Verbal working memory and sentence comprehension

This target article discusses the verbal working memory system used in sentence comprehension. We review the concept of working memory as a short-duration system in which small amounts of information are simultaneously stored and manipulated in the service of accomplishing a task. We summarize the argument that syntactic processing in sentence comprehension requires such a storage and computational system. We then ask whether the working memory system used in syntactic processing is the same as that used in verbally mediated tasks that involve conscious controlled processing. Evidence is brought to bear from various sources: the relationship between individual differences in working memory and individual differences in the efficiency of syntactic processing; the effect of concurrent verbal memory load on syntactic processing; and syntactic processing in patients with poor short-term memory, patients with poor working memory, and patients with aphasia. Experimental results from these normal subjects and patients with various brain lesions converge on the conclusion that there is a specialization in the verbal working memory system for assigning the syntactic structure of a sentence and using that structure in determining sentence meaning that is separate from the working memory system underlying the use of sentence meaning to accomplish other functions. We present a theory of the divisions of the verbal working memory system and suggestions regarding its neural basis.     

Interactive processes in sentence comprehension and recognition

Two experiments examined the roles played by semantic and surface information in reading and recognizing sentences. Subjects read sentences in normal and inverted typography. Their recognition of meaning and other sentence features was tested using sentences whose typography, wording, and/or meaning were either the same as or different from that in the first set of sentences. In Experiment 1, subjects either read aloud or performed a sentence continuation task. For originally inverted sentences, recognition of meaning was high, irrespective of task demands. For originally normal sentences, recognition was low for Read Aloud subjects and high for Sentence Continuation subjects. Sentence recognition was affected by repetition of wording and typography. Experiment 2 replicated the results with the read aloud task and showed the second reading of originally inverted sentences to be equally swift for paraphrase and verbatim test forms. It was concluded that reading and recognition are interactive processes, involving conceptually driven and data driven operations. The interaction of operations may be either automatic or controlled. While processing of normal typography is automatic, inverted typography induces controlled processing, resulting in better retention. Furthermore, semantic and surface information are conceptualized as interacting components of comprehension and memory processes.     

Computational principles of working memory in sentence comprehension

Understanding a sentence requires a working memory of the partial products of comprehension, so that linguistic relations between temporally distal parts of the sentence can be rapidly computed. We describe an emerging theoretical framework for this working memory system that incorporates several independently motivated principles of memory: a sharply limited attentional focus, rapid retrieval of item (but not order) information subject to interference from similar items, and activation decay (forgetting over time). A computational model embodying these principles provides an explanation of the functional capacities and severe limitations of human processing, as well as accounts of reading times. The broad implication is that the detailed nature of cross-linguistic sentence processing emerges from the interaction of general principles of human memory with the specialized task of language comprehension.     

Storage and retrieval processes in sentence memory

Two experiments investigated how much time Ss take to verify a sentence with respect to a set of subject-verb-object (SVO) propositions they had learned. Three triplets of SVOs provided differing degrees of equivocation, including (1) unique SVOs, (2) a V with 3 SOs, and (3) an SV with 3 Os. A general class of models was proposed regarding the representation of prepositional trees in memory and an algorithm by which a probe tree might be verified against a set of trees in memory. In Expt I, verification times were least for Condition (1), slower and equal for Conditions (2) and (3). In Expt II, a fourth condition, an SO with 3 Vs, produced verification times as slow as those in Condition (3). Of several models considered, the closest-fitting one assumed parallel search processes proceeding simultaneously from S, V, and O positions of the probe, scanning through memory trees structered according to the HAM (Human Associative Memory) theory of Anderson and Bower.     

