Recordings were obtained of the comfort-state vocalizations of infants at 3, 6, and 9 months of age during a session of play and vocal interaction with the infant's mother and the experimenter. Acoustic analysis, primarily spectrography, was used to determine utterance durations, formant frequencies of vocalic utterances, patterns of f0 frequency change during vocalizations, variations in source excitation of the vocal tract, and general properties of the utterances. Most utterances had durations of less than 400 ms although occasional sounds lasted 2 s or more. An increase in the ranges of both the F1 and F2 frequencies was observed across both periods of age increase, but the center of the F1-F2 plot for the group vowels appeared to change very little. Phonatory characteristics were at least generally compatible with published descriptions of infant cry. The f0 frequency averaged 445 Hz for 3-month-olds, 450 Hz for 6-month-olds, and 415 Hz for 9-month-olds. As has been previously reported for infant cry, the vocalizations frequently were associated with tremor (vibrato), harmonic doubling, abrupt f0 shift, vocal fry (or roll), and noise segments. Thus, from a strictly acoustic perspective, early cry and the later vocalizations of cooing and babbling appear to be vocal performances in continuity. Implications of the acoustic analyses are discussed for phonetic development and speech acquisition.

nature publishing group short communications methods and techniquesThe prevalence of overweight and obesity among US children aged 5 years and under has more than tripled since the 1970's. Data from the 2007-2008 National Health and Nutrition Examination Survey (NHANES) indicate that 21% of children between the ages of 2 and 5 are overweight or obese (1). Low levels of physical activity (PA) are important contributing factor in the development and maintenance of obesity (2,3). However, methodological challenges related to the assessment of PA in young children have significantly hindered research efforts to quantify, understand, and promote PA in this population (4,5).Given the limitations of child and parent self-report instruments and the high cost and participant burden associated with other objective assessment methods, accelerometry has become a popular method for measuring PA in children under five (5,6). Indeed, over the last decade, a considerable amount of research has been conducted to establish the validity of accelerometry in preschool-aged children and to identify intensity-related count thresholds for estimating time spent in sedentary (SED), light, and moderate-to-vigorous PA (5,6). To date, however, no cut-points have been developed for toddlers (<3 years) and the question of whether intensity-related thresholds established for preschool-aged children are valid for toddlers has not been adequately explored in the research literature.Therefore, the aims of this study were to: (i) derive ActiGraph cut-points for SED, light, and moderate-to-vigorous PA (MVPA) in toddlers; and (ii) evaluate the predictive validity of the new toddler cut-points and cut-points developed for preschool-aged children in an independent sample of toddlers. Methods Participants and settingStudy participants were recruited in two waves from two licensed child care centers. The first wave of participants served as the validation and calibration sample and comprised 22 toddlers (14 girls, 8 boys) between the ages of 16 and 35 months (mean age = 2.1 years ± 0.4 years). The second wave of participants served as the cross-validation sample and comprised 18 toddlers (10 girls, 8 boys) between the ages of 16 and 35 months (mean age = 2.3 ± 0.4 years). None the participants had any limitations that restricted their participation in active play or structured PA. The protocol for this study was reviewed and approved by the Kansas The purpose of this study was to derive ActiGraph cut-points for sedentary (SED), light-intensity physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) in toddlers and evaluate their validity in an independent sample. The predictive validity of established preschool cut-points were also evaluated and compared. Twenty-two toddlers (mean age = 2.1 years ± 0.4 years) wore an ActiGraph accelerometer during a videotaped 20-min play period. Videos were subsequently coded for physical activity (PA) intensity using the modified Children's Activity Rating Scale (CARS). Receiver operating characteri...

