Instrumental and Conventional Interpretations of Behavior Are Associated With Distinct Outcomes in Early Childhood

Do children imitate even when it is costly? New insights from a novel task

Children have a proclivity to learn through faithful imitation, but the extent to which this applies under significant cost remains unclear. To address this, we investigated whether 4- to 6-year-old children (N = 97) would stop imitating to forego a desirable food reward. We presented participants with a task involving arranging marshmallows and craft sticks, with the goal being either to collect marshmallows or build a tower. Children replicated the demonstrated actions with high fidelity regardless of the goal, but retrieved rewards differently. Children either copied the specific actions needed to build a tower, prioritizing tower completion over reward; or adopted a novel convention of stacking materials before collecting marshmallows, and developed their own method to achieve better outcomes. These results suggest children's social learning decisions are flexible and context-dependent, yet that when framed by an ostensive goal, children imitated in adherence to the goal despite incurring significant material costs.

Toddlers do not preferentially transmit generalizable information to others

Children actively and selectively transmit information to others based on the type of information and the context during learning. Four- to 7-year-old children preferentially transmit generalizable information in teaching-like contexts. Although 2-year-old children are able to distinguish between generalizable and non-generalizable information, it is not known whether they likewise transmit generalizable information selectively. We designed a behavioral study to address this question. Two-year-old children were presented with three novel boxes, identical except for their color. In each box, one of two equally salient actions led to a generalizable outcome (e.g., playing a [different] tune in each box), whereas the other led to a non-generalizable outcome (e.g., turning on a light, vibrating the box, or making a noise). In the discovery phase, children had a chance to discover the functions of each box presented one-by-one. Then, in the exploration phase, they were given the opportunity to independently explore all three boxes presented together. Finally, in the transmission phase, an ignorant recipient entered the room and asked the child to show them how these toys work. We measured whether children preferentially transmitted either generalizable or non-generalizable information when they were asked to demonstrate the function of the toys to a naïve adult. We found that children did not display any preference for transmitting generalizable information. These findings are discussed with respect to toddlers' selectivity in transmitting information but also the development of sensitivity to information generalizability. RESEARCH HIGHLIGHT: Young children transmit information to others and do so with some degree of selectivity to a variety of factors. Generalizability is an important factor affecting information transmission, and older children tend to associate generalizable information with teaching-like interactions. We tested whether toddlers selectively transmitted it to others over non-generalizable information. We found that toddlers do not show a preference to transmit generalizable over non-generalizable information.

Children's distinct drive to reproduce costly rituals

Costly rituals are ubiquitous and adaptive. Yet, little is known about how children develop to acquire them. The current study examined children's imitation of costly rituals. Ninety-three 4-6 year olds (47 girls, 45% Oceanians, tested in 2022) were shown how to place tokens into a tube to earn stickers, using either a ritualistic or non-ritualistic costly action sequence. Children shown the ritualistic actions imitated faithfully at the expense of gaining stickers; conversely, those shown the non-ritualistic actions ignored them and obtained maximum reward. This highlights how preschool children are adept at and motivated to learn rituals, despite significant material cost. This study provides insights into the early development of cultural learning and the adaptive value of rituals in group cognition.

The effects of model age and familiarity on children's reproduction of ritual behaviour

Rituals are fundamental social acts that structure relationships and enable the filtering of important cognitive attributes (e.g. working memory and inhibitory control) that make humans what they are today. This study investigated the influence of model age and familiarity on the reproduction of ritual behaviour in five-year-old children. Through an exploration of these factors, this study sheds light on the cognitive mechanisms children use to comprehend and replicate rituals. Ninety-eight five-year-old children were divided into two groups: an experimental group, which observed an adult or child model, either familiar or unfamiliar to them, demonstrating eight ritual acts; and a control group, which received no video demonstration. The results revealed that children who observed an adult reproduced more ritual acts than those who observed a child, and children who observed unfamiliar models reproduced ritual acts more frequently than those who observed familiar ones. Additionally, when exposed to unfamiliar models, children's reproductive fidelity was higher. These findings suggest that children have the ability to address new adaptation challenges by participating in rituals at an early age and that they generate suitable solutions depending on the model's characteristics. This provides evidence for the adaptive bias in children's cultural learning from a ritual perspective.

