The primary focus of the Language and Aging Lab is to investigate the ways in which language processing differs between younger and older adults at both the behavioral and neural level. Past research has demonstrated that while language comprehension is generally well-maintained with increasing age, older adults often experience declines in language production abilities, which can be characterized by slower speech rates, slower and less accurate object naming, and increased frequency of tip-of-the-tongue states. Many of the current projects in our lab seek to more fully explore age differences in language production. To better understand these issues, we conduct extensive behavioral and neuropsychological assessments across a range of cognitive functions including language production. These cognitive measures can then be paired with 3 kinds of neuroimaging data: functional MRI data which examines how the brain works while performing a task, such as picture naming; resting-state MRI data which examines how the brain works while participants are alert, but not engaged in an explicit task; and structural MRI data which examines how brain structure varies across the lifespan. This approach helps us to better understand the factors that may contribute to age-related production deficits.
For example, in a recent functional MRI study, we examined age-related differences in sensitivity to word characteristics, such as phonological neighborhood density (PND). Large phonological neighborhoods (i.e., words with many similar sounding words) generally facilitate production. For example, words with large phonological neighborhoods are less likely to result in production errors in natural speech. Critically, manipulations of factors such as these provide a tractable method to examine potential mechanisms underlying age-related differences in language production.
Changes in White Matter Integrity and its Behavioral Correlates in Older Adults
Diffusion Tensor Imaging (DTI) is a neuroimaging technique that tracks the movement of water molecules through the brain. The direction in which water molecules travel is determined in part by the orientation of fiber tracts in the brain. Thus, through the use of DTI, researchers can better understand the structure of the brain and how different parts of the brain are connected to each other. Because brain structure has been shown to change with age, it is particularly important to understand how such changes may affect various aspects of cognition.To this end, we collected DTI data in both older and younger adults, as well as behavioral measures that incorporate tests of speed, recall, verbal fluency, and other executive functions. Our current project seeks to investigate the relationships among age, brain structure, and cognitive functioning.
Age-related Differences in Language Production and Prediction
Aging is often associated with declines in language production including increased word finding failures, slips of the tongue, and more pauses in speech. Language comprehension studies have shown that older adults are less likely to engage in predictive processing during reading (e.g., Federmeier & Kutas, 2005). There are several possible reasons why these age-related differences may occur – differences in cognitive resources such as in working memory or processing speed. Additionally, language production theories have also suggested that these age-related differences in prediction may be related to language production (e.g., Dell & Chang, 2014). Our current project investigates the relationships among language production, age, and prediction through the use of self-paced reading.