Lexical and phonological effects in early word production.

Purpose: This study examines the influence of word frequency, phonological neighborhood density (PND), age of acquisition (AoA), and phonotactic probability on production variability and accuracy of known words by toddlers with no history of speech, hearing, or language disorders.

Method: Fifteen toddlers between 2;0 (years;months) and 2;5 produced monosyllabic target words varying in word frequency, PND, AoA, and phonotactic probability. Phonetic transcription was used to determine (a) whole-word variability and (b) proportion of whole-word proximity (PWP; Ingram, 2002) of each target word produced.

Results: Results show a significant effect of PND on PWP and variability (words from dense neighborhoods had higher PWP and lower variability than those from sparse neighborhoods), a significant effect of word frequency on variability (high-frequency words were less variable) but not proximity, and a significant effect of AoA on proximity (earlier acquired words had lower PWP) but not variability.

Conclusions: Results provide new information regarding the role that lexical and phonological factors play in the speech of young children; specifically, several factors are identified that influence variability of production. Additionally, by examining lexical and phonological factors simultaneously, the current study isolates differential effects of the individual factors. Implications for our understanding of emerging phonological representations are discussed.