Ordinality and Verbal Framing Influence Preschoolers' Memory for Spatial Structure

During the preschool years, children are simultaneously undergoing a reshaping of their mental number line and becoming increasingly sensitive to the social norms expressed by those around them. In the current study, 4- and 5-year-old American and Israeli children were given a task in which an experimenter laid out chips with numbers (1-5), letters (A-E), or colors (Red-Blue, the first colors of the rainbow), and presented them with a specific order (initial through final) and direction (Left-to-right or Right-to-left). The experimenter either did not demonstrate the laying out of the chips (Control), emphasized the process of the left-to-right or right-to-left spatial layout (Process), or used general goal language (Generic). Children were then asked to recreate each sequence after a short delay. Children also completed a short numeracy task. The results indicate that attention to the spatial structuring of the environment was influenced by conventional framing; children exhibited better recall when the manner of layout was emphasized than when it was not. Both American and Israeli children were better able to recall numerical information relative to non-numerical information. Although children did not show an overall benefit for better recall of information related to the culture's dominant spatial direction, American children's tendency to recall numerical direction information predicted their early numeracy ability.

Bifocal stance theory: An effort to broaden, extend, and clarify

The bifocal stance theory (BST) of cultural evolution has prompted a wide-ranging discussion with broadly three aims: to apply the theory to novel contexts; to extend the conceptual framework; to offer critical feedback on various aspects of the theory. We first discuss BST's relevance to the diverse range of topics which emerged from the commentaries, followed by a consideration of how our framework can be supplemented by and compared to other theories. Lastly, the criticisms that were raised by a subset of commentaries allow us to clarify parts of our theory.

The ontogeny of selective social learning: Young children flexibly adopt majority- or payoff-based biases depending on task uncertainty

Humans have adapted well to diverse environments in part because of their ability to efficiently acquire information from their social environment. However, we still know very little as to how young children acquire cultural knowledge and in particular the circumstances under which children prioritize social learning over asocial learning. In this study, we asked whether children will selectively adopt either a majority-biased or payoff-biased social learning strategy in the presence or absence of asocial learning. The 3- to 5-year-olds (N = 117) were first shown a video in which four other children took turns in retrieving a capsule housing a reward from one of two boxes. Three of the children (the "majority") retrieved a capsule from the same box, and a single individual (the "minority") retrieved a capsule from the alternative box. Across four conditions, we manipulated both the value of the rewards available in each box (equal or unequal payoff) and whether children had knowledge of the payoff before making their own selection. Results show that children adopted a majority-biased learning strategy when they were unaware of the value of the rewards available but adopted a payoff-biased strategy when the payoff was known to be unequal. We conclude that children are strategic social learners who integrate both social and asocial learning to maximize personal gain.

If I told you everyone picked that (non-affordant) tool, would you? Children attend to conventional language when imitating and transmitting tool use

This study explored how conventional versus instrumental language influenced children's imitation and transmission of non-affordant tool use. Rather than examining children's imitation of unnecessary actions that do not impede goal completion, we examined children's conformity with a modeled behavior that may result in sacrificing goal completion. Children (N = 96 4- to 6-year-olds) were presented with either a conventional or instrumental description of a model's actions before watching the model choose a non-affordant tool. Children who heard conventional language imitated and transmitted the model's non-affordant tool choice at significantly higher rates than when they heard instrumental language. The results have implications for children, parents, and teachers regarding the extent to which children will conform with what "we" are "supposed" to do.

