Von Holzen, K. , Wolff, D. & Mani, N.
Georg-August-Universität Göttingen
To build up a vocabulary, the infant must extract, or segment, individual words from the language being spoken around them. Research has shown that at 7.5-months-of-age, infants are able to segment words from sentences (Jusczyk & Aslin, 1995) presented in infant-directed speech (IDS). However, only 15% of the speech in the infants' environment is infant-directed (van der Weijer, 2002). At what age, then, do infants begin to segment words from "normal" or adult-directed speech (ADS)? The current study tested German 12-month-olds on their ability to segment both IDS and ADS. Infants were presented with 40 familiarization-test blocks, half in IDS and the other half in ADS. In the familiarization phase, infants heard eight sentences, each containing the same (familiarized) word. In the test phase, infants heard the familiarized word and an unfamiliar control word. ERPs time-locked to the onset of the words in the test phase were examined for differences between familiarized and control words in IDS and ADS blocks. If infants extract the phonological form of the familiarized word from the sentences, recognition of this word-form should be indicated by more negative ERPs for familiarized compared to control words. As predicted ERPs were more negative following familiarized compared to control words, 200-350ms after word onset in the test phase: infants successfully segmented the familiarized words from the sentences and recognized these words later in the test phase. The effect for IDS was greater than ADS; however, this difference was not significant. In summary, the current study demonstrates that German infants, as young as 12-months-of-age, are able to segment words from both ADS and IDS. This may provide further support to infants' ability to begin producing words by 12-months of age and their rapid vocabulary development later in the second year of life (Bloom, 1973).