Recent research in psycholinguistics has largely focused on adults under thirty, often assuming that language abilities remain stable after acquisition, a view now challenged by emerging evidence (Griffin and Spieler, 2005). This research addresses that gap by investigating how healthy aging affects language comprehension in Spanish, with a particular focus on predictive processing and agreement computation.

The work is framed within two complementary theoretical perspectives: the resource based hypothesis (Salthouse, 1996; Wlotko et al., 2012), which attributes age-related decline to reduced cognitive resources, and the experience-based hypothesis (Horn and Cattell, 1967; Federmeier and Kutas, 2005; Payne and Stine-Morrow, 2016), which emphasizes the compensatory role of lifelong linguistic knowledge. To evaluate these accounts, a series of eye-tracking experiments were conducted with young and older adults, examining how working memory capacity, executive control (inhibition and monitoring and updating), and language experience (vocabulary size and reading habits) shape lexical and morphosyntactic prediction.

Results indicate that lexical prediction is largely preserved across the lifespan, although it unfolds differently: younger adults anticipate upcoming words more efficiently, whereas older adults show increased integration difficulty with unexpected items. In contrast, morphosyntactic prediction shows clearer age-related decline, with older adults exhibiting heightened sensitivity to ungrammaticality and agreement attraction errors. Cognitive mechanisms contribute differently across linguistic domains and age groups: working memory supports early lexical prediction and later error resolution, monitoring and updating are crucial for agreement processing in older adults, and inhibitory control influences both domains. Importantly, language experience exerts a strong compensatory effect, particularly in older adults, supporting the experience-based hypothesis for lexical prediction, while resource limitations appear more critical for morphosyntactic agreement.

Overall, this research broadens our understanding of how cognitive abilities and linguistic experience interact to support comprehension across the adult lifespan, highlighting both preserved and declining aspects of language processing in healthy aging