Spreading the game: An experimental study on the link between children's overimitation and their adoption, transmission, and modification of conventional information

Overimitation is hypothesized to foster the spread of conventional information within populations. The current study tested this claim by assigning 5-year-old children (N = 64) to one of two study populations based on their overimitation (overimitators [OIs] vs. non-overimitators [non-OIs]). Children were presented with conventional information in the form of novel games lacking instrumental outcomes, and we observed children's adoption, transmission, and modification of this information across two study phases. Results reveal little variation across study populations in the number of game elements that were adopted and transmitted. However, OIs were more likely to use normative language than non-OIs when transmitting game information to their peers. Furthermore, non-OIs modified the games more frequently in the initial study phase, suggesting an inverse relationship between children's overimitation and their tendency to modify conventional information. These findings indicate subtle yet coherent links between children's overimitation and their tendency to transmit and modify conventional information.

When does it pay to follow the crowd? Children optimize imitation of causally irrelevant actions performed by a majority

Cultural evolutionary theory posits that human cultural complexity rests on a set of adaptive learning biases that help to guide functionality and optimality in social learning, but this sits in contrast with the commonly held view that children are unselective "over-imitators." Here, we tested whether 4- and 6-year-old children use social learning biases flexibly to fine-tune their copying of irrelevant actions. Children watched a video of a majority demonstrating causally irrelevant actions and a minority demonstrating only causally relevant actions. In one condition observers approved of the majority and disapproved of the minority, and in the other condition observers watched the majority and minority neutrally. Results showed that both 4- and 6-year-olds copied the inefficient majority more often than the efficient minority when the observers had approved of the majority's actions, but they copied the efficient minority significantly more when the observers had watched neutrally. We discuss the implications of children's optimal selectivity in copying and the importance of integrating social approval into majority-biased learning when acquiring norms and conventions and in broader processes of cultural evolution.

Personality predicts innovation and social learning in children: Implications for cultural evolution

Innovation and social learning are the pillars of cultural evolution, allowing cultural behaviours to cumulatively advance over generations. Yet, little is known about individual differences in the use of social and asocial information. We examined whether personality influenced 7-11-year-old children's (N = 282) propensity to elect to observe others first or independently generate solutions to novel problems. Conscientiousness was associated with electing for no demonstrations, while agreeableness was associated with opting for demonstrations. For children receiving demonstrations, openness to experience consistently predicted deviation from observed methods. Children who opted for no demonstrations were also more likely than those opting for demonstrations to exhibit tool manufacture on an innovation challenge and displayed higher creativity, as measured by an alternate uses task. These results highlight how new cultural traditions emerge, establish and advance by identifying which individuals generate new cultural variants in populations and which are influential in the diffusion of these variants, and help reduce the apparent tension within the 'ratchet' of cumulative culture.

Carry-over effects of tool functionality and previous unsuccessfulness increase overimitation in children

Children 'overimitate' causally irrelevant actions in experiments where both irrelevant and relevant actions involve a single common tool. This study design may make it harder for children to recognize the irrelevant actions, as the perceived functionality of the tool during the demonstration of the relevant action may be carried over to the irrelevant action, potentially increasing overimitation. Moreover, little is known how overimitation is affected by the demonstrator's expressed emotions and the child's prior success with the task. Here, 131 nine- to ten-year-old French and German children first engaged in a tool-based task, being successful or unsuccessful, and then watched an adult demonstrating the solution involving one irrelevant and one relevant action before smiling or remaining neutral. These actions were performed with the same tool or with two separate tools, testing potential carry-over effects of the functionality of the relevant action on the irrelevant action. We show that overimitation was higher when the same tool was used for both actions and when children were previously unsuccessful, but was not affected by the demonstrator's displayed emotion. Our results suggest that future overimitation research should account for the number of tools used in a demonstration and participants' previous task experience.

Young children conform more to norms than to preferences

As members of cultural groups, humans continually adhere to social norms and conventions. Researchers have hypothesized that even young children are motivated to act conventionally, but support for this hypothesis has been indirect and open to other interpretations. To further test this hypothesis, we invited 3.5-year-old children (N = 104) to help set up items for a tea party. Children first indicated which items they preferred but then heard an informant (either an adult or another child) endorse other items in terms of either conventional norms or personal preferences. Children conformed (i.e., overrode their own preference to follow the endorsement) more when the endorsements were framed as norms than when they were framed as preferences, and this was the case whether the informant was an adult or another child. The priority of norms even when stated by another child opposes the interpretation that children only conformed in deference to adult authority. These findings suggest that children are motivated to act conventionally, possibly as an adaptation for living in cultural groups.