Spatial and linguistic aspects of visual imagery in sentence comprehension

There is mounting evidence that language comprehension involves the activation of mental imagery of the content of utterances ( Barsalou, 1999 ; Bergen, Chang, & Narayan, 2004 ; Bergen, Narayan, & Feldman, 2003 ; Narayan, Bergen, & Weinberg, 2004 ; Richardson, Spivey, McRae, & Barsalou, 2003 ; Stanfield & Zwaan, 2001 ; Zwaan, Stanfield, & Yaxley, 2002 ). This imagery can have motor or perceptual content. Three main questions about the process remain under‐explored, however. First, are lexical associations with perception or motion sufficient to yield mental simulation, or is the integration of lexical semantics into larger structures, like sentences, necessary? Second, what linguistic elements (e.g., verbs, nouns, etc.) trigger mental simulations? Third, how detailed are the visual simulations that are performed? A series of behavioral experiments address these questions, using a visual object categorization task to investigate whether up‐ or down‐related language selectively interferes with visual processing in the same part of the visual field (following Richardson et al., 2003 ). The results demonstrate that either subject nouns or main verbs can trigger visual imagery, but only when used in literal sentences about real space—metaphorical language does not yield significant effects—which implies that it is the comprehension of the sentence as a whole and not simply lexical associations that yields imagery effects. These studies also show that the evoked imagery contains detail as to the part of the visual field where the described scene would take place.     

Conceptual combination during sentence comprehension: evidence for compositional processes

This experiment examined the time course of integration of modifier-noun (conceptual) combinations during auditory sentence comprehension using cross-modal lexical priming. The study revealed that during ongoing comprehension, there is initial activation of features of the noun prior to activation of (emergent) features of the entire conceptual combination. These results support compositionality in conceptual combination; that is, they indicate that features of the individual words constituting a conceptual combination are activated prior to combination of the words into a new concept.     

The role of working memory in inferential sentence comprehension

Existing literature on inference making is large and varied. Trabasso and Magliano (Discourse Process 21(3):255–287, 1996) proposed the existence of three types of inferences: explicative, associative and predictive. In addition, the authors suggested that these inferences were related to working memory (WM). In the present experiment, we investigated whether WM capacity plays a role in our ability to answer comprehension sentences that require text information based on these types of inferences. Participants with high and low WM span read two narratives with four paragraphs each. After each paragraph was read, they were presented with four true/false comprehension sentences. One required verbatim information and the other three implied explicative, associative and predictive inferential information. Results demonstrated that only the explicative and predictive comprehension sentences required WM: participants with high verbal WM were more accurate in giving explanations and also faster at making predictions relative to participants with low verbal WM span; in contrast, no WM differences were found in the associative comprehension sentences. These results are interpreted in terms of the causal nature underlying these types of inferences.     

Test anxiety,sentence comprehension,and recognition memory

Abstract

The present study explored the relationships between trait and state test anxiety of students, and comprehension and recognition memory for sentences. The results demonstrated that test anxiety effects could be found in comprehension-based recognition memory for sentences under conditions that minimized complex retrieval operations. Comprehension was related to the test anxiety deficit, supporting the hypothesis that anxiety-recognition relations were mediated by anxiety-comprehension and comprehension-recognition relations. However, a partial correlation analysis suggested that this comprehension-deficit hypothesis is not adequate to explain the total deficit. Elaborative processes were suggested as a potential contributor to the findings.     

The time-course of lexical and structural processes in sentence comprehension

Online sentence comprehension involves multiple types of cognitive processes: lexical processes such as lexical access, which call on the user's knowledge of the meaning of words in the language, and structural processes such as the integration of incoming words into an emerging representation. In this article, we investigate the temporal dynamics of lexical access and syntactic integration. Unlike much previous work that has relied on temporary ambiguity to investigate this question, we manipulate the frequency of the verb in unambiguous structures involving a well-studied syntactic complexity manipulation (subject- vs. object-extracted clefts). The results demonstrate that for high-frequency verbs, the difficulty of reading a more structurally complex object-extracted cleft structure relative to a less structurally complex subject-extracted cleft structure is largely experienced in the cleft region, whereas for low-frequency verbs this difficulty is largely experienced in the postcleft region. We interpret these results as evidence that some stages of structural processing follow lexical processing. Furthermore, we find evidence that structural processing may be delayed if lexical processing is costly, and that the delay is proportional to the difficulty of the lexical process. Implications of these results for contemporary accounts of sentence comprehension are discussed.     

