Lexical organization and phonological change in treatment.

Word frequency and neighborhood density are properties of lexical organization that differentially influence spoken-word recognition. This study examined whether these same properties also affect spoken-word production, particularly as related to children with functional phonological delays. The hypothesis was that differential generalization would be associated with a word's frequency and its neighborhood density when manipulated as input in phonological treatment. Using a multiple baseline across subjects design, 8 children (aged 3;10 to 5;4) were randomly enrolled in 1 of 4 experimental conditions targeting errored sounds in high-frequency, low-frequency, high-density, or low-density words. Dependent measures were generalization of treated sounds and untreated sounds within and across manner classes as measured during and following treatment. Results supported a hierarchy of phonological generalization by experimental condition. The clinical implications lie in planning for generalization through the input presented in treatment. Theoretically, the results demonstrate that lexical organization of words in the mental lexicon interacts with phonological structure in learning.