Ecological and Developmental Perspectives on Social Learning : Introduction to the Special Issue

In this special issue of Human Nature we explore the possible adaptive links between teaching and learning during childhood, and we aim to expand the dialogue on the ways in which the social sciences, and in particular current anthropological research, may better inform our shifting understanding of how these processes vary in different social and ecological environments. Despite the cross-disciplinary trend toward incorporating more behavioral and cognitive data outside of postindustrial state societies, much of the published cross-cultural data is presented as stand-alone population-level studies, making it challenging to extrapolate trends or incorporate both ecological and developmental perspectives. Here, contributors explore how human life history, ecological experience, cumulative culture, and ethnolinguistics impact social learning and child development in foraging and transitioning societies around the world. Using historical ethnographic data and qualitative and quantitative data from studies with contemporary populations, authors interrogate the array of factors that likely interact with cognitive development and learning. They provide contributions that explore the unique environmental, social, and cultural conditions that characterize such populations, offering key insights into processes of social learning, adaptive learning responses, and culture change. This series of articles demonstrates that children are taught culturally and environmentally salient skills in myriad ways, ranging from institutionalized instruction to brief, nuanced, and indirect instruction. Our hope is that this collection stimulates more research on the evolutionary and developmental implications associated with teaching and learning among humans.

Watch me, watch you: ritual participation increases in-group displays and out-group monitoring in children

Collective rituals serve social functions for the groups that perform them, including identifying group members and signalling group commitment. A novel social group paradigm was used in an afterschool programme (N = 60 4-11-year-olds) to test the influence of participating in a ritual task on in-group displays and out-group monitoring over repeated exposures to the group. The results demonstrate that ritual participation increases in-group displays (i.e. time spent displaying materials to in-group members) and out-group monitoring (i.e. time spent looking at out-group members) compared with a control task across three time points. This study provides evidence for the processes by which rituals may influence children's behaviours towards in- and out-group members and discusses implications for understanding the development of ritual cognition and behaviour. This article is part of the theme issue 'Ritual renaissance: new insights into the most human of behaviours'.

A cross-cultural investigation of young children's spontaneous invention of tool use behaviours

Through the mechanisms of observation, imitation and teaching, young children readily pick up the tool using behaviours of their culture. However, little is known about the baseline abilities of children's tool use: what they might be capable of inventing on their own in the absence of socially provided information. It has been shown that children can spontaneously invent 11 of 12 candidate tool using behaviours observed within the foraging behaviours of wild non-human apes (Reindl et al. 2016 Proc. R. Soc. B 283, 20152402. (doi:10.1098/rspb.2015.2402)). However, no investigations to date have examined how tool use invention in children might vary across cultural contexts. The current study investigated the levels of spontaneous tool use invention in 2- to 5-year-old children from San Bushmen communities in South Africa and children in a large city in Australia on the same 12 candidate problem-solving tasks. Children in both cultural contexts correctly invented all 12 candidate tool using behaviours, suggesting that these behaviours are within the general cognitive and physical capacities of human children and can be produced in the absence of direct social learning mechanisms such as teaching or observation. Children in both cultures were more likely to invent those tool behaviours more frequently observed in great ape populations than those less frequently observed, suggesting there is similarity in the level of difficulty of invention across these behaviours for all great ape species. However, children in the Australian sample invented tool behaviours and succeeded on the tasks more often than did the Bushmen children, highlighting that aspects of a child's social or cultural environment may influence the rates of their tool use invention on such task sets, even when direct social information is absent.