Decision processes during sentence comprehension: Effects of surface structure reconsidered

Previous experiments have yielded conflicting results concerning the utility of relative pronouns as cues to the deep structure underlying self-embedded (SE) sentences. The present study investigated the usefulness of this cue. At the same time, it compared the relative sensitivity of two measures of sentence-comprehension difficulty: paraphrasing and phoneme monitoring. Forty Ss heard SE sentences, one-half of which had the relative pronouns deleted. The presence or absence of the relative pronouns in a particular sentence was counterbalanced across groups. The Ss also heard right-branching sentences. It was found that presence of the relative pronouns led to significantly faster phoneme monitoring times and to marginally better paraphrasing (i.e., to better comprehension) in the SE sentences. It was concluded that relative pronouns are effective cues and, further, that the phoneme monitoring technique is a better index of comprehension difficulty than the paraphrasing technique. Reasons for the previous experimental discrepancies were discussed.     

The effects of metaphorical and literal comprehension processes on lexical decision latency of sentence components

Two lexical decision experiments were conducted to further investigate the notion that metaphor comprehension involves the formation of a new association between topic and vehicle. Experiment 1 was essentially a replication and extension of Camac and Glucksberg (1984) demonstrating that known word associate pairs show a significant lexical decision latency advantage over their randomly paired counterparts, while topic/vehicle word pairs drawn from apt metaphors do not. The results of Experiment 1 confirm their initial findings even when printed word frequency of the two pair types is held equivalent (a factor not controlled for in the original Camac and Glucksberg study). This result suggests that preexisting topic/vehicle similarity is not an important factor in metaphor comprehension. Experiment 2 was an attempt to detect the hypothesized shift in attribute salience that results in the formation of a new association between topic and vehicle during metaphor comprehension. In Experiment 2, subjects made lexical decisions on topic/vehicle word pairs that were preceded by a paragraph designed to induce either a metaphorical or literal interpretation. For many subjects, a latency advantage was observed for topic/vehicle pairs preceded by a metaphorical context as compared to a mismatching literal context. This finding suggests that metaphor comprehension is a dynamic process which modifies preexisting topic/vehicle similarity, and that metaphorical interpretations are facilitated by extended context.Portions of this paper were submitted to the Department of Psychology, Iowa State University, in partial fulfillment of the requirements for the Doctor of Philosophy degree. Special thanks to Dr. Veronica J. Dark for her comments on theoretical aspects of this work, as well as her assistance with the use of microcomputers for the collection and analysis of data. The feedback provided by Thomas Andre, Lloyd L. Avant, Harry S. Gill, Donald H. Schuster, and Horabail, Venkatagiri is greatly appreciated.     

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.     

Working memory and updating processes in reading comprehension

In this study, we examine the relation between reading comprehension ability and success in working memory updating tasks. Groups of poor and good comprehenders, matched for logical reasoning ability, but different in reading comprehension ability, were administered various updating tasks in a series of experiments. In the first experiment, the participants were presented with lists of words, the length of which (4-10 words) was unknown beforehand, and were required to remember the last 4 words in each series. In this task, we found a decrease in performance that was related to longer series and poor reading ability. In the second experiment, we presented lists of nouns referring to items of different sizes, in a task that simulated the selection and updating of relevant information that occurs in the on-line comprehension process. The participants were required to remember a limited, predefined number of the smallest items presented. We found that poor comprehenders not only had a poorer memory, but also made a greater number of intrusion errors. In the third and fourth experiments, memory load (number of items to be selected) and suppression request (number of potentially relevant items) were manipulated within subjects. Increases in both memory load and suppression requests impaired performance. Furthermore, we found that poor comprehenders produced a greater number of intrusion errors, particularly when the suppression request was increased. Finally, in a fifth experiment, a request to specify the size of presented items was introduced. Poor comprehenders were able to select the appropriate items, although their recall was poorer. Altogether, the data show that working memory abilities, based on selecting and updating relevant information and avoiding intrusion errors, are related to reading comprehension.     

Age, working memory, and on-line syntactic processing in sentence comprehension

One hundred twenty-seven individuals who ranged in age from 18 to 90 years were tested on a reading span test and on measures of on-line and off-line sentence processing efficiency. Older participants had reduced working-memory spans compared with younger participants. The on-line measures were sensitive to local increases in processing load, and the off-line measures were sensitive to the syntactic complexity of the sentences. Older and younger participants showed similar effects of syntactic complexity on the on-line measures. There was some evidence that older participants were more affected than younger participants by syntactic complexity on the off-line measures. The results support the hypothesis that on-line processes involved in recognizing linguistic forms and determining the literal, preferred, discourse-coherent meaning of sentences constitute a domain of language processing that relies on its own processing resource or working-memory system.     

