Bilingualism and ageing independently impact on language processing: evidence from comprehension and production

To examine the combined effects of ageing and bilingualism in language processing, we tested young and older mono- and bilingual speakers in L1 comprehension and production. In Experiment 1, bilinguals were slower to detect words than monolinguals in sentences with a low-constraint context, but not when a high-constraint context was provided. Older adults tended to outperform younger adults in high-constraint sentences. In Experiment 2, older speakers were slower than younger speakers to produce small-scope prepositional phrases (e.g., 'the cone above the grape), suggesting more extensive planning. Bilingual disadvantages were observed in larger-scope complex phrases (e.g., 'the cone and the pink grape'). Individual differences in language proficiency did not modulate the effects. The results support bilingual disadvantages in syntactic processing and age-preserved syntax, alongside semantic processing unaffected by either bilingualism or age. We found no interactions between age and bilingualism, suggesting that these two factors independently impact language processing.