Data From: A Protracted Developmental Trajectory for English-Learning Children’s Detection of Consonant Mispronunciations in Newly Learned Words

Children are adept at learning their language’s speech-sound categories, but just how these categories function in their developing lexicon has not been mapped out in detail. Here, we addressed whether, in a language-guided looking procedure, two-year-olds would respond to a mispronunciation of the voicing of the initial consonant of a newly learned word. First, to provide a baseline of mature native-speaker performance, adults were taught a new word under training conditions of low prosodic variability. In a second experiment, 24- and 30-month-olds were taught a new word under training conditions of high or low prosodic variability. Children and adults showed evidence of learning the taught word. Adults’ target looking was reduced when the novel word was realized at test with a change in the voicing of the initial consonant, but children did not show any such decrement in target fixation. For both children and adults, most learners did not treat the phonologically distinct variant as a different word. Phonetic variability during teaching did not have consistent effects. Thus, under conditions of intensive short-term training, 24- and 30-month-olds did not differentiate a newly learned word from a variant differing only in consonant voicing. High task complexity during training could explain why mispronunciation detection was weaker here than in some prior studies. We also tested 19-month-olds in the low-variability condition, because we originally predicted that children would learn words and detect one-feature mispronunciations as early as 19 months. However, 19-month-olds showed inconsistent word learning, suggesting that the narrated story we used for word teaching might have been too complex. Thus, in the article we focus on the work with 24- and 30-month-olds, presenting the 19-month-olds’ results in the Supplemental Materials. Their data are included in the data file in the interests of transparency. The Supplemental Materials accompanying the paper also report analyses of (lack of) responses to pitch mispronunciations by adults and 19-month-olds. Adults were tested with both pitch and consonant MPs. Nineteen-month-olds were tested with one or the other, due to more limited attention spans