Acquiring sub-efficient and efficient variants of novel means by integrating information from multiple social models in preschoolers

Sub-efficient action routines often represent culture-specific conventional forms of actions that belong to the repertoire of cultural knowledge shared by a social group. Children readily acquire such sub-efficient routines from social demonstrations and often preserve them in their action repertoire despite encountering more efficient alternatives. This suggests that they can treat sub-efficient conventional forms and their efficient alternatives in a context-sensitive selective manner. We hypothesized that children may rely on their sensitivity to differentiate speakers of their own language versus a foreign language as an informative cue indicating whether the model belongs to their own cultural community and the action modeled represents shared cultural knowledge. We assessed preschoolers' imitation following two different demonstrations. The first model demonstrated a sub-efficient action sequence, whereas the second model presented a more efficient alternative to obtain the same goal. We varied whether the children had heard the models speak their own language or a foreign language before their nonverbal action demonstrations. We found that 4-year-olds adopted the second model's efficient alternative, but only when she spoke their own language. However, they disregarded the efficient alternative if it was presented by a foreign-language speaker and continued to perform the sub-efficient routine they initially acquired. Therefore, 4-year-olds employed the cue of shared language to optimize acquiring and maintaining culturally shared sub-efficient action routines by selectively updating their action repertoire relying on their language-based evaluation of the demonstrator's culture-specific competence. In contrast, 5- and 6-year-olds adopted the efficient alternative independently of the demonstrator's language. Possible reasons for this developmental trend are discussed.

A model's natural group membership affects over-imitation in 6-year-olds

The phenomenon of "over-imitation"-the copying of causally irrelevant actions-has influenced research of the past decade. Yet, the mechanisms underlying and factors affecting over-imitation are still under debate. This study aimed to contribute to this debate by investigating the role of the model's natural group membership in children's tendency to imitate irrelevant actions using a two-phase design. In Phase 1, 6-year-olds (N = 64) observed either an in-group model or an out-group model presenting a sequence of irrelevant actions, with only the last action bringing about the goal (target action) and retrieving a token. In Phase 2, the alternative model-the one that children had not seen in Phase 1-retrieved the token by performing the target action only. After the presentation in each phase, children were given the chance to retrieve the token themselves. Results indicated that children imitated the irrelevant actions to comparable levels from both models in Phase 1. In Phase 2, in contrast, over-imitation declined in children who observed the in-group model being successful with the target action only but not in children who observed the out-group model do so. Thus, children adapted their imitative behavior after observing the model of their own cultural group demonstrating a more efficient strategy. These findings speak for an integration of both social and instrumental accounts to explain the phenomenon of over-imitation.

The Development of Cumulative Cultural Learning

Human culture is unique among animals in its complexity, variability, and cumulative quality. This article describes the development and diversity of cumulative cultural learning. Children inhabit cultural ecologies that consist of group-specific knowledge, practices, and technologies that are inherited and modified over generations. The learning processes that enable cultural acquisition and transmission are universal but are sufficiently flexible to accommodate the highly diverse cultural repertoires of human populations. Children learn culture in several complementary ways, including through exploration, observation, participation, imitation, and instruction. These methods of learning vary in frequency and kind within and between populations due to variation in socialization values and practices associated with specific educational institutions, skill sets, and knowledge systems. The processes by which children acquire and transmit the cumulative culture of their communities provide unique insight into the evolution and ontogeny of human cognition and culture.

Smart Conformists: Children and Adolescents Associate Conformity With Intelligence Across Cultures

The current study used a novel methodology based on multivocal ethnography to assess the relations between conformity and evaluations of intelligence and good behavior among Western (U.S.) and non-Western (Ni-Vanuatu) children (6- to 11-year-olds) and adolescents (13- to 17-year-olds; N = 256). Previous research has shown that U.S. adults were less likely to endorse high-conformity children as intelligent than Ni-Vanuatu adults. The current data demonstrate that in contrast to prior studies documenting cultural differences between adults' evaluations of conformity, children and adolescents in the United States and Vanuatu have a conformity bias when evaluating peers' intelligence and behavior. Conformity bias for good behavior increases with age. The results have implications for understanding the interplay of conformity bias and trait psychology across cultures and development.

