Randall Hendrick

Memory interference during language processing.

The authors studied the operation of working memory in language comprehension by examining the reading of complex sentences. Reading time and comprehension accuracy in self-paced reading by college students were studied as a function of type of embedded clause (object-extracted vs. subject-extracted) and the types of noun phrases (NPs) in the stimulus sentences, including relative clauses and clefts. The poorer language comprehension performance typically observed for object-extracted compared with subject-extracted forms was found to depend strongly on the mixture of types of NPs (descriptions, indexical pronouns, and names) in a sentence. Having two NPs of the same type led to a larger performance difference than having two NPs of a different type. The findings support a conception of working memory in which similarity-based interference plays an important role in sentence complexity effects.

Memory-Load Interference in Syntactic Processing

Participants remembered a short set of words while reading syntactically complex sentences (object-extracted clefts) and syntactically simpler sentences (subject-extracted clefts) in a memory-load study. The study also manipulated whether the words in the set and the words in the sentence were of matched or unmatched types (common nouns vs. proper names). Performance in sentence comprehension was worse for complex sentences than for simpler sentences, and this effect was greater when the type of words in the memory load matched the type of words in the sentence. These results indicate that syntactic processing is not modular, instead suggesting that it relies on working memory resources that are used for other nonsyntactic processes. Further, the results indicate that similarity-based interference is an important constraint on information processing that can be overcome to some degree during language comprehension by using the coherence of language to construct integrated representations of meaning.

The representation and processing of coreference in discourse

A model is presented that addresses both the distribution and comprehension of different forms of referring expressions in language. This model is expressed in a formalism (Kamp & Reyle, 1993) that uses interpretive rules to map syntactic representations onto representations of discourse. Basic interpretive rules are developed for names, pronouns, definite descriptions, and quantified descriptions. These rules are triggered by syntactic input and interact dynamically with representations of discourse to establish reference and coreference. This interaction determines the ease with which coreference can be established for different linguistic forms given the existing discourse context. The performance of the model approximates that observed in studies of intuitive judgments of grammaticality and studies using online measures of language comprehension. The model uses the same basic interpretive mechanisms for coreference within and between sentences, thereby linking the domain traditionally studied by generative linguists to domains that have been of concern primarily to psychologists and computational linguists.

Similarity-Based Interference During Language Comprehension: Evidence from Eye Tracking During Reading

The nature of working memory operation during complex sentence comprehension was studied by means of eye-tracking methodology. Readers had difficulty when the syntax of a sentence required them to hold 2 similar noun phrases (NPs) in working memory before syntactically and semantically integrating either of the NPs with a verb. In sentence structures that placed these NPs at the same linear distances from one another but allowed integration with a verb for 1 of the NPs, the comprehension difficulty was not seen. These results are interpreted as indicating that similarity-based interference occurs online during the comprehension of complex sentences and that the degree of memory accessibility conventionally associated with different types of NPs does not have a strong effect on sentence processing.

Processing of Reference and the Structure of Language: An Analysis of Complex Noun Phrases

Five experiments used self-paced reading time to examine the ways in which complex noun phrases (both conjoined NPs and possessive NPs) influence the interpretation of referentially dependent expressions. The experimental conditions contrasted the reading of repeated names and pronouns referring to components of a complex NP and to the entire complex NP. The results indicate that the entity introduced by a major constituent of a sentence is more accessible as a referent than the entities introduced by component noun phrases. This pattern of accessibility departs from the advantage of first mention that has been demonstrated using probe-word recognition tasks. It supports the idea that reduced expressions are interpreted as referring directly to prominent entities in a mental model whereas reference by names to entities that are already represented in a mental model is mediated by additional processes. The same interpretive processes appear to operate on coreference within and between sentences.

Language comprehension and probe-list memory.

