Representations involved in short-term versus long-term word learning by preschool children with and without phonological disorders

This study explores whether sublexical (i.e., individual sound) and/or lexical (i.e., whole-word) representations contribute to word learning and whether these contributions change across short-term versus long-term learning. Sublexical representations were indexed by phonotactic probability, the likelihood of occurrence of a sound sequence, whereas lexical representations were indexed by neighborhood density, the number of similar sounding words. Thirty-four preschool children participated in a short-term word learning task that exposed them to nonwords varying in phonotactic probability and neighborhood density and tested learning of these nonwords. Long-term learning was assessed through comprehension and production of real words varying in phonotactic probability and neighborhood density. Results showed that phonotactic probability and neighborhood density equally influenced short-term word learning. In contrast, long-term word learning was affected primarily by neighborhood density. Thus, both sublexical and lexical representations appeared to play a role in short-term learning, but only lexical representations played a primary role in long-term retention. This pattern held for both children with normal phonological development and children with phonological delays. However, the direction of the effect of neighborhood density for short-term word learning varied by group status, suggesting differences in the use of lexical representations during short-term learning. [Work supported by NIH.]