Veena D. Dwivedi

Syntactic Processing by Skilled Bilinguals

Recent advances in cross-language psycholinguistics provide reading researchers with both the models and the tools needed to investigate the syntactic processing of second language (L2) readers. In our study, 48 L1 (first language) and 48 highly fluent L2 French readers read sentences containing constructions that do not exist in English, the L1 of the L2 readers: pre-verbal pronominalization (clitics) and the faire+infinitive causative construction. The L2 readers exhibited the same processing as L1 French readers; however, slower (but equally fluent) L2 readers also employed a compensatory processing for sentences with clitics. These results build on previous findings that faster L2 readers are more efficient in their use of lower-level information by demonstrating that they are also more efficient at higher-level syntactic processing. Results are discussed in terms of implications for theories of L2 reading and recent models of cross-language syntactic processing.

Sensitivity to prosodic structure in left- and right-hemisphere-damaged individuals

An experiment was conducted in order to determine whether left- (LHD) and right-hemisphere-damaged (RHD) patients exhibit sensitivity to prosodic information that is used in syntactic disambiguation. Following the work of, a cross-modal lexical decision task was performed by LHD and RHD subjects, as well as by adults without brain pathology (NC). Subjects listened to sentences with attachment ambiguities with either congruent or incongruent prosody, while performing a visual lexical decision task. Results showed that each of the unilaterally damaged populations differed from each other, as well as from the NCs in terms of sensitivity regarding prosodic cues. Specifically, the RHD group was insensitive to sentence prosody as a whole. This was in contrast to the LHD patients, who responded to the prosodic manipulation, but in the unexpected direction. Results are discussed in terms of current hypotheses regarding the hemispheric lateralization of prosodic cues.

The neural underpinnings of semantic ambiguity and anaphora

We used event-related brain potentials (ERPs) in order to investigate how definite NP anaphors are integrated into semantically ambiguous contexts. Although sentences such as Every kid climbed a tree lack any syntactic or lexical ambiguity, these structures exhibit two possible meanings, where either many trees or only one tree was climbed. This semantic ambiguity is the result of quantifier scope ambiguity. Previous behavioural studies have shown that a plural definite NP continuation is preferred (as reflected in a continuation sentence, e.g., The trees were in the park) over singular NPs (e.g., The tree was in the park). This study aimed to identify the neurophysiological pattern associated with the integration of the continuation sentences, as well as the time course of this process. We examined ERPs elicited by the noun and verb in continuation sentences following ambiguous and unambiguous context sentences. A sustained negative shift was most evident at the Verb position in sentences exhibiting scope ambiguity. Furthermore, this waveform did not differentiate itself until 900 ms after the presentation of the Noun, suggesting that the parser waits to assign meaning in contexts exhibiting quantifier scope ambiguity, such that such contexts are left as underspecified representations.

Interpreting Quantifier Scope Ambiguity: Evidence of Heuristic First, Algorithmic Second Processing

The present work suggests that sentence processing requires both heuristic and algorithmic processing streams, where the heuristic processing strategy precedes the algorithmic phase. This conclusion is based on three self-paced reading experiments in which the processing of two-sentence discourses was investigated, where context sentences exhibited quantifier scope ambiguity. Experiment 1 demonstrates that such sentences are processed in a shallow manner. Experiment 2 uses the same stimuli as Experiment 1 but adds questions to ensure deeper processing. Results indicate that reading times are consistent with a lexical-pragmatic interpretation of number associated with context sentences, but responses to questions are consistent with the algorithmic computation of quantifier scope. Experiment 3 shows the same pattern of results as Experiment 2, despite using stimuli with different lexical-pragmatic biases. These effects suggest that language processing can be superficial, and that deeper processing, which is sensitive to structure, only occurs if required. Implications for recent studies of quantifier scope ambiguity are discussed.

ERPs reveal sensitivity to hypothetical contexts in spoken discourse.

We used event-related potentials to examine the interaction between two dimensions of discourse comprehension: (i) referential dependencies across sentences (e.g. between the pronoun ‘it’ and its antecedent ‘a novel’ in: ‘John is reading a novel. It ends quite abruptly’), and (ii) the distinction between reference to events/situations and entities/individuals in the real/actual world versus in hypothetical possible worlds. Cross-sentential referential dependencies are disrupted when the antecedent for a pronoun is embedded in a sentence introducing hypothetical entities (e.g. ‘John is considering writing a novel. It ends quite abruptly’). An earlier event-related potential reading study showed such disruptions yielded a P600-like frontal positivity. Here we replicate this effect using auditorily presented sentences and discuss the implications for our understanding of discourse-level language processing.

The Neuronal Correlates of Indeterminate Sentence Comprehension: An fMRI Study

Sentences such as The author started the book are indeterminate because they do not make explicit what the subject (the author) started doing with the object (the book). In principle, indeterminate sentences allow for an infinite number of interpretations. One theory, however, assumes that these sentences are resolved by semantic coercion, a linguistic process that forces the noun book to be interpreted as an activity (e.g., writing the book) or by a process that interpolates this activity information in the resulting enriched semantic composition. An alternative theory, pragmatic, assumes classical semantic composition, whereby meaning arises from the denotation of words and how they are combined syntactically, with enrichment obtained via pragmatic inferences beyond linguistic-semantic processes. Cognitive neuroscience studies investigating the neuroanatomical and functional correlates of indeterminate sentences have shown activations either at the ventromedial pre-frontal cortex (vmPFC) or at the left inferior frontal gyrus (L-IFG). These studies have supported the semantic coercion theory assuming that one of these regions is where enriched semantic composition takes place. Employing functional magnetic resonance imaging (fMRI), we found that indeterminate sentences activate bilaterally the superior temporal gyrus (STG), the right inferior frontal gyrus (R-IFG), and the anterior cingulate cortex (ACC), more so than control sentences (The author wrote the book). Activation of indeterminate sentences exceeded that of anomalous sentences (…drank the book) and engaged more left- and right-hemisphere areas than other sentence types. We suggest that the widespread activations for indeterminate sentences represent the deployment of pragmatic-inferential processes, which seek to enrich sentence content without necessarily resorting to semantic coercion.