How Well Do Children Remember Fast‐Mapped Words? A Pre‐Registered Meta‐Analysis of Retention Following the Mutual Exclusivity Response

ABSTRACT There is widespread evidence that children display a mutual exclusivity response upon encountering new words. Children displaying this behaviour will select a novel, name‐unknown object in response to a novel label, rather than a familiar, name‐known object. The mutual exclusivity response has been viewed as a means of fast‐mapping vocabulary—enabling the retention of new words with minimal and incidental exposure. Thus, it may play an important role in driving early vocabulary growth. Yet, while the mutual exclusivity response may initially guide the correct choice of a novel word's referent, it does not necessarily result in retention for even brief durations. In this pre‐registered meta‐analysis, we examined the evidence for the retention of novel noun mappings disambiguated through the mutual exclusivity response. While a large effect size was observed for the mutual exclusivity response, consistent with past research, there was a smaller effect for subsequent retention—which was substantially attenuated by Bayesian publication bias correction. Our findings are consistent with models of word learning in which referent selection is not governed by the same processes underlying referent retention.