Four- and 5-Year-Olds Infer Differences in Relative Ability and Appropriately Allocate Roles to Achieve Cooperative, Competitive, and Prosocial Goals

Preschoolers are sensitive to differences in individuals’ access to external resources (e.g., tools) in division of labor tasks. However, little is known about whether children consider differences in individuals’ internal resources (e.g., abilities) and whether children can flexibly allocate roles across different goal contexts. Critically, factors that are relevant to role allocation in collaborative contexts may be irrelevant in competitive and prosocial ones. In three preregistered experiments, we found that 4- and 5-year-olds (mean: 54 months; range: 42–66 months; N = 132) used age differences to infer relative ability and appropriately allocate the harder and easier of two tasks in a dyadic cooperative interaction (Experiment 1), and appropriately ignored relative ability in competitive (Experiment 2) and prosocial (Experiment 3) contexts, instead assigning others the harder and easier roles, respectively. Thus, 3-and-a-half- to 5-year-olds evaluate their own abilities relative to others and effectively allocate roles to achieve diverse goals.

An experimental examination of object-directed ritualized action in children across two cultures

Ritualized actions are common in daily life, and prevalent across cultures. Adults have been shown, under experimental conditions, to treat objects subjected to ritualized action as special and different relative to objects subjected to non-ritualized action. Similarly, children as young as 4, are sensitive to ritualized actions–frequently reproducing such actions at high fidelity. The current cross-cultural experiment attempts to extend existing findings among two culturally distinct groups of children with regard to object-directed rituals. We predicted that children’s preference for a reward would be influenced by ritualized action (but not non-ritualized action). Over two trials we presented children in Australia (N = 93; mean age = 6.03 years, SD = 2.07 years) and Vanuatu (N = 109; mean age = 6.13 years, SD = 1.96 years) with two identical rewards, which was either subjected to ritualized action or non-ritualized action. Contrary to previous findings among adults, ritualized action did not influence children’s preference for a reward. We frame the current results in the context of socially relevant group rituals, and discuss the implications for both wider theory and methods. We conclude with a call for pre-registered replications.

The Rationality of (Over)imitation

Imitation is a powerful and ubiquitous social learning strategy, fundamental for the development of individual skills and cultural traditions. Recent research on the cognitive foundations and development of imitation, though, presents a surprising picture: Although even infants imitate in selective, efficient, and rational ways, children and adults engage in overimitation. Rather than imitating selectively and efficiently, they sometimes faithfully reproduce causally irrelevant actions as much as relevant ones. In this article, we suggest a new perspective on this phenomenon by integrating established findings on children’s more general capacities for rational action parsing with newer findings on overimitation. We suggest that overimitation is a consequence of children’s growing capacities to understand causal and social constraints in relation to goals and that it rests on the human capacity to represent observed actions simultaneously on different levels of goal hierarchies.

Cultural transmission in an ever-changing world: trial-and-error copying may be more robust than precise imitation

Cultural transmission facilitates the spread of behaviours within social groups and may lead to the establishment of stable traditions in both human and non-human animals. The fidelity of transmission is frequently emphasized as a core component of cultural evolution and as a prerequisite for cumulative culture. Fidelity is often considered a synonym of precise copying of observed behaviours. However, while precise copying guarantees reliable transmission in an ideal static world, it may be vulnerable to realistic variability in the actual environment. Here, we argue that fidelity may be more naturally achieved when the social learning mechanisms incorporate trial-and-error; and that the robustness of social transmission is thereby increased. We employed a simple model to demonstrate how culture that is produced through exact copying is fragile in an (even slightly) noisy world. When incorporating a certain degree of trial-and-error, however, cultures are more readily formed in a stochastic environment and are less vulnerable to rare ecological changes. We suggest that considering trial-and-error learning as a stabilizing component of social transmission may provide insights into cultural evolution in a realistic, variable, world.This article is part of the theme issue 'Bridging cultural gaps: interdisciplinary studies in human cultural evolution'.

