Around the world,adolescence is a time of heightened sensation seeking and immature self‐regulation

The dual systems model of adolescent risk‐taking portrays the period as one characterized by a combination of heightened sensation seeking and still‐maturing self‐regulation, but most tests of this model have been conducted in the United States or Western Europe. In the present study, these propositions are tested in an international sample of more than 5000 individuals between ages 10 and 30 years from 11 countries in Africa, Asia, Europe and the Americas, using a multi‐method test battery that includes both self‐report and performance‐based measures of both constructs. Consistent with the dual systems model, sensation seeking increased between preadolescence and late adolescence, peaked at age 19, and declined thereafter, whereas self‐regulation increased steadily from preadolescence into young adulthood, reaching a plateau between ages 23 and 26. Although there were some variations in the magnitude of the observed age trends, the developmental patterns were largely similar across countries.     

Gesture for generalization: gesture facilitates flexible learning of words for actions on objects

Verb learning is difficult for children (Gentner, 1982 ), partially because children have a bias to associate a novel verb not only with the action it represents, but also with the object on which it is learned (Kersten & Smith, 2002 ). Here we investigate how well 4‐ and 5‐year‐old children (N = 48) generalize novel verbs for actions on objects after doing or seeing the action (e.g., twisting a knob on an object) or after doing or seeing a gesture for the action (e.g., twisting in the air near an object). We find not only that children generalize more effectively through gesture experience, but also that this ability to generalize persists after a 24‐hour delay.     

Proximodistal exploration in motor learning as an emergent property of optimization

To harness the complexity of their high‐dimensional bodies during sensorimotor development, infants are guided by patterns of freezing and freeing of degrees of freedom. For instance, when learning to reach, infants free the degrees of freedom in their arm proximodistally, that is, from joints that are closer to the body to those that are more distant. Here, we formulate and study computationally the hypothesis that such patterns can emerge spontaneously as the result of a family of stochastic optimization processes, without an innate encoding of a maturational schedule. In particular, we present simulated experiments with an arm where a computational learner progressively acquires reaching skills through adaptive exploration, and we show that a proximodistal organization appears spontaneously, which we denote PDFF (Proximo Distal Freezing and Freeing of degrees of freedom). We also compare this emergent organization between different arm morphologies—from human‐like to quite unnatural ones—to study the effect of different kinematic structures on the emergence of PDFF.     

Auditory‐motor adaptation is reduced in adults who stutter but not in children who stutter

Previous studies have shown that adults who stutter produce smaller corrective motor responses to compensate for unexpected auditory perturbations in comparison to adults who do not stutter, suggesting that stuttering may be associated with deficits in integration of auditory feedback for online speech monitoring. In this study, we examined whether stuttering is also associated with deficiencies in integrating and using discrepancies between expected and received auditory feedback to adaptively update motor programs for accurate speech production. Using a sensorimotor adaptation paradigm, we measured adaptive speech responses to auditory formant frequency perturbations in adults and children who stutter and their matched nonstuttering controls. We found that the magnitude of the speech adaptive response for children who stutter did not differ from that of fluent children. However, the adaptation magnitude of adults who stutter in response to auditory perturbation was significantly smaller than the adaptation magnitude of adults who do not stutter. Together these results indicate that stuttering is associated with deficits in integrating discrepancies between predicted and received auditory feedback to calibrate the speech production system in adults but not children. This auditory‐motor integration deficit thus appears to be a compensatory effect that develops over years of stuttering.     

Auditory access,language access,and implicit sequence learning in deaf children

Developmental psychology plays a central role in shaping evidence‐based best practices for prelingually deaf children. The Auditory Scaffolding Hypothesis (Conway et al., 2009) asserts that a lack of auditory stimulation in deaf children leads to impoverished implicit sequence learning abilities, measured via an artificial grammar learning (AGL) task. However, prior research is confounded by a lack of both auditory and language input. The current study examines implicit learning in deaf children who were (Deaf native signers) or were not (oral cochlear implant users) exposed to language from birth, and in hearing children, using both AGL and Serial Reaction Time (SRT) tasks. Neither deaf nor hearing children across the three groups show evidence of implicit learning on the AGL task, but all three groups show robust implicit learning on the SRT task. These findings argue against the Auditory Scaffolding Hypothesis, and suggest that implicit sequence learning may be resilient to both auditory and language deprivation, within the tested limits. A video abstract of this article can be viewed at: https://youtu.be/EeqfQqlVHLI [Correction added on 07 August 2017, after first online publication: The video abstract link was added.]     

