Fast mapping but poor retention in 24-month-old infants.

Four experiments explored the processes that bridge between referent selection and word learning. Twenty-four-month-old infants were presented with several novel names during a referent selection task that included both familiar and novel objects and tested for retention after a 5-min delay. The 5-min delay ensured that word learning was based on retrieval from long-term memory. Moreover, the relative familiarity of objects used during the retention test was explicitly controlled. Across experiments, infants were excellent at referent selection, but very poor at retention. Although the highly controlled retention test was clearly challenging, infants were able to demonstrate retention of the first 4 novel names presented in the session when referent selection was augmented with ostensive naming. These results suggest that fast mapping is robust for reference selection but might be more transient than previously reported for lexical retention. The relations between reference selection and retention are discussed in terms of competitive processes on 2 timescales: competition among objects on individual referent selection trials and competition among multiple novel name–object mappings made across an experimental session.