Undergraduates: Interested in obtaining first-hand experience conducting research? Contact Dr. Kemtes at kkemtes@unlv.nevada.edu   Cognition in Aging Research Program Aims A specific aim of my research is to examine how individuals with constraints on working memory resources, particularly older adults (65+ years), comprehend complex written and spoken communication. This work also focuses on the individual differences which characterize adult cognitive aging processes. Two substantive questions guide this work: (1) What are the relations between memory (particularly working memory) and language processes? and (2) How do our models of cognitive aging inform these relations? Written Language Processing & Working Memory (Supported by NIA Pre-doctoral Traineeship) Older adults find structurally (syntactically) complex language more difficult to imitate, recognize, and recall relative to college-aged individuals. These processing difficulties have been attributed to older adults’ insufficient availability of working memory resources (Kemper, 1992). Of primary concern is where the processing "bottleneck" exists: during the initial moment-to-moment (on-line) comprehension of language or later downstream when integration or recall is required (off-line) and where the impact on working memory would be greatest. My initial studies, in the laboratory of Dr. Susan Kemper (Kemtes & Kemper, 1997) were among the first to compare these two hypotheses. We found that older adults’ moment-to-moment self-paced reading of both simple and complex sentences paralleled that of the college-aged students whereas older adults’ off-line comprehension of the complex but not simple sentences was significantly poorer relative to the younger adults. Several additional series of studies (Kemper & Kemtes, 1999; Kemtes & Kemper, 1998; Kemtes & Kemper, 1999) followed-up on this bottleneck question. The reliable finding was that for many individuals, constraints on working memory resources do not appear to directly influence the initial moment-to-moment processing of language but rather exert their influence downstream. In my dissertation I addressed the question of why the type of processing assessed by self-paced reading is sensitive to working memory constraints for some but not other individuals. The primary focus of the studies was on other cognitive processing resources such as inhibitory functioning and speed of mental operations which also influence processing. The dissertation work reinforced the finding that working memory is the primary limiting factor in processing complex sentences but confirmed that these other resources are also important, especially for older adults. Written & Spoken Language Processing & Working Memory (Supported by NRSA/NIA Post-doctoral Fellowship) My work as an NRSA post-doctoral fellow in the speech processing in aging laboratory of Dr. Arthur Wingfield addressed the processing bottleneck issue. The rapid, transient, and on-line nature of complex speech comprehension would seem to be an ideal language situation in which to test the bottleneck hypothesis. In the first studies in this series I contrasted younger and older adults’ reading and listening patterns for simple and complex sentences which were presented using a self-paced reading or a self-paced listening task. I showed that both younger and older adults who experience working memory limitations (as measured by a composite index of working memory tasks) experience differentially greater processing difficulties both on-line and off-line—but only in the spoken presentation condition. These differences were not attributable to older adults’ slightly poorer hearing acuity. The first papers in this series, a methodological  comparison of the self-paced reading and listening paradigms, has been submitted for publication. Current Projects Current projects include comparing experimenter- and participant-paced written and spoken language presentation methods, evaluating the role of cognitive workload and working memory in language processing models, assessing the role of context in disambiguating ambiguous language, introducing new computer-based techniques to improve written and spoken text and question comprehension, and examining the benefits of simultaneous audio-visual language presentation. This work had contributed to a grant proposal to the Spencer Foundation (pending). I am also applying theoretical models of cognitive constraints on spoken and written language processing to practical concerns with aging such as comprehending closed-caption television and comprehending health information. Both of these projects are funded via internal grants (please see vita for details) and the resulting pilot data will contribute to an R01 proposal. Cognitive Construct Validation A parallel line of investigation is designed to explore and refine our multi-dimensional theories of working memory. While there is general agreement that working memory is a short term, limited capacity information processing mechanism in which storage capacity and processing efficiency are the allocated resources, there is little agreement as to whether this mechanism is driven by a central executive processor (e.g. Baddeley, 1986) or multiple domain-specific executive systems (e.g. Daneman & Carpenter, 1980). Studies of older adults’ working memory have generated a novel set of issues to contend with regarding the measurement of working memory—particularly the issue of how younger and older individuals differ with respect to storage and capacity. One consistent finding in aging research is that more complex working memory tasks do not reliably yield larger age effects than less complex tasks. Note that there are few well-defined criteria for ‘simple’ versus ‘complex’ working memory span tasks, other than the general stipulation that a complex task involve the ‘simultaneous’ storage and processing of information. The focus of my research on working memory is to address the issue of reliably defining and measuring the construct— particularly in different age groups. To date, few measures of working memory have been tested for reliability within samples or invariance across samples. It is generally assumed that a particular working memory task measures the same construct— regardless of the samples being tested. My initial explorations of this topic (Kemtes & Kemper, 1997; 1999; 2001) focused on a multi-method approach to measuring working memory in which I created composite indexes which were based on a common working memory factor. Expanding on this work, I tested whether within studies a simple factor analytic structure with a single latent variable of working memory was reliable across age groups. A single latent factor working memory model was validated across age groups suggesting that a common construct was measured. These findings suggest that working memory is better defined or measured in terms of multiple tasks which may, in part, represent different component processes of working memory (Kemtes & Kemper, 2001). Current work (Kemtes & Wingfield, submitted) focuses on modality-based issues in working memory. Summary Together, these studies are aimed at detailing human communication processes at the sentence and discourse levels as well as the cognitive constraints which underlie these processes. A second aim of this work is to examine the stability of language processes with age and determine which of those processes are affected by cognitive declines or difficulties. This work also focuses on applying models of language and cognitive processes to real-world concerns of older adults. Visit the Cognition in Aging Laboratory: http://cia.unlv.edu