Lany, J.
University of Notre Dame
Children who encode and interpret speech rapidly, an ability referred to as speech-processing efficiency (SPE), learn language more successfully (Fernald & Marchman, 2012). Critically, it is unknown precisely how SPE supports language development, as efficient encoding is not equivalent to learning key aspects of language, such as word-referent mappings and grammatical patterns. However, growing evidence suggests that tracking statistical regularities supports such learning (Graf Estes et al., 2011; Lany, 2012). Thus, the current experiment tested the hypothesis that infants' ability to encode speech is related to their ability to learn statistical patterns. Infants between 16 and 20 months (N=44), a time of dramatic gains in SPE (Fernald et al., 1998), were exposed to an artificial language containing robust statistical cues marking grammatical structure. Specifically, infants first heard phrases in which disyllabic X-words followed a-words, while monosyllabic Y-words followed b-words. Infants were then trained on pairings in which X-words referred to pictures from one semantic category (e.g., animals) and Y-words referred to pictures from the other category (e.g., vehicles). Previous studies with this language indicate that infants' ability to form categories and learn word-referent mappings is related to the strength of the statistical cues available, suggesting that the task taps statistical-learning ability (Lany & Saffran, 2010). Speech-processing efficiency was assessed by testing how quickly infants found the referents of labels generally known at this age (e.g., doggie, baby). Lexical and grammatical development were assessed with the MacArthur-Bates Communicative Development Inventory (MCDI). Infants' SPE reliably predicted performance on the statistical learning task even when controlling for age and MCDI scores. Moreover, only infants with better SPE learned statistical regularities within the language successfully. Thus, these findings provide a new window into factors that promote language development: Infants who are better able to encode speech have an advantage in learning its statistical structure.