Lexical and child-related factors in word variability and accuracy in infants.

The present study investigated the effects of lexical age of acquisition (AoA), phonological complexity, age and expressive vocabulary on spoken word variability and accuracy in typically developing infants, aged 1;9-3;1. It was hypothesized that later-acquired words and those with more complex speech sounds would be produced more variably and less accurately than earlier-acquired words and those with less complex speech sounds. It was also hypothesized that word variability would decrease and word accuracy would increase with increasing age and vocabulary knowledge. Participants' productions of 20 target words, experimentally controlled for AoA and phonological complexity, were audio-recorded during a play session. Results revealed a nonsignificant effect of AoA on variability and accuracy, a significant effect of phonological complexity on variability and accuracy, a significant effect of age on variability and accuracy and a significant effect of vocabulary on variability. Theoretical and clinical implications are discussed.