Infants learn nouns during object-naming events--moments when caregivers name the object of infants' play (e.g., ball as infant holds a ball). Do caregivers also label the actions of infants' play (e.g., roll as infant rolls a ball)? We investigated connections between mothers' verb inputs and infants' actions. We video-recorded 32 infant-mother…

Fine motor skills enable children to make precise and coordinated movements with their hands and support their ability to engage in everyday activities and learning experiences. In a longitudinal study of 1,058 4-year-old children in rural Pakistan (n = 488 girls), we examined how prior and concurrent levels of home stimulation relate to change in…

Fragmented sleep is common in infancy. Although night awakening is known to decrease with age, in some infants night awakening is more persistent and continues into older ages. However, the influence of fragmented sleep on development is poorly known. In the present study, the longitudinal relationship between fragmented sleep and psychomotor…

Infants' motor skill development triggers changes in parent-infant interactions, exploration, and play behaviors, particularly during periods of locomotor transitions. We investigated how these transitions reorganized infants' and mothers' explorations of spatial layouts. Thirteen infants and their mothers were followed biweekly from the age of 6…

Studies conducted in Western countries document the special role of mother--infant face-to-face exchanges for early emotional development including social smiling. A few cross-cultural studies have shown that the Western pattern of face-to-face communication is absent in traditional rural cultures, without identifying other processes that promote…

Using the concepts of sensory and affective experience, this work relates the concepts of socialization and cognitive development to the embodiment of gender in the human infant. Evidence obtained from biweekly observations from 30 children and their mothers observed from age 3 months to age 12 months revealed measurable sex-related differences in…

Depressive syndrome and disorders increase substantially during adolescence. Little is known, however, about how "individual" symptoms of depression change over the course of this developmental period. The present study examined within-person changes in symptom severity of each individual symptom of depression, utilizing longitudinal…

The authors examined the effects of locomotor experience on infants' perceptual judgments in a potentially risky situation--descending steep and shallow slopes--while manipulating social incentives to determine where perceptual judgments are most malleable. Twelve-month-old experienced crawlers and novice walkers were tested on an adjustable…