Learning the meaning of a word requires forming a semantic representation that characterizes the referential exemplarsencountered with that word. However, each learning instance is ambiguous in that the word may plausibly refer to mul-tiple entities. To the extent that learners consider multiple referents under conditions of referential uncertainty, how dothese alternatives enter into learning word meaning? We employed a cross-situational word-learning paradigm with novelcreatures to investigate whether co-occurring exemplars that were considered but not selected as the words referent wouldinfluence the category prototype. We contrasted a condition where all exemplars were labeled with a word and a condi-tion where only some of the exemplars of a category were labeled with the word later in the learning phase. Preliminaryresults are consistent with the prediction that referents that are considered but not selected contribute less to the semanticrepresentation of the word than do the selected referents.

Memory requires both individuation of specific episodes aswell as extraction of gist across related experiences. Thisstudy developed a spatial memory paradigm to track changesin item memory (memory for specific locations) and gistmemory (estimate of the center of the locations) across aperiod of a month, and to measure the relation between thesetwo forms of memory. We found that item memories decayedcompared to gist memory after a month, yet there was apositive relationship between the two forms of memory thatpersisted. Moreover, item memories were biased towards gistmemory only after a month. These findings together indicatethat gist memory, initially extracted from item memories,gradually develops into a stable representation that can guideitem memory retrieval over longer durations.