntactic representations, evidence supporting simultaneous activation has been inconclusive. Here, the continuous and non-ballistic properties of computer mouse movements are exploited, by recording their streaming x, y coordinates to procure evidence regarding parallel versus serial processing. Participants heard structurally ambiguous sentences while viewing scenes with properties either supporting or not supporting the difficult modifier interpretation. The curvatures of the elicited trajectories revealed both an effect of visual context and graded competition between simultaneously active syntactic representations. The results are discussed in the context of 3 major groups of theories within the domain of sentence processing.     

Storage and integration in the processing of filler-gap dependencies: an ERP study of topicalization and wh-movement in German

We recorded event-related brain potentials (ERPs) during the processing of unambiguous German sentences containing different types of filler-gap dependency. Both topicalization constructions and wh-questions were found to elicit a left-anterior negativity (LAN) prior to the processing of the subcategorizing verb, relative to a gap-free control condition. At the subcategorizing verb, sentences containing a wh-dependency produced a parietal positivity (P600) relative to topicalization structures. These results support the claim that separable parsing processes are involved in the processing of syntactic dependencies, with working memory based processes being reflected in an LAN, and the relative difficulty of integrating the filler with its subcategorizer reflected in a P600. Integration cost but not memory cost was found to be influenced by the type of filler-gap dependency involved.     

In Defense of Competition During Syntactic Ambiguity Resolution

In a recent series of publications (Traxler et al. J Mem Lang 39:558–92, 1998; Van Gompel et al. J Mem Lang 52:284–07, 2005; see also Van Gompel et al. (In: Kennedy, et al.(eds) Reading as a perceptual process, Oxford, Elsevier pp 621–48, 2000); Van Gompel et al. J Mem Lang 45:225–58, 2001) eye tracking data are reported showing that globally ambiguous (GA) sentences are read faster than locally ambiguous (LA) counterparts. They argue that these data rule out ‘constraint-based’models where syntactic and conceptual processors operate concurrently and syntactic ambiguity resolution is accomplished by competition. Such models predict the opposite pattern of reading times. However, this argument against competition is valid only in conjunction with two standard assumptions in current constraint-based models of sentence comprehension: (1) that syntactic competitions (e.g., Which is the best attachment site of the incoming constituent?) are pooled together with conceptual competitions (e.g., Which attachment site entails the most plausible meaning?), and (2) that the duration of a competition is a function of the overall (pooled) quality score obtained by each competitor. We argue that it is not necessary to abandon competition as a successful basis for explaining parsing phenomena and that the above-mentioned reading time data can be accounted for by a parallel-interactive model with conceptual and syntactic processors that do not pool their quality scores together. Within the individual linguistic modules, decision-making can very well be competition-based.     

Comprehension of Ambiguous Sentences in Non-Disabled and Disabled Adolescents

If students are to effectively comprehend a text, they must be able to resolve ambiguities. Recent studies of adolescents with learning disabilities suggest multiple reasons for failure to resolve ambiguous structures. Furthermore, previous research does not clearly indicate the age at which syntactic ambiguities can be resolved consistently. The present study investigated similarities and differences in the comprehension of ambiguous sentences in adolescents with and without learning disabilities. Four groups representing four ability levels were sampled in a public high schools. Two additional groups of students with learning disabilities were sampled at a private residential school. The public school group that attained academic honors was superior to all other groups in paraphrasing the meanings of ambiguous sentences. Two other college bound public school groups were superior to a non-college bound group in the public system. These findings suggest a continuum of ability to interpret amiguous structures across a range of 16 year old subjects. The learning disabled private school group with stronger verbal than non-verbal abilities was also significantly better than the non-college bound disabled public school gorup. This superiority of the learning disabled over the non-college bound group suggest a continuum of ability to interpret ambiguous structures in a population of students with various disabilites. The study found associations between knowledge of syntax and knowledge of lexical meaning and interpretation of ambigous materials. There also was a strong relationships between the ability to paraphrase the meanings of ambiguous sentences and overall ability in reading comprehension.     

句法预测对句子理解影响的眼动实验

实验采用眼动技术实时考察了句子阅读理解过程中的句法预测效应和并列句的结构表征特点。眼动数据分析发现：(1)有无句法预测没有明显影响名词短语区域的加工, 不同眼动指标差异不显著; (2)有无句法预测显著影响被试对包含暂时局部歧义的关键区和具有解歧作用的关键后区域的阅读理解, 首次注视时间、第一遍阅读时间、回视路径时间和第一遍回视率明显减少。眼动研究表明, 暂时局部歧义句子阅读理解过程中表现出明显的句法预测效应, 有句法预测降低了局部歧义区域和解歧区域早期和晚期加工的难度; 和英语的短语并列优先法则不同, 汉语并列句子的结构表征出现分离现象, 即短语并列和句子并列。     

The influence of prosodic structure on the resolution of temporary syntactic closure ambiguities

This paper investigates the influence of prosodic structure on the process of sentence comprehension, with a specific focus on the relative contributions of syntactic and prosodic information to the resolution of temporary syntactic closure ambiguities. We argue that prosodic structure provides an initial memory representation for spoken sentences, and that information from this prosodic representation is available to inform syntactic parsing decisions. This view makes three predictions for the processing of temporary syntactic ambiguity: 1. When prosodic and syntactic boundaries coincide, syntactic processing should be facilitated. 2. When prosodic boundaries are placed at misleading points in syntactic structure, syntactic processing should show interference effects. 3. The processing difficulties that have been reliably demonstrated in reading experiments for syntactically complex sentences should disappear when those sentences are presented with a felicitous prosodic structure in listening experiments. These predictions were confirmed by series of experiments measuring end-of-sentence comprehension time and cross-modal naming time for sentences with temporary syntactic closure ambiguities. Sentences with coinciding or conflicting prosodic and syntactic boundaries were compared to a prosodic baseline condition.This research was supported in part by NIMH grant R29 MH51768 to the first author and NIMH grant T32 MH19729 to the Northeastern University Psychology Department.     

