Isolated Words Selectively Enhance Memory for High Transitional Probability Sound Sequences

Research over the past two decades has demonstrated that infants are equipped with remarkable computational abilities that allow them to find words in continuous speech. Infants can encode information about the transitional probability (TP) between syllables to segment words from speech when tested immediately after familiarization with an artificial (e.g., Saffran, Aslin & Newport, 1996) or natural language (Pelucchi, Hay, & Saffran, 2009). However, infants’ ability to retain the sequential statistics beyond the immediate familiarization context remains unknown. In the present study, we examine infants’ memory for statistically-defined words 10- minutes following familiarization with a naturally produced Italian corpus. Eight-month-old English-learning infants were familiarized with Italian sentences that contained four embedded target words (see Pelucchi et al., 2009): two words had high internal TP (HTP, TP=1.0) and two had low TP (LTP, TP=.33) and were tested on their ability to discriminate HTP from LTP words using the Headturn Preference Procedure. When discrimination was tested following a 10-minute delay, infants listened equally to HTP and LTP words, suggesting that memory for statistical information likely decays over even short delays (Experiment 1). Experiments 2-4 were designed to test whether experience with isolated words selectively reinforces memory for statistically- defined words. When 8-month-olds were familiarized with the same corpus and then were given experience with the isolated words immediately after familiarization, they looked significantly longer to HTP words than LTP words after the 10-minute delay, suggesting that the experience with isolated words may reinforce memory for HTP words following a delay