Imitation by combination: preschool age children evidence summative imitation in a novel problem-solving task

People overlook subtractive changes differently depending on age, culture, and task

Previous work has explored transformative strategies that adds or removes components to change an original structure or state, and showed that adults tend to search for additive solutions far more often than subtractive ones. In the current study, we replicated a Lego building task and a grid-based symmetry task from a previous study, and also introduced a novel digital puzzle task. We investigated limitations in the previous study as well as extended the investigation of the subtraction neglect in a sample of children and across two cultures. Results partially confirm previous results, and extends the literature by showing that 9-10 year old children were more likely to ignore subtractive transformations than adults. However, we found both task-based and cultural variations in strategy use in adults from Sweden and the USA. We conclude that a subtraction neglect involves complex cognitive processes that are dependent on the task, culture, and age.

Generative cultural learning in children and adults: the role of compositionality and generativity in cultural evolution

Are human cultures distinctively cumulative because they are uniquely compositional? We addressed this question using a summative learning paradigm where participants saw different models build different tower elements, consisting of discrete actions and objects: stacking cubes (tower base) and linking squares (tower apex). These elements could be combined to form a tower that was optimal in terms of height and structural soundness. In addition to measuring copying fidelity, we explored whether children and adults (i) extended the knowledge demonstrated to additional tower elements and (ii) productively combined them. Results showed that children and adults copied observed demonstrations and applied them to novel exemplars. However, only adults in the imitation condition combined the two newly derived base and apex, relative to adults in a control group. Nonetheless, there were remarkable similarities between children's and adults' performance across measures. Composite measures capturing errors and overall generativity in children's and adults' performance produced few population by condition interactions. Results suggest that early in development, humans possess a suite of cognitive skills-compositionality and generativity-that transforms phylogenetically widespread social learning competencies into something that may be unique to our species, cultural learning; allowing human cultures to evolve towards greater complexity.

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.

Optimizing imitation: Examining cognitive factors leading to imitation, overimitation, and goal emulation in preschoolers

Humans imitate patently irrelevant actions known as overimitation, and rather than decreasing with age, overimitation increases with age. Whereas most overimitation research has focused on social factors associated with overimitation, comparatively little is known about the cognitive- and task-specific features that influence overimitation. Specifically, developmental contrasts between imitation and overimitation are confounded by the addition of irrelevant actions to causally necessary actions, increasing sequence length, cognitive load, and processing costs-variables known to be age dependent. We constructed a novel puzzle box task such that a four-step imitation, four-step overimitation, and two-step efficient sequence could be demonstrated using the same apparatus on video. In Experiments 1 and 2, 2.5- to 5-year-olds randomly assigned to imitation and overimitation groups performed significantly more target actions than baseline control groups. Rates of imitation and overimitation increased as a function of age, with older preschoolers outperforming younger preschoolers in both conditions. In Experiment 3, preschoolers were shown a video of an efficient two-step demonstration prior to testing. After they responded, they were shown a four-step overimitation video and were tested on the same puzzle box. Children imitated the efficient demonstration, but after watching the overimitation video, they also overimitated the irrelevant actions. Once again, older children overimitated more than younger children. Together, results show that preschoolers are faithful, flexible, and persistent overimitators. The fidelity and flexibility of overimitation are constrained not only by social factors but also by basic cognitive processes that vary across age groups. As these constraints diminish, overimitation and flexible (optimal) imitation increases.