The brain basis of the phonological deficit in dyslexia is independent of IQ

Although the role of IQ in developmental dyslexia remains ambiguous, the dominant clinical and research approaches rely on a definition of dyslexia that requires reading skill to be significantly below the level expected given an individual's IQ. In the study reported here, we used functional MRI (fMRI) to examine whether differences in brain activation during phonological processing that are characteristic of dyslexia were similar or dissimilar in children with poor reading ability who had high IQ scores (discrepant readers) and in children with poor reading ability who had low IQ scores (nondiscrepant readers). In two independent samples including a total of 131 children, using univariate and multivariate pattern analyses, we found that discrepant and nondiscrepant poor readers exhibited similar patterns of reduced activation in brain areas such as left parietotemporal and occipitotemporal regions. These results converge with behavioral evidence indicating that, regardless of IQ, poor readers have similar kinds of reading difficulties in relation to phonological processing.     

Falsifying Serial and Parallel Parsing Models: Empirical Conundrums and An Overlooked Paradigm

When the human parser encounters a local structural ambiguity, are multiple structures pursued (parallel or breadth-first parsing), or just a single preferred structure (serial or depth-first parsing)? This note discusses four important classes of serial and parallel models: simple limited parallel, ranked limited parallel, deterministic serial with reanalysis, and probabilistic serial with reanalysis. It is argued that existing evidence is compatible only with probabilistic serial-reanalysis models, or ranked parallel models augmented with a reanalysis component. A new class of linguistic structures is introduced on which the behavior of serial and parallel parsers diverge the most radically: multiple local ambiguities are stacked to increase the number of viable alternatives in the ambiguous region from two to eight structures. This paradigm may provide the strongest test yet for parallel models.     

An event-related fMRI study of syntactic and semantic violations

We used event-related functional magnetic resonance imaging to identify brain regions involved in syntactic and semantic processing. Healthy adult males read well-formed sentences randomly intermixed with sentences which either contained violations of syntactic structure or were semantically implausible. Reading anomalous sentences, as compared to well-formed sentences, yielded distinct patterns of activation for the two violation types. Syntactic violations elicited significantly greater activation than semantic violations primarily in superior frontal cortex. Semantically incongruent sentences elicited greater activation than syntactic violations in the left hippocampal and parahippocampal gyri, the angular gyri bilaterally, the right middle temporal gyrus, and the left inferior frontal sulcus. These results demonstrate that syntactic and semantic processing result in nonidentical patterns of activation, including greater frontal engagement during syntactic processing and larger increases in temporal and temporo-parietal regions during semantic analyses.     

Some observations on the universality of the late-closure strategy

Two questionnaire studies and a reading time experiment investigated the application of the late-closure principle in Italian, a Romance language which contrasts with English with respect to several linguistic properties. All the studies addressed interpretation preferences in sentences containing a complex NP followed by a relative clause (e.g....the son of the woman who arrived yesterday...). While the questionnaires investigated final preferences, the reading time experiment addressed also the principle governing the initial attachment of a relative clause to a complex NP. Furthermore, through a manipulation of the type of preposition within the complex NP, we investigated the role of the thematic structure of the complex NP in initial and final parsing. The results showed that the late-closure principle applies in Italian to the initial parsing without being affected by the thematic structure of the complex NP. Final interpretation instead shows an effect of pragmatic preference and an effect of thematic structure on syntactic revisions. The results are discussed in terms of a parsing model that adopts syntactic parsing strategies and makes modular use of linguistic information. Some implications for the relationship between syntactic theories and the human parser are also addressed.     

Children’s (in)ability to recover from garden paths in a verb-final language: Evidence for developing control in sentence processing

An eye-tracking study explored Korean-speaking adults’ and 4- and 5-year-olds’ ability to recover from misinterpretations of temporarily ambiguous phrases during spoken language comprehension. Eye movement and action data indicated that children, but not adults, had difficulty in recovering from these misinterpretations despite strong disambiguating evidence at the end of the sentence. These findings are notable for their striking similarities with findings from children parsing English; however, in those and other studies of English, children were found to be reluctant to use late-arriving syntactic evidence to override earlier verb-based cues to structure, whereas here Korean children were reluctant to use late-arriving verb-based cues to override earlier syntactic evidence. The findings implicate a general cross-linguistic pattern for parsing development in which late-developing cognitive control abilities mediate the recovery from so-called “garden path” sentences. Children’s limited cognitive control prevents them from inhibiting misinterpretations even when the disambiguating evidence comes from highly informative verb information.