In this experiment using the conditioned head-turn procedure, 18-month-old French-learning toddlers were trained to respond to either a target noun (“la balle”/the ball) or a target verb (“je mange”/I eat). They were then tested on target word recognition in two syntactic contexts: the target word was preceded either by a correct function word (“une balle”/a ball or “on mange”/they eat), or by an incorrect function word, signaling a word from the other category (∗“on balle”/they ball or ∗“une mange”/a eat). We showed that 18-month-old s exploit the syntactic context on-line to recognize the target word: verbs were recognized when preceded by a personal pronoun but not when preceded by a determiner and vice-versa for nouns. These results suggest that 18-month-olds already know noun\ud and verb contexts. As a result, they might be able to exploit them to categorize unknown words and constrain their possible meaning (nouns typically refer to objects whereas verbs typically refer to actions)

This study focuses on the development of lexical stress perception during the first year of life. Previous research shows that cross-linguistic differences in word stress organization translate into differences in word stress processing from a very early age: At 9 months, Spanish-learning infants, learning a language with variable word stress, can discriminate between segmentally varied nonsense words with initial stress (e.g., níla, túli) and final stress (e.g., lutá, pukí) in a headturn preference procedure. However, French infants, who learn a language with fixed word stress, can only distinguish between initial and final stress when no segmental variability is involved ( Skoruppa et al., 2009 Skoruppa, K. , Pons, F. , Christophe, A. , Bosch, L. , Dupoux, E. and Sebastián-Gallés, N. … Peperkamp, S. 2009. Language-specific stress perception by 9-month-old French and Spanish infants. Developmental Science, 12: 914–919. [Crossref], [PubMed], [Web of Science ®] [Google Scholar] ). The present study investigates the emergence of this cross-linguistic difference. We show that at six months, neither Spanish nor French infants encode stress patterns in the presence of segmental variability (Experiment 1), while both groups succeed in the absence of segmental variability (Experiment 2). Hence, only Spanish infants, who learn a variable stress language, get better at tracking stress patterns in segmentally varied words between the ages of 6 and 9 months. In contrast, all infants seem to be able to discriminate basic stress patterns in the absence of segmental variability during the first nine months of life, regardless of the status of stress in their native language.

Adult speakers of different free stress languages (e.g., English, Spanish) differ both in their sensitivity to lexical stress and in their processing of suprasegmental and vowel quality cues to stress. In a head-turn preference experiment with a familiarization phase, both 8-month-old and 12-month-old English-learning infants discriminated between initial stress and final stress among lists of Spanish-spoken disyllabic nonwords that were segmentally varied (e.g. [ˈnila, ˈtuli] vs [luˈta, puˈki]). This is evidence that English-learning infants are sensitive to lexical stress patterns, instantiated primarily by suprasegmental cues, during the second half of the first year of life.