The still-face response in newborn, 1.5-, and 3-month-old infants

The present study investigated the still-face response to a female stranger in newborn, 1.5-, and 3-month-old infants. The results revealed that 1.5- and 3-month-olds, but not newborns, reliably decreased their visual attention and positive affect when the interaction partner became unresponsive during the still-face period.     

Is visual reference necessary? Contributions of facial versus vocal cues in 12‐month‐olds’ social referencing behavior

To examine the influences of facial versus vocal cues on infants' behavior in a potentially threatening situation, 12-month-olds on a visual cliff received positive facial-only, vocal-only, or both facial and vocal cues from mothers. Infants' crossing times and looks to mother were assessed. Infants crossed the cliff faster with multimodal and vocal than with facial cues, and looked more to mother in the Face Plus Voice compared to the Voice Only condition. The findings suggest that vocal cues, even without a visual reference, are more potent than facial cues in guiding infants' behavior. The discussion focuses on the meaning of infants' looks and the role of voice in development of social cognition.     

Symmetry training in pigeons can produce functional equivalences

Functional stimulus equivalence has been demonstrated using a transfer of training design with matching-to-sample training in which two sample stimuli are associated with the same comparison stimulus (A-B, C-B; many-to-one matching). Equivalence is shown by training a new association (A-D) and demonstrating the presence of an emergent relation (C-D). In the present experiment, we show that symmetry training, in which a bidirectional association is trained between two stimuli (A-B, B-A, using successive stimulus presentations followed by reinforcement), can also produce functional equivalence using a transfer of training design (i.e., train B-C, test A-C). The results suggest that training pigeons in the substitutability of two stimuli may be sufficient to produce functional stimulus equivalence between them. The results also have implications for the development of an emergent transitive relation, because training on A-B and B-C relations results in the emergence of an untrained A-C relation, if B-A training also is provided.     

Choice based on exclusion in pigeons

When humans acquire a conditional discrimination and are given a novel-sample-comparison choice, they often reject a comparison known to be associated with a different sample and choose the alternative comparison by default (or by exclusion). In Experiment 1, we found that if, following matching training, we replaced both of the samples, acquisition took five times longer than if we replaced only one of the samples. Apparently, the opportunity to reject one of the comparisons facilitated the association of the other sample with the remaining comparison. In Experiment 2, we first trained pigeons to treat two samples differently (to associate Sample A with Comparison 1 and Sample B with Comparison 2) and then trained them to associate one of those samples with a new comparison (e.g., Sample A with Comparison 3) and to associate a novel sample (Sample C) with a different, new comparison (Comparison 4). When Sample B then replaced Sample C, the pigeons showed a significant tendency to choose Comparison 4 over Comparison 3. Thus, when given the opportunity, pigeons will choose by exclusion.     

Perceived self in infancy

Research is presented suggesting that an implicit sense of self is developing from birth, long before children begin to manifest explicit (conceptual) self-knowledge by the second year. Implicit self-knowledge in infancy is rooted in intermodal perception and action. Studies are reported showing that at least from 2 months of age, infants become increasingly systematic and deliberate in the exploration of their own body and the perceptual consequences of self-produced action. From such exploration, infants develop a sense of their own body as a differentiated entity, situated and agent in the environment. Based on recent empirical findings, the perceptual determinants of such implicit sense of self are discussed.     

Infant’s gaze in a teasing task with an experimenter or parent: A naturalistic approach

We assessed infant’s gaze in a teasing task in New York City public spaces. The task was administered to two different groups of 5- to 13-month-old infants. We used a between participants design across two studies. In Study 1 an experimenter administered the task to these infants (n = 79), whereas a parent did so in Study 2 (n = 79). The adult engaged the infant with a toy and then pulled it away to one side by counting to 7. A second trial to the other side was repeated. Infants passed the teasing task if they looked to the adult’s face within the first 5 seconds after removing the toy in at least one trial. In Study 1, we found that infants looked to the experimenter’s face after teasing by 7 months of age. In Study 2, infants did not show any significant gazes to the parent’s face after teasing at any age. Most trained parents successfully administered the teasing task to their infant. A teasing game played by an adult stranger (e.g., experimenter) may be optimal to elicit infant’s gaze in a naturalistic setting. Implications for developing cost-effective social-cognitive milestone measures in non-laboratory settings are discussed.     

On tools and toys: how children learn to act on and pretend with 'virgin objects'

The focus of the present study was the role of cultural learning in infants' acquisition of pretense actions with objects. In three studies, 18- and 24-month-olds (n = 64) were presented with novel objects, and either pretense or instrumental actions were demonstrated with these. When children were then allowed to act upon the objects themselves, qualitatively similar patterns of cultural (imitative) learning both of pretend and of instrumental actions were observed, suggesting that both types of actions can be acquired in similar ways through processes of cultural learning involving one or another form of collective intentionality. However, both absolute imitation rates and creativity were lower in pretense compared to instrumental actions, suggesting that the collective intentionality that constitutes pretense is especially difficult for children to comprehend. An additional analysis of children's gazes to the experimenter during their actions revealed that 24-month-olds looked more often to the experimenter during pretense actions than during instrumental actions - suggesting that pretense is culturally learned in a similar fashion as practical actions, but that young children understand pretense as a more inherently social, intersubjective activity.     

The effects of joint attention on object processing in 4- and 9-month-old infants

In this study, we examined the effects of joint attention on object processing in 4- and 9-month-old infants. An adult experimenter differed social cues while speaking to infants about a novel object. Only 9-month-olds showed evidence of enhanced object processing following a joint attention interaction.     

Developmental changes in infants' processing of happy and angry facial expressions: a neurobehavioral study

Event-related brain potentials were measured in 7- and 12-month-old infants to examine the development of processing happy and angry facial expressions. In 7-month-olds a larger negativity to happy faces was observed at frontal, central, temporal and parietal sites (Experiment 1), whereas 12-month-olds showed a larger negativity to angry faces at occipital sites (Experiment 2). These data suggest that processing of these facial expressions undergoes development between 7 and 12 months: while 7-month-olds exhibit heightened sensitivity to happy faces, 12-month-olds resemble adults in their heightened sensitivity to angry faces. In Experiment 3 infants' visual preference was assessed behaviorally, revealing that the differences in ERPs observed at 7 and 12 months do not simply reflect differences in visual preference.