In search of on-line locality effects in sentence comprehension

Many comprehension theories assert that increasing the distance between elements participating in a linguistic relation (e.g., a verb and a noun phrase argument) increases the difficulty of establishing that relation during on-line comprehension. Such locality effects are expected to increase reading times and are thought to reveal properties and limitations of the short-term memory system that supports comprehension. Despite their theoretical importance and putative ubiquity, however, evidence for on-line locality effects is quite narrow linguistically and methodologically: It is restricted almost exclusively to self-paced reading of complex structures involving a particular class of syntactic relation. We present 4 experiments (2 self-paced reading and 2 eyetracking experiments) that demonstrate locality effects in the course of establishing subject-verb dependencies; locality effects are seen even in materials that can be read quickly and easily. These locality effects are observable in the earliest possible eye-movement measures and are of much shorter duration than previously reported effects. To account for the observed empirical patterns, we outline a processing model of the adaptive control of button pressing and eye movements. This model makes progress toward the goal of eliminating linking assumptions between memory constructs and empirical measures in favor of explicit theories of the coordinated control of motor responses and parsing.     

The allocation of memory resources during sentence comprehension: Evidence from the elderly

Two experiments were carried out to examine the ability of elderly subjects to establish syntactically governed dependency relations during the course of sentence comprehension. The findings reveal the manner in which memory constraints operate during syntactic processing.     

Context effects in sentence comprehension: A study of the subjective lexicon

These studies explore the role of context in determining what information about the meanings of words is activated in memory at the time a word is encountered in a sentence. Using a color-naming paradigm, it was shown that both meanings of a word that has two distinct meanings are activated in memory at the time the word is heard in a sentence. This activation occurs even when there is sufficient contextual information to indicate which meaning was intended by the speaker. These results support the hypothesis that there exists in memory an isolable subjective lexicon. They suggest that context which is effective in disambiguating lexical ambiguities in the language has its effect only at a relatively late stage in the cognitive processing involved in language comprehension.     

Syntactic presupposition in sentence comprehension

Two experiments investigated the role of syntactic presupposition in sentence comprehension. In Experiment I subjects verified cleft, pseudocleft and factive complement sentences with respect to preceding context paragraphs, which contradicted either the assertion or the presupposition of the target sentence. Subjects took significantly longer to verify sentences with false presuppositions than sentences with false assertions. In Experiment II subjects verified cleft and pseudocleft sentences with respect to subsequently presented pictures. Once again, verification times for sentences with false presuppositions were significantly longer than verification times for sentences with false assertions. It was argued that these findings are more adequately explained by a “structural” hypothesis, than in terms of strategies designed to locate given and new information.     

Processing strategies in sentence comprehension

Response latencies in sentence-picture verification tasks were compared as a function of whether a mismatch was located in the logical subject (LS), verb (V), or logical object (LO) of the sentence. Sentences were presented auditorily and varied in voice and reversibility. The comparison process for nonreversibles was clearly serial self-terminating: latencies for both actives and passives were ordered LS < V < LO, or, after practice with a small number of mismatch types, LS < LO < V. Latencies for reversibles were ordered V < LS = LO, suggesting either a verb-first comparison process or an LS-V-LO comparison process which did not terminate with a subject-mismatch because of the confusability of the subject and object. The results attest to the importance of considering the "naturalness" of stimuli in sentence processing tasks, and the flexibility of subjects' encoding and comparison strategies both within and across task contexts.     

Lexical information in sentence comprehension

An experiment was constructed testing predictions derived from the mental model theory. According to this theory, individual words in a sentence provide clues to the building of the mental model of the sentence and need to be interpreted in relation to general knowledge of situations similar to those described in the sentence. After reading a sentence, subjects had to produce, as quickly as possible, one aspect of the meaning of a target noun. The sentence either did or did not contain the target noun, and it primed either one aspect of its meaning or no specific aspect of it. The prediction was that the subjects would be faster and more uniform at producing the primed aspect of the target noun after a priming sentence than at producing any aspect of the noun after a non-priming sentence, and this difference would occur regardless of whether the target noun had occurred in the prior sentence. The results, which confirm the predictions, are discussed in relation to current theories of sentence comprehension.