Social Learning Strategies: Bridge-Building between Fields

While social learning is widespread, indiscriminate copying of others is rarely beneficial. Theory suggests that individuals should be selective in what, when, and whom they copy, by following 'social learning strategies' (SLSs). The SLS concept has stimulated extensive experimental work, integrated theory, and empirical findings, and created impetus to the social learning and cultural evolution fields. However, the SLS concept needs updating to accommodate recent findings that individuals switch between strategies flexibly, that multiple strategies are deployed simultaneously, and that there is no one-to-one correspondence between psychological heuristics deployed and resulting population-level patterns. The field would also benefit from the simultaneous study of mechanism and function. SLSs provide a useful vehicle for bridge-building between cognitive psychology, neuroscience, and evolutionary biology.

From Exploration to Instruction: Children Learn From Exploration and Tailor Their Demonstrations to Observers' Goals and Competence

This study investigated whether children learn from exploration and act as effective informants by providing informative demonstrations tailored to observers' goals and competence. Children (4.0-6.9 years, N = 98) explored a causally ambiguous toy to discover its causal structure and then demonstrated the toy to a naive observer. Children provided more costly and informative evidence when the observer wanted to learn about the toy than observe its effects (Experiment 1) and when the observer was ordinary than exceptionally intelligent (Experiment 2). Relative to the evidence they generated during exploration, children produced fewer, less costly actions when the observer wanted or needed less evidence. Children understand the difference between acting-to-learn and acting-to-inform; after learning from exploration, they consider others' goals and competence to provide "uninstructed instruction".

The impact of memory load and perceptual cues on puzzle learning by 24-month olds

Early childhood is characterized by memory capacity limitations and rapid perceptual and motor development [Rovee-Collier (1996). Infant Behavior & Development, 19, 385-400]. The present study examined 2-year olds' reproduction of a sliding action to complete an abstract fish puzzle under different levels of memory load and perceptual feature support. Experimental groups were compared to baseline controls to assess spontaneous rates of production of the target actions; baseline production was low across all experiments. Memory load was manipulated in Exp. 1 by adding pieces to the puzzle, increasing sequence length from 2 to 3 items, and to 3 items plus a distractor. Although memory load did not influence how toddlers learned to manipulate the puzzle pieces, it did influence toddlers' achievement of the goal-constructing the fish. Overall, girls were better at constructing the puzzle than boys. In Exp. 2, the perceptual features of the puzzle were altered by changing shape boundaries to create a two-piece horizontally cut puzzle (displaying bilateral symmetry), and by adding a semantically supportive context to the vertically cut puzzle (iconic). Toddlers were able to achieve the goal of building the fish equally well across the 2-item puzzle types (bilateral symmetry, vertical, iconic), but how they learned to manipulate the puzzle pieces varied as a function of the perceptual features. Here, as in Exp. 1, girls showed a different pattern of performance from the boys. This study demonstrates that changes in memory capacity and perceptual processing influence both goal-directed imitation learning and motoric performance.

Cumulative cultural learning: Development and diversity

The complexity and variability of human culture is unmatched by any other species. Humans live in culturally constructed niches filled with artifacts, skills, beliefs, and practices that have been inherited, accumulated, and modified over generations. A causal account of the complexity of human culture must explain its distinguishing characteristics: It is cumulative and highly variable within and across populations. I propose that the psychological adaptations supporting cumulative cultural transmission are universal but are sufficiently flexible to support the acquisition of highly variable behavioral repertoires. This paper describes variation in the transmission practices (teaching) and acquisition strategies (imitation) that support cumulative cultural learning in childhood. Examining flexibility and variation in caregiver socialization and children's learning extends our understanding of evolution in living systems by providing insight into the psychological foundations of cumulative cultural transmission-the cornerstone of human cultural diversity.

A Diverse and Flexible Teaching Toolkit Facilitates the Human Capacity for Cumulative Culture

Human culture is uniquely complex compared to other species. This complexity stems from the accumulation of culture over time through high- and low-fidelity transmission and innovation. One possible reason for why humans retain and create culture, is our ability to modulate teaching strategies in order to foster learning and innovation. We argue that teaching is more diverse, flexible, and complex in humans than in other species. This particular characteristic of human teaching rather than teaching itself is one of the reasons for human's incredible capacity for cumulative culture. That is, humans unlike other species can signal to learners whether the information they are teaching can or cannot be modified. As a result teaching in humans can be used to support high or low fidelity transmission, innovation, and ultimately, cumulative culture.