Two models of the compelling nature of the infant cry and its effectiveness in eliciting caregiving behavior are examined. The first model is that of the cry as a releaser of parental behavior. It is suggested that a good fit between the available data and this model depends upon broadening the classical definition of the releaser concept to include motivational factors in a manner advocated by some of the modern ethologists. A model of the cry as an activator of motives of an egoistic or altruistic nature is also examined. This model, based on Hoffman's theory of altruistic motivation, contributes to an understanding of both the compelling releaserlike effects of the cry as well as the wide variations observed within and between cultures in the nature and extent of caregiver responsiveness. It is further argued that altruistic behavior toward crying infants in particular must be viewed within the specific context of ontogenetic processes that enhance the attractiveness of the young for adult caregivers.

The purpose of this study was to examine the relation of maternal interaction styles to the development of a sample of 56 toddlers (19 low risk, 37 high risk) seen at 12 and 24 months of age. At 12 months, videotapes of mother–child interaction were coded for directiveness, sensitivity, and elaborativeness. At 12 and 24 months, cognitive and language measures were collected. A directive maternal style was negatively correlated with sensitivity and elaborativeness, whereas sensitive and elaborative ratings were positively correlated, suggesting a facilitative style. Regression models significantly predicted receptive language and cognitive development at 24 months but not expressive language. Maternal directiveness at 12 months was negatively related to later receptive language skills, whereas elaborativeness at 12 months was positively predictive of later cognitive development. Child status variables and maternal interactional styles contributed about equally to the prediction of later cognitive and language outcomes.

Group disparities in health have been documented for several decades. Despite recent efforts to eliminate them, group differences persist and challenge the ability of scientists to address them using traditional research paradigms. Because the determinants of disparities occur at multiple levels, from the molecular to the societal, and interact with one another in ways not yet fully understood, they represent a challenge to researchers attempting to capture their complexity. After reviewing existing models of disciplinary collaboration, we outline the challenges of a transdisciplinary approach and its ability to afford the holistic view of disparities needed to develop effective interventions.

The purpose of this study was to determine (1) whether mothers simplify their speech during the second half of the first year of development when infants begin to comprehend words and use gestures to communicate intentionally, and (2) whether individual differences in mothers' speech adjustments influence their infants' later language acquisition. The subjects for the study were 14 mother-infant pairs from a medically low risk sample who were followed longitudinally. Mothers' mean length of utterance (MLU) was calculated from transcripts of face-to-face interaction when the infants were 0;3, 0;6, and 0;9 in age. Mothers who provided responsive and stimulating environments, as indicated by HOME scores, also reduced their MLU over the age range studied. Moreover, mothers' MLU adjustments during the first year were more predictive than the HOME scale in forecasting receptive language development at 1; 6. In contrast, expressive language abilities at 1; 6 were unrelated to the environmental variables measured but were predicted by child characteristics such as the infant's sex. These results suggest that a mother's ability to ‘fine-tune’ her early linguistic input may be predictive of her child's later receptive language functioning. Precursors of fine-tuning, such as maternal beliefs in reciprocity and infant object orientation, are discussed.

The authors selected 58 mother-child dyads from divorced and intact families to participate in a study on the impact of divorce on preschoolers' attachment security. The authors explored pathways that lead to security of attachment. They found that mothers from divorced families were younger, had lower income levels, and had lower levels of education compared with their intact counterparts. Divorced mothers also reported significantly higher levels of stress, depression, need for social support, and conflict with their spouses. Mothers from intact families were more likely to use positive (authoritative) parenting styles compared with divorced mothers. Children in the divorced group had lower security scores on the Attachment Q-Set instrument (E. Waters, 1995). Regression analyses indicated that parenting style made a direct (independent) contribution to attachment security. In addition, temperament was related to attachment security, but temperament did not diminish the association of parenting style with attachment security. Furthermore, regression analyses indicated that the relationship of divorce to attachment security was mediated by parenting style.

This study explored the interrelations among attachment, home stimulation, and language development in 58 toddlers (36 medically high risk and 22 low risk) at 24 months of age. The results indicated that there were additive effects of attachment and home stimulation on language competence, especially on receptive abilities. Mothers who had established secure relationships and provided stimulating home environments had children with the highest language scores.