Prosody outweighs statistics in 6-month-old German-learning infants' speech segmentation

It is well established that infants use various cues to find words within fluent speech from about 7 to 8 months of age. Research suggests that two main mechanisms support infants' speech segmentation: prosodic cues like the word stress patterns, and distributional cues like transitional probabilities (TPs). We tested 6-month-old German-learning infants' use of prosodic and statistical cues for speech segmentation in three experiments. In Experiment 1, infants were familiarized with an artificial language string where TPs signaled either word boundaries or iambic words—a stress pattern that is disfavored in German. Experiment 2 was a control and only the test phase was presented. In Experiment 3, prosodic cues were absent in the string and only TPs signaled word boundaries. All experiments included the same conditions at test: disyllabic words with high TPs in the string, words with low TPs and words with non-co-occurring syllables. Results showed that infants relied more strongly on prosodic cues than on TPs for word segmentation. Notably, no segmentation evidence emerged when prosodic cues were absent in the string. This finding underlines early impacts of language-specific structural properties on segmentation mechanisms.