Finding the force: a novel word learning experiment with modals

Abstract

This study investigates the semantic and pragmatic challenges of acquiring the force of English modals, which express possibility (e.g., might) and necessity (e.g., must). Children seem to struggle with modal force through at least age 4, over-accepting both possibility modals where adults would prefer necessity modals, and necessity modals in possibility situations. These difficulties are typically blamed on pragmatic or conceptual immaturity. In this study, we sidestep these immaturity issues by investigating the challenges of modal learning through a novel word learning experiment with adults, for different 'flavors' of modals: epistemic (knowledge-based) versus teleological (goal-based), and comparing novel modals with actual English modals. We find that when learning possibility modals, adult learners behave as expected: they accept novel modals in necessity situations, both in epistemic and teleological contexts, but less often after they've learned a pragmatically more appropriate necessity modal. However, when learning necessity modals, participants manage to learn the right force (i.e., reject them in possibility situations) for epistemic scenarios only; with teleological scenarios, they accept them in possibility situations. We propose that an overlap in modal flavor explains their behavior, specifically, the competition with an ability interpretation in teleological but not epistemic scenarios, which could also contribute to children's difficulty with necessity modals reported in the acquisition literature.