Experiments were performed using probe-word recognition methodology in which participants read sentences that were presented 1 word at a time and were then shown a probe word and had to make a speeded response indicating whether the word had occurred in the sentence. One experiment showed that response times to probe words increased with the size of the set of candidate probes. The other experiments showed that the effects caused by name repetition in circumstances in which the repeated name was co-referential also occurred when the repeated name was not co-referential and when the order of words in a sentence was scrambled. The results suggest that responses in the task can be based on probe-list memory, a mental representation created to keep track of those words that the participant believes are likely to be probed, and that the use of the task to make inferences about language comprehension should be accompanied by controls ruling out such strategies.

Comprehension of Referring Expressions in Chinese

Studies of English have shown that reduced referential expressions (e.g. pronouns) contribute more to discourse coherence than do unreduced expressions (e.g. proper names). To test the generality of these findings, a series of reading-time studies was conducted to examine the processing of coreference in Chinese discourse. The results obtained for Chinese were similar to those obtained previously for English. Furthermore, comparisons of the comprehension of overt pronouns and zero pronouns (a phologically-null form not present in English) showed that the two types of reduced referring expressions contribute equally to discourse coherence for the kinds of passages studied in the experiments. A formal model of the structure and processing of reference in discourse, developed to handle co-reference phenomena in English, is shown to provide an account of these experimental results on the reading of Chinese.

Constraining the comprehension of pronominal expressions in Chinese

This paper reports a series of self-paced reading time experiments designed to probe how the reference of pronominal expressions is resolved on-line in (Mandarin) Chinese. It is assumed that pronoun resolution is achieved by narrowing the candidate set of potential antecedents for a pronoun. The experimental evidence reported here indicates that two factors--syntactic prominence and the matching of lexical features (e.g. gender)--play a significant role in filtering this candidate set. It is shown that syntactic prominence and feature matching work in conjunction with each other rather than in a competitive, winner-take-all manner. Furthermore, the evidence suggests that syntactic prominence is sensitive to structural relations rather than exclusively to grammatical functions (such as subject and direct object) or semantic roles (such as agent and patient) as has been assumed in the psycholinguistic literature.

Relativization, Ergativity, and Corpus Frequency

RELATIVIZATION, ERGATIVITY, AND CORPUS FREQUENCY Peter C. Gordon University of North Carolina Randall Hendrick University of North Carolina It is common to distinguish ergative languages from accusative languages. Whether this distinction is a surface morphological one or reflects a deeper division in how semantic composition is done has been the subject of debate (see Manning 1999 for a detailed overview). Ergative languages appear unusual because they are infrequent crosslinguistically. This view is corroborated by the fact that most ergative languages exhibit split ergative systems in which the ergative casemarking system holds in some structural contexts but the accusative emerges in others (Dixon 1979). In contrast, accusative languages typically lack ergative features. For this reason, some work has been done on how ergative languages could arise historically from accusative systems (see Trask 1979, Anderson 1976, Garrett 1990). There is a tradition of thought in functional linguistics that offers a different view of the distinction between ergative and accusative languages. Fox (1987), for example, conjectures that ergativity is a highly natural feature of language and can be seen in common patterns of relativization. Specifically, Fox proposes the Absolutive Hypothesis (AH) in (1).

The Processing of Coreference for Reduced Expressions in Discourse Integration

Three reading-time experiments in Chinese are reported that test contrasting views of how pronominal coreference is achieved. On the one hand, studies of reading time and eye tracking suggest that reduced expressions, such as the pronoun he, serve as critical links to integrate separate utterances into a coherent model of discourse. On the other hand, probe-word recognition studies indicate that full anaphoric expressions, such as a repeated name, are more readily interpreted than reduced expressions due to their rich lexical information, which provides effective cues to match the representation of the appropriate referent in memory. The results indicate that the ease of integrating the critical referent into a model of discourse is a function of the congruence of lexical, semantic, and discourse features conveyed by a syntactically prominent reduced expression within linguistic input. This pattern supports the view that a reduced expression is interpreted on-line and indeed plays a critical role in promoting discourse coherence by facilitating the semantic integration of separate utterances.