Anne Fernald

Four-Month-Old Infants Prefer to Listen to Motherese"

The speech register used by adults with infants and young children, known as motherese, is linguistically simplified and characterized by high pitch and exaggerated intonation. This study investigated infant selective listening to motherese speech. The hypothesis tested was that infants would choose to listen more often to motherese when given the choice between a variety of natural infant-directed and adult-directed speech samples spoken by four women unfamiliar to the subjects. Forty-eight 4-month-old infants were tested in an operant auditory preference procedure. Infants showed a significant listening preference for the motherese speech register.

Acoustic Determinants of Infant Preference for Motherese Speech

Three experiments investigated possible acoustic determinants of the infant listening preference for motherese speech found by Fernald (1985). To test the hypothesis that the intonation of motherese speech was sufficient to elicit this preference, it was necessary to eliminate lexical content and to isolate the three maior acoustic correlates of intonation: (1) fundamental frequency (Fo), or pitch: (2) amplitude, correlated with loudness; and (3) duration, related to speech rhythm. Three sets of auditory reinforcers were computer-synthesized, derived from the FO (Experiment 1). amplitude (Experiment 2). and durotion (Experiment 3) characteristics of the infant- and adult-directed natural speech samples used by Fernald (1985). Thus, each of these experiments focused on particular prosodic variables in the absence of segmental variation. Twenty 4-month-old infants were tested in on operant ouditory preference procedure in each experiment. Infonts showed a significant preference for the FO-patterns of motherese speech, but not for the amplitude or duration patterns of motherese.

SES differences in language processing skill and vocabulary are evident at 18 months.

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 6-month gap between SES groups in processing skills critical to language development.

Talking to Children Matters Early Language Experience Strengthens Processing and Builds Vocabulary

Infants differ substantially in their rates of language growth, and slow growth predicts later academic difficulties. In this study, we explored how the amount of speech directed to infants in Spanish-speaking families low in socioeconomic status influenced the development of children’s skill in real-time language processing and vocabulary learning. All-day recordings of parent-infant interactions at home revealed striking variability among families in how much speech caregivers addressed to their child. Infants who experienced more child-directed speech became more efficient in processing familiar words in real time and had larger expressive vocabularies by the age of 24 months, although speech simply overheard by the child was unrelated to vocabulary outcomes. Mediation analyses showed that the effect of child-directed speech on expressive vocabulary was explained by infants’ language-processing efficiency, which suggests that richer language experience strengthens processing skills that facilitate language growth.

Picking up speed in understanding : Speech processing efficiency and vocabulary growth across the 2nd year

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.

Speed of word recognition and vocabulary knowledge in infancy predict cognitive and language outcomes in later childhood.

The nature of predictive relations between early language and later cognitive function is a fundamental question in research on human cognition. In a longitudinal study assessing speed of language processing in infancy, Fernald, Perfors and Marchman (2006) found that reaction time at 25 months was strongly related to lexical and grammatical development over the second year. In this follow-up study, children originally tested as infants were assessed at 8 years on standardized tests of language, cognition, and working memory. Speed of spoken word recognition and vocabulary size at 25 months each accounted for unique variance in linguistic and cognitive skills at 8 years, effects that were attributable to strong relations between both infancy measures and working memory. These findings suggest that processing speed and early language skills are fundamental to intellectual functioning, and that language development is guided by learning and representational principles shared across cognitive and linguistic domains.

Rapid Gains in Speed of Verbal Processing by Infants in the 2nd Year

Infants improve substantially in language ability during their 2nd year. Research on the early development of speech production shows that vocabulary begins to expand rapidly around the age of 18 months. During this period, infants also make impressive gains in understanding spoken language. We examined the time course of word recognition in infants ages 15 to 24 months, tracking their eye movements as they looked at pictures in response to familiar spoken words. The speed and efficiency of verbal processing increased dramatically over the 2nd year. Although 15-month-old infants did not orient to the correct picture until after the target word was spoken, 24-month-olds were significantly faster, shifting their gaze to the correct picture before the end of the spoken word. By 2 years of age, children are progressing toward the highly efficient performance of adults, making decisions about words based on incomplete acoustic information.

Young Children Learning Spanish Make Rapid Use of Grammatical Gender in Spoken Word Recognition

All nouns in Spanish have grammatical gender, with obligatory gender marking on preceding articles (e.g., la and el, the feminine and masculine forms of “the,” respectively). Adult native speakers of languages with grammatical gender exploit this cue in on-line sentence interpretation. In a study investigating the early development of this ability, Spanish-learning children (34–42 months) were tested in an eye-tracking procedure. Presented with pairs of pictures with names of either the same grammatical gender (la pelota, “ball [feminine]”; la galleta, “cookie [feminine]”) or different grammatical gender (la pelota; el zapato, “shoe [masculine]”), they heard sentences referring to one picture (Encuentra la pelota, “Find the ball”). The children were faster to orient to the referent on different-gender trials, when the article was potentially informative, than on same-gender trials, when it was not, and this ability was correlated with productive measures of lexical and grammatical competence. Spanish-learning children who can speak only 500 words already use gender-marked articles in establishing reference, a processing advantage characteristic of native Spanish-speaking adults.

Grammatical Gender in L2: A Production or a Real-Time Processing Problem?.

Mastery of grammatical gender is difficult to achieve in a second language (L2). This study investigates whether persistent difficulty with grammatical gender often observed in the speech of otherwise highly proficient L2 learners is best characterized as a production-specific performance problem, or as difficulty with the retrieval of gender information in real-time language use. In an experimental design that crossed production/comprehension and online/offline tasks, highly proficient L2 learners of Spanish performed at ceiling in offline comprehension, showed errors in elicited production, and exhibited weaker use of gender cues in online processing of familiar (though not novel) nouns than native speakers. These findings suggest that persistent difficulty with grammatical gender may not be limited to the realm of language production, but could affect both expressive and receptive use of language in real time. We propose that the observed differences in performance between native and non-native speakers lie at the level of lexical representation of grammatical gender and arise from fundamental differences in how infants and adults approach word learning.

How vocabulary size in two languages relates to efficiency in spoken word recognition by young Spanish-English bilinguals*

Research using online comprehension measures with monolingual children shows that speed and accuracy of spoken word recognition are correlated with lexical development. Here we examined speech processing efficiency in relation to vocabulary development in bilingual children learning both Spanish and English (n=26 ; 2 ; 6). Between-language associations were weak: vocabulary size in Spanish was uncorrelated with vocabulary in English, and childrens facility in online comprehension in Spanish was unrelated to their facility in English. Instead, efficiency of online processing in one language was significantly related to vocabulary size in that language, after controlling for processing speed and vocabulary size in the other language. These links between efficiency of lexical access and vocabulary knowledge in bilinguals parallel those previously reported for Spanish and English monolinguals, suggesting that childrens ability to abstract information from the input in building a working lexicon relates fundamentally to mechanisms underlying the construction of language.