What's parenting got to do with it: emotional autonomy and brain and behavioral responses to emotional conflict in children and adolescents

Healthy parenting may be protective against the development of emotional psychopathology, particularly for children reared in stressful environments. Little is known, however, about the brain and behavioral mechanisms underlying this association, particularly during childhood and adolescence, when emotional disorders frequently emerge. Here, we demonstrate that psychological control, a parenting strategy known to limit socioemotional development in children, is associated with altered brain and behavioral responses to emotional conflict in 27 at‐risk (urban, lower income) youth, ages 9–16. In particular, youth reporting higher parental psychological control demonstrated lower activity in the left anterior insula, a brain area involved in emotion conflict processing, and submitted faster but less accurate behavioral responses—possibly reflecting an avoidant pattern. Effects were not replicated for parental care, and did not generalize to an analogous nonemotional conflict task. We also find evidence that behavioral responses to emotional conflict bridge the previously reported link between parental overcontrol and anxiety in children. Effects of psychological control may reflect a parenting style that limits opportunities to practice self‐regulation when faced with emotionally charged situations. Results support the notion that parenting strategies that facilitate appropriate amounts of socioemotional competence and autonomy in children may be protective against social and emotional difficulties.     

Human milk cortisol concentration predicts experimentally induced infant fear reactivity: moderation by infant sex

Little consideration has been given to the possibility of human infant development being shaped via lactocrine programming, and by breast milk cortisol levels specifically. Despite animal models indicating that glucocorticoid (GC) exposure via lactation might modify brain development and behavior, only one study has reported that milk cortisol levels were positively associated with infant negative affectivity, especially fearfulness and sadness—early emerging risk factors for internalizing difficulties such as anxiety. The aim of the current study was to investigate whether human milk cortisol is associated with mother‐reported fearfulness and experimentally induced infant fear reactivity. Mother‐infant dyads (n = 65) enrolled in the FinnBrain Cohort Study participated. Breast milk samples were obtained 2.5 months postpartum, and milk cortisol concentrations were ascertained using validated luminescence immunoassay methodology. Infant fear reactivity was assessed using maternal reports 6 months postpartum and in a laboratory 8 months postpartum. There was a significant interaction between infant sex and milk cortisol such that higher milk cortisol was related to higher infant fear reactivity in a laboratory setting in girls (β = 0.36, p = .04) but not in boys (β = ?0.15, p = .40). Milk cortisol was not associated with mother‐reported infant fearfulness. Results suggest that higher human milk cortisol concentrations are associated with elevated experimentally induced fear in infancy. Findings support lactocrine programming, and suggest that mothers may “communicate” vital information about stressful environments via cortisol contained in breast milk, shaping girls' early emotional reactivity.     

Tool-use training temporarily enhances cognitive performance in long-tailed macaques (<Emphasis Type="Italic">Macaca fascicularis</Emphasis>)

Tool use relies on numerous cognitive functions, including sustained attention and understanding of causality. In this study, we investigated the effects of tool-use training on cognitive performance in primates. Specifically, we applied the Primate Cognition Test Battery to three long-tailed macaques (Macaca fascicularis) at different stages of a training procedure that consisted of using a rake to retrieve out-of-reach food items. In addition, we evaluated a control group (n?=?3) performing a grasping task, in order to account for possible effects related to a simple motor act. Our results showed that tool-use training enhances mean performance in the physical cognition domain, i.e. the understanding of spatial relations, numerosity and causality. In particular, causal cognition (evaluating noise- and shape-related causality and understanding of tool properties) showed significant improvement after training, whereas spatial cognition (evaluating spatial memory, object permanence, rotation and transposition) showed a trend to improvement. Despite these findings, none of our trained monkeys succeeded in the tool-use task of the Primate Cognition Test Battery, which involved an unfamiliar tool. Some training-related effects did not persist after a 35-day resting period, suggesting that continuous practice may be necessary, or that a longer training period before resting may be needed to better maintain cognitive performance. In contrast with the training group, the control group did not display any change in cognitive performance. This finding paves the way to further investigation into the link between tool-use behaviour and the evolution of primate cognition.     

Theory‐of‐Mind development and early sibling relationships after the birth of a sibling: Parental discipline matters

This study investigated relations among children's Theory‐of‐Mind (ToM) development, early sibling interactions, and parental discipline strategies during the transition to siblinghood. Using a sample of firstborn children and their parents (N = 208), we assessed children's ToM before the birth of a sibling and 12 months after the birth, and sibling interactions (i.e., positive engagement and antagonism) and parental discipline strategies (i.e., child‐centred and parent‐centred discipline) at 4 and 8 months in the first year of siblinghood. Structural equation modelling analyses revealed that children's ToM before the birth of the sibling predicted children's positive engagement with the infant sibling, whereas children's antagonistic behaviours towards the infant sibling negatively predicted children's ToM at 12 months, but only when mothers used low levels of child‐centred discipline. These findings emphasize the role of parents in the development of young children's social‐cognitive understanding in the context of early sibling interactions.

Highlights

• This study investigated relations among firstborns' Theory‐of‐Mind (ToM), early sibling relationships, and parental discipline during the first year of siblinghood.
• Multigroup analyses showed that ToM predicted higher sibling positive engagement, and early sibling antagonism predicted poorer ToM when mothers used low child‐centred discipline.
• Parental discipline plays an important role in the development of young children's social understanding and sibling relationships as early as the first year of siblinghood.