Learning new meanings for known words: biphasic effects of prior knowledge

Long after knowing the meaning of roller-“skate”, one may learn that “skate” is also a kind of fish. Such learning of new meanings for familiar words involves two potentially contrasting processes: form-based familiarity may facilitate the learning, and meaning-based interference may be inhibitory. We had native speakers learn new meanings for familiar and less familiar words, as well as for unfamiliar (novel) words. Tracking learning at several points revealed a biphasic pattern: higher learning rates and greater learning efficiency for familiar words relative to novel words early in learning and a reversal of this pattern later. After meaning learning, lexical access to familiar, but not to less familiar, words became faster than exposure controls. Overall, the results suggest that form-based familiarity facilitates learning earlier, while meaning-based interference becomes more influential later. The co-activation of new and old meanings during learning may play a role in lexicalisation of new meanings.