The Ontogeny of Cultural Learning

Developmental research has the potential to address some of the critical gaps in our scientific understanding of the role played by cultural learning in ontogenetic outcomes. The goal of this special section was to gather together leading examples of research on cultural learning across a variety of social contexts and caregiving settings. Although the field of developmental psychology continues to struggle with the persistent problem of oversampling U.S. and Western European populations, we argue that the articles in this special section add to the growing evidence that children everywhere draw on a repertoire of cultural learning strategies that optimize their acquisition of the specific practices, beliefs, and values of their communities. We also identify future directions and outline best practices for the conduct of research on cultural learning.

The boundaries of overimitation in preschool children: Effects of target and tool use on imitation of irrelevant actions

Overimitation is defined as the imitation of a series of actions, including causally irrelevant ones. Although previous studies have indicated that children's overimitation tends to be flexible, there is no research directly comparing overimitation occurrences due to types of irrelevant actions such as the target of irrelevant action or tool use. To identify the boundary of overimitation-that is, the point at which it occurs or not-Study 1 focused on the target of causally irrelevant tool-using actions. Specifically, the study examined the demonstration of irrelevant actions toward a main apparatus, a disconnected apparatus, or an actor's own body, followed by the demonstration of causally relevant actions, to 2-, 3-, and 5-year-old children (N=59). Results indicated that children overimitated actions toward the apparatuses more than they did the actions toward an actor's body. These results showed that overimitation was affected by the target, the apparatus, or the actor's own body. Study 2 investigated the effect of tool use toward the disconnected apparatus or an actor's body based on the findings in Study 1. Concretely, Study 2 added two actions without tool use (e.g., action toward an actor's own body without tool use and action toward an apparatus without tool use) to Study 1's actions for comparison. The results of this study showed that children overimitated the action toward the apparatus and the action with the tool more than the action toward an actor's own body and the action without the tool. Taken together, these findings suggest that two factors are involved in the occurrence of overimitation: the target of the action (i.e., the apparatus) and the use of a tool. The current findings provide suggestions for considering important aspects of overimitation that are worthy of more attention.

Is the tendency to conform influenced by the age of the majority?

The aim of the current study was to explore the influence that the age and the familiarity of a group majority has on copying fidelity in 4- to 6-year-old children. In Experiment 1, participants (N=120, M_age=68months) viewed five child models, all of whom were either younger than, the same age as, or older than themselves, open a puzzle box using an inefficient technique (four models) or an efficient technique (one model). In Experiment 2 (N=82, M_age=71months), the identical task was presented by groups of unfamiliar models. In both Experiments 1 and 2, a group of control participants saw an equal number of inefficient and efficient models. Results showed that the participants displayed conformity irrespective of the age, or the familiarity, of the individuals comprising the majority. However, the participants varied in their level of imitative fidelity depending on the identity of the group majority, with majorities that were either the same age as, or considerably older than, the participants eliciting the highest levels of over-imitation. In contrast, groups comprising individuals who were younger than the participants elicited a significantly lower level of over-imitation than that elicited by the same-aged and older majorities. We suggest that these findings demonstrate an interplay between conformist and model-based transmission biases.

Parents scaffold flexible imitation during early childhood

Children use imitation flexibly to acquire the instrumental skills and conventions of their social groups. This study (N=69 parent and 3- to 6-year-old child dyads) examined the impact of instrumental versus conventional language on (a) children's imitative flexibility in the context of parent-child interaction and (b) how parents scaffold children's imitation. Children in dyads presented with conventional language imitated with higher fidelity than children in dyads presented with instrumental language. Parents in dyads presented with conventional language also provided their children with more instruction to imitate and engaged in more encouragement, demonstration, and monitoring than parents in dyads presented with instrumental language. The relation between language cue and children's imitative fidelity was mediated by parent scaffolding behavior. The results provide evidence that caregivers support the development of flexible imitation during early childhood by adjusting their scaffolding according to the goal of the behavior.