Idioms in the aging brain: The effects of age-related cognitive decline on the processing and comprehension of idioms

The process of aging involves a decline in the brain’s executive functions. Executive functions are responsible for complex cognitive processes, such as the ability to control and plan thoughts and behavior. Compared to younger adults, elderly adults’ performance on tasks that require executive functioning is impaired (e.g., Fisk & Sharp, 2004). However, the effects of age-related decline in executive functions on language are less clear. Therefore, this project examines the effect of age-related impairments in executive functioning on the processing and comprehension of language. This question is investigated in four studies using EEG and eye-tracking. The linguistic paradigm that is used to compare younger and elderly adults’ language processing abilities consists of idioms. Idioms, such as the Dutch tegen de lamp lopen (literally: ‘to walk against the lamp’, but figuratively: ‘to get caught’) are complex expressions whose figurative meaning cannot be derived from the literal meaning of the individual words. Instead, an idiom’s meaning is disambiguated by its context. Research suggests that the disambiguation of an idiom’s meaning draws on executive functions (Zempleni et al., 2007; Lauro et al., 2008). As executive functions decline with age, elderly adults’ idiom processing may be impaired. By using idioms as a linguistic paradigm, our project provides insight in how elderly adults process ambiguous language. In addition to examining elderly monolinguals, our project will investigate elderly bilinguals to see whether the cognitive advantages of lifelong bilingualism also interact with the ability to disambiguate idiomatic language. Finally, in collaboration with the Alzheimer Research Center Groningen, idiom processing and comprehension will be studied in patients with Alzheimer’s disease, whose executive functions decline rapidly. Overall, our project can lead to an increased understanding of the relation between general executive functions and language in old age. Moreover, the high temporal precision of the research methods enables the potential use of our results as biomarkers of linguistic processing difficulties due to aging. Keywords: aging, executive functions, idioms, EEG, eye-tracking References Fisk, J. E., & Sharp, C. A. (2004). Age-related impairment in executive functioning: Updating, inhibition, shifting, and access. Journal of Clinical and Experimental Neuropsychology, 26(7), 874-890. Lauro, L. J. R., Tettamanti, M., Cappa, S. F., & Papagno, C. (2008). Idiom comprehension: a prefrontal task?. Cerebral Cortex, 18(1), 162-170. Zempleni, M. Z., Haverkort, M., Renken, R., & Stowe, L. A. (2007). Evidence for bilateral involvement in idiom comprehension: An fMRI study. Neuroimage, 34(3), 1280-1291.