The real-time dynamics of language processing across the lifespan

University Of Iowa, Iowa City IA

Investigators

Abstract

Project Summary Aging is accompanied by both auditory and cognitive declines that impact psychosocial well-being and quality of life. Communication difficulties increase fatigue and can lead individuals to withdraw from social situations. This in turn can exacerbate declines by reducing social engagement. Prior work has focused on domain general aspects of cognition such as working memory and cognitive control. However, language processing— an understudied capacity in aging—may serve as a critical mediator between audition, cognitive factors and outcomes. This project focuses on spoken word recognition, a complex cognitive process that requires listeners to encode auditory information, manage competitors, and activate meaning. This is a crucial bridge between auditory function, multiple levels of language processing, and domain-general cognition. We assess this using eye-tracking in the Visual World Paradigm, which can characterize the precise competition process that undergirds spoken word recognition by tracking participants’ eye movements to pictured lexical candidates while speech unfolds in real time. Our prior work has used this technique with individuals from 11 to 79 and found increasing efficiency of word recognition through about age 30, with declines beginning around 45. However, it is unknow how these declines are related to other auditory and cognitive factors, and if there are changes that are uniquely due to word recognition. Thus, first aim investigates the factors that give rise to age- related change in word recognition. We assess a large, continuous age sample across the adult lifespan (ages 30-90, N=240). We investigate two primary predictors: 1) age-related changes in the auditory periphery—both the detectability of quiet sounds and the ability to encode fine grained temporal and spectral differences; and 2) multiple domains of cognitive function (language, working memory, and cognitive control). We relate this to online spoken word recognition assessed with the Visual World Paradigm to determine whether word recognition is a unique locus of aging and whether these other capacities contribute. With the same large sample, the second aim examines the relationship between differences in online spoken word recognition and psychosocial outcomes. We assess outcomes using both standardized measures of well-being, and by using a novel social network approach that models the complexity, diversity, and robustness of an individual’s social network. We test a model where language processing mediates the relationship between auditory and cognitive factors and psychosocial well-being. Addressing these aims is important for multiple aspects of the science of aging. First, many older adults report difficulty with speech understanding, even with normal hearing; these aims could help understand this problem. Second, spoken word recognition represents an adaptable skill that is amenable to training, if specific profiles are linked to better outcomes. Third, most cognitive assessments require language skills, but the decline in language is not known. Finally, the early decline of language skills may serve as a leading indicator of more serious decline in the future.