Brian McElree - US grants

DESCRIPTION: The proposed research consists of a series of experiments which use the process dissociation procedure, developed by the principal investigator to decompose performance into separate quantitative estimates of the contributions of consciously controlled and automatic processes, to investigate the role of context or environmental support in memory performance. These experiments are expected to show that contextual information can be used both intentionally and unintentionally (automatically), and that separating the two types of effects is important for maximizing beneficial effects of environmental support. A second set of experiments focuses on automatic influences as involved in the development of implicit learning, and a third on age-related changes in selective attention and set switching. Together these sets of experiments will be used to examine differential effects of aging.

DESCRIPTION (Applicant's Abstract): Successful language comprehension requires the computation and integration of several conceptually distinct types of information. Two exigencies are the recovery of linguistic information from long-term lexical memory and the computation of a structured representation. This program of research investigates the essential nature of these component processes as they apply to language comprehension in normal, intact populations. The primary aim of the project is to specify the computational structure of lexical and syntactic processes, a necessary precursor to the development of well-specified computational models of natural language understanding. Using procedures that tap the time-course of processing and procedures that measure processing resources, we investigate whether these processes have an intrinsic serial or parallel capacity. We examine whether lexical retrieval processes recovery of the exhaustive set of syntactic structures associated with key elements in a sentence. Results in hand indicate that lexical retrieval is parallel but short of exhaustive, suggesting that limited retrieval constrains subsequent syntactic and interpretative processes. To better understand these constraints, experiments are designed to identify factors that control the probability of retrieving syntactic information from lexical representations. Concerning parsing operations, we investigate whether more than syntactic representation is computed during on-line processing. One set of experiments addresses the issue of parsing capacity at the level of immediate structure building, while other experiments examine how parsing routines respond to ambiguous material. Preliminary results suggest that several lexical syntactic structures are applied in parallel in the initial phase of structure building. Experiments are proposed to explore this finding further and to examine whether contextual information can restrict initial structure building operations. An additional set of experiments investigates how readers respond to temporarily ambiguous material, examining whether more than one representation is computed and maintained over an ambiguous region. Finally, a third set of experiments investigates how lexical and interpretative processes successfully converge on the correct interpretation of syntactically unambiguous but indeterminate structures. We argue that lexical and syntactic processes must be supplemented by a type of enriched interpretative processing.

With National Science Foundation support, Dr. Brian McElree will conduct three years of psycholinguistic research on people's interpretation of simple and complex expressions. Language comprehension requires operations ranging from the identification of individual words to the construction of a suitable interpretation for a complete text or utterance. Recent formal analyses suggest that complex operations are needed to derive a contextually suitable interpretation of even common and seemingly simple expressions. These operations appear to modify default interpretations of individual constituents, and they often generate semantic content that is not explicitly represented in the sentence or discourse. This project seeks to identify the processes and knowledge structures used in language comprehension, and to determine whether some compositional processes draw on local lexical properties rather than world knowledge. Experiments will dissociate simple and enriched forms of composition and so identify the properties that distinguish these different forms of composition. On-line measures of sentence processing (eye-movement patterns, self-paced reading times, and time-course functions derived from the speed-accuracy tradeoff procedure) will contrast expressions hypothesized both to depend on different types of information and to engage different kinds of compositional operations. The experiments will examine how local (phrase-internal) and global constraints affect composition, and whether there are aspects of the compositional process that operate in a context-insensitive manner.
This project will advance our understanding of the critical interface between lexical and syntactic processing on one hand and discourse and text comprehension on the other. The research should also have implications for formal linguistic theory, as well as for the development of efficient natural language understanding systems. Moreover, as some aphasics show selective deficits in understanding expressions requiring enriched composition, this research may also aid in the characterization of particular language disorders and illuminate the neural structures serving language processing. The project will also provide valuable research experience for undergraduates and advanced training for postdoctoral students.

