Developmental Science

Maternal cortisol levels (at 15, 19, 25, 31 and 37 weeks’ gestation) and fetal movement response to vibroacoustic stimulation (VAS; at 25, 31 and 37 weeks) were assessed in 190 mother-fetus pairs. Fetuses showed a response to the VAS at 25 weeks and there was evidence of increasing maturation in the response at 31 and 37 weeks. Early elevations in cortisol predicted a failure to respond to the VAS at 25 weeks and later elevations in cortisol were associated with a larger response among fetuses when assessed near term.

Many studies have converged on the view that infant pointing reflects a motivation to share attention and interest with others. We tested a hypothesis in which the goal of pointing is not attention sharing itself, but the information-laden response that infants tend to receive as a result of sharing attention. Our results suggest that one function of pointing in infancy is to obtain information from others, and that infants selectively elicit desired information from those who they perceive could competently provide it.

Theory of mind requires belief- and desire-understanding. Event-related brain potential (ERP) research on belief- and desire-reasoning in adults found mid-frontal activations for both desires and beliefs, and selective right-posterior activations only for beliefs. Developmentally, children understand desires before beliefs; thus, a critical question concerns whether neural specialization for belief-reasoning exists in childhood or develops later. Neural activity was recorded as 7- and 8-year-olds (N = 18) performed the same diverse-desires, diverse-beliefs, and physical control tasks used in a previous adult ERP study.

Based on anticipatory looking and reactions to violations of expected events, infants have been credited with ‘theory of mind’ (ToM) knowledge that a person’s search behaviour for an object will be guided by true or false beliefs about the object’s location. However, little is known about the preconditions for looking patterns consistent with belief attribution in infants. In this study, we compared the performance of 17- to 26-month-olds on anticipatory looking in ToM tasks. The infants were either hearing or were deaf from hearing families and thus delayed in communicative experience gained from access to language and conversational input. Hearing infants significantly outperformed their deaf counterparts in anticipating the search actions of a cartoon character that held a false belief about a target-object location.

As with all culturally relevant human behaviours, words are meaningful because they are shared by the members of a community. This research investigates whether 9-month-old infants understand this fundamental fact about language. Experiment 1 examined whether infants who are trained on, and subsequently habituated to, a new word–referent link expect the link to be consistent across a second speaker. Experiment 2 examined whether 9-month-old infants distinguish between behaviours that are shared across individuals (i.e. words) from those that are not (i.e. object preferences).

The functional distinction between vision for perception and vision for action is well documented in the mature visual system. Ganel and colleagues recently provided direct evidence for this dissociation, showing that while visual processing for perception follows Weber’s fundamental law of psychophysics, action violates this law. We tracked the developmental trajectory of this functional dissociation, asking whether the qualitatively different pattern observed in adults of adherence of perception but not of action to Weber’s law would also be evident early in life.

Theories of language acquisition have highlighted the importance of adult speakers as active participants in children’s language learning. However, in many communities children are reported to be directly engaged by their caregivers only rarely (Lieven, 1994). This observation raises the possibility that these children learn language from observing, rather than participating in, communicative exchanges. In this paper, we quantify naturally occurring language input in one community where directed interaction with children has been reported to be rare (Yucatec Mayan). We compare this input to the input heard by children growing up in large families in the United States, and we consider how directed and overheard input relate to Mayan children’s later vocabulary.

Although the acquisition of a novel word is apparently rapid, adult research suggests that integration of novel and existing knowledge (measured by engagement in lexical competition) requires sleep-associated consolidation. We present the first investigation of whether a similar time-course dissociation characterizes word learning across development. We found that novel nonwords only induced lexical competition effects for 7–12 year olds after sleep. These findings suggest that children utilize a dual memory system when acquiring and integrating new vocabulary and highlight sleep as integral to this process.

We live in a world rich in sensory information, and consequently the brain is challenged with deciphering which cues from the various sensory modalities belong together. Determinations regarding the relatedness of sensory information appear to be based, at least in part, on the spatial and temporal relationships between the stimuli. Stimuli that are presented in close spatial and temporal correspondence are more likely to be associated with one another and thus ‘bound’ into a single perceptual entity.

Recent research has considered the phonological specificity of children’s word representations, but few studies have examined the flexibility of those representations. Tolerating acoustic–phonetic deviations has been viewed as a negative in terms of discriminating minimally different word forms, but may be a positive in an increasingly multicultural society where children encounter speakers with variable accents. Here, 3-5-year-olds showed fairly accurate but slowed recognition of accent-like pronunciations.

Human infants readily interpret others’ actions as goal-directed and their understanding of previous goals shape their expectations about an agent’s future goal-directed behavior in a changed situation. According to a recent proposal (Luo & Baillargeon, 2005), infants’ goal-attributions are not sufficient to support such expectations if the situational change involves broadening the set of choice-options available to the agent, and the agent’s preferences among this broadened set are not known. The present study falsifies this claim.

This commentary article is to be published alongside: Hernik, M., & Southgate, V. (2012). Nine-months-old infants do not need to know what the agent prefers in order to reason about its goals: on the role of preference and persistence in infants’ goal-attribution. Developmental Science. doi/10.1111/j.1467-7687.2012.01151.x

This commentary article is to be published alongside: Hernik, M., & Southgate, V. (2012). Nine-months-old infants do not need to know what the agent prefers in order to reason about its goals: on the role of preference and persistence in infants’ goal-attribution. Developmental Science. doi/10.1111/j.1467-7687.2012.01151.x

This commentary article is to be published alongside: Hernik, M., & Southgate, V. (2012). Nine-months-old infants do not need to know what the agent prefers in order to reason about its goals: on the role of preference and persistence in infants’ goal-attribution. Developmental Science. doi/10.1111/j.1467-7687.2012.01151.x

This reply article is to be published alongside: Hernik, M., & Southgate, V. (2012). Nine-months-old infants do not need to know what the agent prefers in order to reason about its goals: on the role of preference and persistence in infants’ goal-attribution. Developmental Science. doi/10.1111/j.1467-7687.2012.01151.x