This research revealed both similarities and striking differences in early language proficiency among infants from a broad range of advantaged and disadvantaged families. English-learning infants (n = 48) were followed longitudinally from 18 to 24 months, using real-time measures of spoken language processing. The first goal was to track developmental changes in processing efficiency in relation to vocabulary learning in this diverse sample. The second goal was to examine differences in these crucial aspects of early language development in relation to family socioeconomic status (SES). The most important findings were that significant disparities in vocabulary and language processing efficiency were already evident at 18 months between infants from higher- and lower-SES families, and by 24 months there was a six-month gap between SES groups in processing skills critical to language development.

This study compares the prosodie modifications in mothers' and fathers' speech to preverbal infants in French, Italian, German, Japanese, British English, and American English. At every stage of data collection and analysis, standardized procedures were used to enhance the comparability across data sets that is essential for valid cross-language comparison of the prosodie features of parental speech. In each of the six language groups, five mothers and five fathers were recorded in semi-structured home observations while speaking to their infant aged 0; 10–1;2 and to an adult. Speech samples were instrumentally analysed to measure seven prosodic parameters: mean fundamental frequency (f0), f0-minimum, f0-maximum, f0-range, f0-variability, utterance duration, and pause duration. Results showed cross-language consistency in the patterns of prosodic modification used in parental speech to infants. Across languages, both mothers and fathers used higher mean-f0, f0-minimum, and f0-maximum, greater f0-variability, shorter utterances, and longer pauses in infant-directed speech than in adult-directed speech. Mothers, but not fathers, used a wider f0-range in speech to infants. American English parents showed the most extreme prosodic modifications, differing from the other language groups in the extent of intonational exaggeration in Speech to infants. These results reveal common patterns in caretaker's use of intonation across languages, which may function developmentally to regulate infant arousal and attention, to communicate affect, and to facilitate speech perception and language comprehension. In addition to providing evidence for possibly universal prosodic features of speech to infants, these results suggest that language-specific variations are also important, and that the findings of the numerous studies of early language input based on American English are not necessarily generalisable to other cultures.

To explore how online speech processing efficiency relates to vocabulary growth in the 2nd year, the authors longitudinally observed 59 English-learning children at 15, 18, 21, and 25 months as they looked at pictures while listening to speech naming one of the pictures. The time course of eye movements in response to speech revealed significant increases in the efficiency of comprehension over this period. Further, speed and accuracy in spoken word recognition at 25 months were correlated with measures of lexical and grammatical development from 12 to 25 months. Analyses of growth curves showed that children who were faster and more accurate in online comprehension at 25 months were those who showed faster and more accelerated growth in expressive vocabulary across the 2nd year. Keywordsinfant language comprehension; infant speech processing; lexical development; eye-tracking; online measures Children in the early stages of learning a language are often credited with "acquiring" new vocabulary, as if words come one by one into the child's possession. When we speak of acquiring something like a piano or a piece of property, the emphasis is on ownership, an odd way to characterize the complex and incremental processes involved in word learning. However, we also speak of acquiring skills, such as playing the piano, in which the emphasis is on gradual mastery rather than possession. It is increasingly evident that learning to recognize, understand, and speak a new word appropriately is a gradual process. Not only do infants respond meaningfully to more and more words over the 2nd year, they also respond with increasing speed and efficiency to each of the words they are learning. That is, rather than "acquiring" a new word in an all-or-none fashion, they get better at recognizing and interpreting the same word in more diverse and challenging contexts.Because comprehension is a mental activity not easily observable in infants' spontaneous behavior, the gradual emergence of understanding has been difficult to study with precision. However, with the refinement of procedures that track listeners' eye movements as they scan a visual array in response to speech, a technique used widely in research with adults (Tanenhaus, Magnusen, Dahan, & Chambers, 2000), it is now possible to monitor the time course of spoken language understanding in very young children. Using a looking-whilelistening procedure with infants from 15 to 24 months of age, Fernald, Pinto, Swingley, Weinberg, and McRoberts (1998) NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript understanding increase dramatically over the 2nd year. In that study, infants looked at pictures of objects while listening to speech naming one of the objects with a familiar word. Whereas 15-month-olds responded inconsistently and shifted their gaze to the correct picture only after the end of the target word, 24-month-olds were faster and more reliable in their responses, initiating a shift in gaze midway through the target word based on partial p...

The prosodic characteristics of "motherese" were examined in the speech of 24 German mothers to their newborns. Each subject was recorded in three observational conditions, while addressing (a) her 3-to 5-day-oId baby (M-B Speech); (b) the absent infant, as if present (Simulated M-B Speech); and (c) the adult interviewer (M-A Speech). For each subject, 2-minute speech samples from each condition were acoustically analyzed. It was found that in M-B Speech, mothers spoke with higher pitch, wider pitch excursions, longer pauses, shorter utterances, and more prosodic repetition than in M-A Speech. Furthermore, 77% of the utterances in the M-B Speech sample conformed to a limited set of prosodic patterns that occurred only rarely in adult-directed speech, i.e., they consisted of characteristic "expanded" intonation contours, or they were whispered. The prosody of mothers' speech is discussed in terms of its immediate influence within the context of motherinfant interaction, as well as its potential long-range contribution to perceptual, social, and linguistic development.

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