Explored genetic and environmental underpinnings of temperamental differences in 3- to 16-month-old twins and their parents. Found that additive genetic and shared environmental effects best represented smiling, laughter, and duration of orienting. Shared environmental effects fully accounted for co-twin similarity for soothability. Additive…

Three experiments used a familiarization/novelty or a habituation/dishabituation procedure to examine developmental change in infants' tendency to parse exemplars into separate categories. Results indicated that 10-month olds appeared to form differentiated categories, whereas 4- and 7-month olds formed a single category to include the range of…

This study examined how novel words foster the formation of object categories for 12- to 13-month olds. Results indicated that by 12 to 13 months, infants have begun to distinguish between novel words presented as count nouns versus adjectives in fluent, infant-directed speech, and that infants' expectations for novel words accord with this…

Two studies examined whether 1-year olds' name learning during joint attention was guided by expectation that names will be in the form of spoken words. Results showed that 13-month olds, but not 20-month olds, learned a new sound/object correspondence, as evidenced by their choosing targets reliably in responses to hearing the word or sound on…

Examined exogenous orienting among infants between 7 and 21 weeks of age in 2 experiments using display with multiple potential attention targets. Found that as early as 7 weeks of age, sensitivity for a small moving stimulus can be significantly influenced by the simultaneous presence of competing attention targets. Found large increases in…

Three experiments investigated use of visual input and body movement input arising from movement through the world on spatial orientation. Experiments involved infants searching for a toy hidden in one of two containers. Findings indicated that search was best after infant movement in a lit environment prior to searching; all other conditions led…

Six experiments examined infants' ability to associate nonsense words with two causal actions: pushing and pulling. Eighteen-month-olds, but not 14-month-olds, formed word-action associations. Fourteen-month-olds discriminated a change in label but not a change in action when the other was held constant. When language labels were replaced with…

Examined 8- to 10-month-olds' responses to standard procedures eliciting joy, fear, anger, and discomfort. Found that response parameters to standard procedures cohered strongly within each episode. Responses cohered across same-emotion episodes, except for anger. Responses and father-reported temperament related to infant's emotional tone in…

Two experiments examined 6-month olds' ability to categorize natural infant-directed utterances. Infants heard seven different tokens from one class of utterance (comforting, approving). Findings indicated that infants who later heard a test stimulus from the unfamiliar class showed response recovery, whereas those who heard a novel stimulus from…

Evaluated infants' ability to form new object categories based on either visual or naming information at 16 and 20 months using an object manipulation task. Found that infants at both ages showed evidence of using visual information to categorize the objects. Only 20-month-olds used naming information. Found a correlation between vocabulary size…

Two experiments examined 8-month-olds' use of absolute and relative pitch cues in a tone-sequence statistical learning task. Results suggest that, given unsegmented stimuli that do not conform to rules of musical composition, infants are more likely to track patterns of absolute pitches than of relative pitches. A third experiment found that adult…

Four-month-old infants from Boston, Dublin, and Beijing were administered the same battery of visual, auditory, and olfactory stimuli. The Chinese infants were significantly less active, irritable, and vocal than the Boston and Dublin samples, with American infants showing the highest level of reactivity. (Author)

Examined the effect of functional values of stimuli on orienting response elicitation. Subjects were 50 4-month-old infants and were randomly assigned to 1 of 3 experimental conditions. Results suggested the importance of taking into account the functional value of stimuli when analyzing infant attention. (MOK)

Examined whether 6-month-olds expect people to behave differently toward persons and inanimate objects. Found that infants habituated to an actor talking to something hidden behind an occluder looked longer at an object, whereas infants habituated to an actor reaching and swiping looked longer at a person. No difference in looking at stimuli was…

Examined representation of pictorial exemplars of humans by 3- and 4-month olds. Results demonstrated an asymmetry regarding the exclusivity of categorical representations formed for humans and non-human animals. Categorical representations for humans included exemplar information, whereas categorical representation for non-human animals was based…