Human children copy others' actions with high fidelity, supporting early cultural learning and assisting in the development and maintenance of behavioral traditions [1]. Imitation has long been assumed to occur from birth [2-4], with influential theories (e.g., [5-7]) placing an innate imitation module at the foundation of social cognition (potentially underpinned by a mirror neuron system [8, 9]). Yet, the very phenomenon of neonatal imitation has remained controversial. Empirical support is mixed and interpretations are varied [10-16], potentially because previous investigations have relied heavily on cross-sectional designs with relatively small samples and with limited controls [17, 18]. Here, we report surprising results from the most comprehensive longitudinal study of neonatal imitation to date. We presented infants (n = 106) with nine social and two non-social models and scored their responses at 1, 3, 6, and 9 weeks of age. Longitudinal analyses indicated that the infants did not imitate any of the models, as they were just as likely to produce the gestures in response to control models as they were to matching models. Previous positive findings were replicated in limited cross-sections of the data, but the overall analyses confirmed these findings to be mere artifacts of restricted comparison conditions. Our results undermine the idea of an innate imitation module and suggest that earlier studies reporting neonatal imitation were methodologically limited.

Animal brains have evolved to predict outcomes of events in the immediate environment [1-5]. Adult humans are particularly adept at dealing with environmental uncertainty, being able to mentally represent multiple, even mutually exclusive versions of the future and prepare accordingly. This capacity is fundamental to many complex future-oriented behaviors [6, 7], yet little is known about when it develops in children [8] and whether it is shared with non-human animals [9]. Here we show that children become able to insightfully prepare for two mutually exclusive versions of an undetermined future event during the middle preschool years, whereas we find no evidence for such a capacity in a sample of chimpanzees and orangutans. We gave 90 preschool children and 8 great apes the opportunity to catch an item dropped into a forked tube with two bottom openings. Children's performance improved linearly across age groups (2, 2.5, 3, 3.5, and 4 years), with none of the youngest group but most of the oldest group spontaneously covering both openings the first time they prepared to catch the item. The apes performed like 2-year-olds on the first trial, with none of them covering both openings. Some apes and 2-year-olds eventually passed the task, but only in a manner consistent with trial-and-error learning. Our results reveal the developmental trajectory of a critical cognitive ability that allows humans to prepare for future uncertainty, and they also raise the possibility that this ability is not shared with other hominids.

Prominent theorists have made the argument that modern humans express moral concern for a greater number of entities than at any other time in our past. Moreover, adults show stable patterns in the degrees of concern they afford certain entities over others, yet it remains unknown when and how these patterns of moral decision-making manifest in development. Children aged 4 to 10 years (N = 151) placed 24 pictures of human, animal, and environmental entities on a stratified circle representing three levels of moral concern. Although younger and older children expressed similar overall levels of moral concern, older children demonstrated a more graded understanding of concern by including more entities within the outer reaches of their moral circles (i.e., they were less likely to view moral inclusion as a simple in vs. out binary decision). With age children extended greater concern to humans than other forms of life, and more concern to vulnerable groups, such as the sick and disabled. Notably, children’s level of concern for human entities predicted their prosocial behavior. The current research provides novel insights into the development of our moral reasoning and its structure within childhood.

Episodic foresight is the future-directed counterpart of episodic memory. It is a sophisticated, potentially uniquely human capacity, with tremendous adaptive consequences. Here we review what is currently known about its development through early childhood. We tackle this from two distinct perspectives. First, we present the first systematic evaluation of the development of purported components of mental scenario building as highlighted by a theater metaphor: the stage, the playwright, the set, the actors, the director, the executive producer, and the broadcaster. We find that, although there are diverse developmental trajectories, by 4 years of age children have acquired the basic cognitive components required to mentally construct specific future events. Second, we examine recent attempts to test children's episodic foresight more directly and find that results are in line with those examining the development of required components. This is not to say that children younger than four have no inkling of upcoming events or that older children have nothing left to learn about constructing the future. Episodic foresight, and its neurocognitive foundations, continues to develop throughout childhood.

The author has declared no conflicts of interest for this article.