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 monolingual and bilingual speakers in L1 comprehension and production. In Experiment 1, bilinguals detected words slower than monolinguals in sentences with low-constraint context, but not when high-constraint was provided. Older adults outperformed younger adults in high-constraint sentences. In Experiment 2, older speakers were slower than younger 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’). The results overall 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 on language processing.