My primary research program is concerned with developing ways to measure, understand, and improve reading comprehension skills. An assumption underlying my approach is that there are two major determinants of comprehension: the text and the reader. In the past, my research focused primarily on the contributions of the reader. My current research investigates contributions of the text and reading situation as well; for example, I am attempting to establish the degree of text difficulty and the degree of constraint on reading time that produce optimal levels of text comprehension. My early individual-differences research focused almost exclusively on developing a measure of the reader's working memory capacity and establishing that it correlates with reading comprehension. My latest research goes beyond demonstrating the correlation; it explores how working memory theory can be applied to improving comprehension in educational settings (e.g., during learning, test taking). I am also exploring other sources of difference in reading skill besides capacity differences. Brenda Hannon and I have developed and validated a new individual-differences measure that provides estimates of a reader's ability to activate and integrate long-term memory knowledge with text information, to make text-based inferences, and to recall text. We are using this measure to advance our understanding of age-related changes in reading, and to explore the cognitive and memory processes tapped by a variety of other reading, verbal reasoning, and intelligence tests, including widely-used, yet controversial, multiple-choice reading comprehension tests such as the Verbal Scholastic Assessment Test (VSAT). Although the study of reading skills remains my primary focus, I also apply my individual-differences perspective to understanding a variety of phenomena of interest to cognitive psychologists. How does working memory relate to constructs such as consciousness, attention, control? What accounts for differences in people's susceptibility to unconscious influences and distortions in long-term memory? My individual-differences approach to comprehension and memory has important educational and clinical applications.
As a member of the CIHR Research Group on Sensory and Cognitive Aging, I am involved in investigating the sensory and cognitive factors that contribute to age-related declines in speech and language comprehension. Older adults, whether or not they have clinically significant hearing loss, have more trouble than their younger counterparts understanding speech in everyday life. These age-related difficulties in speech understanding may be attributed to changes in higher-level cognitive processes such as language comprehension, memory, attention, and cognitive slowing, or to lower-level sensory and perceptual processes. The typical approach has been to focus either on cognitive declines or sensory declines in artificially optimized test conditions. In contrast, our approach focuses on the complex interactions between age-related changes in cognitive and perceptual factors that might affect spoken language comprehension, especially in non-ideal, realistic conditions. In large part, we have been finding that age-related changes in speech understanding are a consequence of auditory declines. For example, when the young and old are tested under identical physical conditions, as is typical in most cognitive aging studies, we find that the older adults have more difficulty comprehending and recalling spoken discourse. However, when we equate young and old for perceptual stress by adjusting the listening situation to take into account each individual's hearing status, the age-related comprehension differences are largely eliminated. Only rarely do cognitive aging researchers measure the perceptual abilities of their participants, and seldom (if ever) do they control for these differences. The implicit assumption is that age-related differences in perceptual abilities will have a negligible effect on cognitive performance. Our research shows that this assumption need not be valid.