The effects of cognitive changes across the adult lifespan on lexical and grammatical processing

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Life expectancy has risen dramatically in the last century, increasing many age-related challenges, which include changes to cognition. However, while the effects of aging on some aspects of cognition (e.g., processing speed, declarative memory) are quite well-studied, much less is known about age-related changes in the critical capacity of language and whether there is a relation between age-related changes in non-linguistic cognition and changes in language processing.The proposed project investigates the developmental trajectory of language processing in participants between the ages of 20 and 90 years. Using a cross-sectional within-participants design, I will examine the production and comprehension of morphologically simple and complex words and relate those findings to results from cognitive tasks (processing speed, memory). Morphological processing has been argued to involve both grammatical processing (regular/default forms) and lexical processing (irregular/non-default forms). For this reason, morphologically complex words make for a particularly good test case as they allow for the study of aging effects on different mechanisms of language processing.Work package (WP) 1 examines the comprehension and production of plural nouns using elicited production and cross-modal priming. Of particular interest is the (expected) contrast between default and non-default plurals, and whether aging affects the processing of these different plural types differently. WP 2 assesses how aging affects speakers’ production and comprehension of morphologically simple words using picture naming and lexical-decision tasks. This way, we can assess whether aging affects the processing of complex and of simple words in a similar manner, particularly regarding the onset of changes and the trajectory throughout life.Work Package 3 investigates how the effects of aging on language processing found in WPs 1 and 2 can be tied to age-related changes in non-linguistic cognition, with a focus on general processing speed and the two main learning-and-memory systems, declarative and procedural memory. Specifically, the results from this WP will address the question of whether aging exhibits global effects on language processing (i.e., on lexical and grammatical processes alike), or whether the effects are more selective, with some aspects of processing being more greatly affected than others.Besides the main goal – revealing how aging affects language –, this study should also help provide insights about aging (independent of language) and insights about language (independent of aging). The research may also have translational impacts as the findings may provide as baseline for the study of age-related disorders affecting language (e.g., Alzheimer’s disease).