[unreadable] DESCRIPTION (provided by applicant): The goal of the proposed project is to characterize the memory representations and operations that enable successful comprehension of language in real-time. Understanding written and spoken language routinely requires readers and listeners to establish dependencies between sentential elements that span several words, phrases, or even clauses. To fully integrate new information into an evolving interpretation of the discourse, comprehenders must gain access to the memory representations associated with earlier parts of the text or utterance. Despite the centrality of memory to comprehension, research has not clearly identified (a) when information must be retrieved from memory for comprehension to be successful, (b) how information is retrieved from memory, and (c) what factors determine the success of retrieval. These questions form the core of this project, and we propose to address them with conventional eye-tracking procedures during reading and with speed-accuracy tradeoff (SAT) procedures. The use of SAT is a unique aspect of this proposal. The method has been widely used to gain information about memory and attention processing, and its application in the realm of sentence processing will enable precise measurements of how the interpretations of different sentence structures unfold over time, as well as tests of hypotheses that cannot be evaluated with conventional measures alone. Building on basic memory research and preliminary findings in comprehension, the project addresses the following hypotheses: (a) Retrieval from memory is required whenever on-going processing displaces representations from a very limited focus of attention. We will investigate the effective span of focal attention in comprehension, and whether it interacts with linguistic structure and linguistic devices for focusing information. (b) Different models for how retrieval operates have been proposed. We test these models, and specifically investigate the hypothesis that representations formed during comprehension are content-addressable and retrieved with a direct-access operation. (c) Interference is a major determinant of retrieval failures. We explore the hypothesis that retrieval interference is a significant determinant of successful comprehension, and that it may determine the limits on our ability to interpret complex sentence structures. PUBLIC HEALTH RELEVANCE: The memory mechanisms that we propose to investigate in this project comprise the basic building blocks necessary for skilled language and reading comprehension. We anticipate that the project will provide benchmark data on attentional span, the nature of retrieval, and the role of interference in comprehension in normal populations. The project will provide a detailed and comprehensive foundation for future investigations of developmental changes, individual differences, and abnormalities within the comprehension system. [unreadable] [unreadable] [unreadable]

Research on human sentence processing seeks to understand the moment-to-moment computations that enable competent speakers of a language to understand and produce sentences. Progress in this domain requires an interdisciplinary approach, one that draws upon the expertise and tools developed in several fields. Those tools include experimental and observational methods developed in psychology and neuroscience; descriptive, comparative and deductive techniques developed in theoretical linguistics and philosophy; and computational techniques for creating and analyzing language corpora to acquire information about language use. This proposal focuses on recent advancements in technologies for tracking brain activity during language comprehension. The funds support a special session on the cognitive neuroscience of sentence processing to be held in conjunction with the 2010 meeting of the CUNY Conference on Human Sentence Processing (March 18-20, 2010), as well as a 2-day pre-conference tutorial workshop (March 16-17, 2010). The special session is designed to showcase cutting edge neurolinguistic research using different technologies. The workshop is designed to provide a detailed presentation of standard and emerging neuroimaging and brain monitoring technologies, such as electroencephalography (EEG), functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), transcranial magnetic stimulation (TMS), and near infrared spectroscopy (NIRS).

The special session and the workshop will help both new and established researchers meet one of the major challenges to investigating a complex system such as language comprehension. Unquestionably, progress is best made when a variety of experimental techniques are used to investigate different aspects of the comprehension system. Expanding a researcher's skill set is challenging in the best of circumstances, but particularly so when it involves cognitive neuroscience techniques, which are developing at an extremely rapid rate. The special session and the tutorial workshop will create important and unique opportunities for language researchers to interact with highly successful scientists who use neural methods to address core questions in sentence processing. Minimally, this exposure should enable a researcher to become an "informed consumer" of relevant research using these new methodologies. For cases where these approaches could be fruitfully applied to core questions in a researcher's area of expertise, this exposure may induce the researcher to seek out further training or collaborations to capitalize on the advantages of combining one of these approaches with those currently used. Although valuable to all in attendance, the special session will provide a unique opportunity for graduate and postdoctoral students to learn about cutting-edge research using methods that were not part of their training regime, as well as to interact with leading scientists using those methods.