We investigated children's understanding of directed motion events using an Imitation Choice paradigm. Thirty-four children (mean age 33 months) watched a model act out an event containing a manner of motion (hopping or sliding), a motion path (up or down a ramp), and a goal (in or on a bowl). On the child's apparatus, the locations of the goal objects were different from the model so that the child had to choose whether to imitate the path or the goal of the model's event. Children's choice of which component to imitate therefore reflects how they prioritize these event components. Most children showed no bias to imitate the goal of the event, and instead preferred to imitate the model's path at the expense of the model's goal. However, children who spontaneously played with the goal objects during a free-play session showed a diminished path preference, choosing to imitate path and goal components equally often. We suggest that children's prioritization of information within an event depends on how that information is structured within the event itself. Keywordsimitation; event representation; toddler; directed-motion event; goals Imitation is an important tool of social learning that allows humans to replay an event that just occurred in the same way they witnessed it. It is also an important window onto children's representations: successful imitation requires a child to adequately represent the event in question. Moreover, for revealing how they represent and organize information, children's failures are as important as their successes. For example, a child who successfully imitates a model's ultimate goal while failing to imitate the model's process steps (a case of "emulation") most likely has a representation of the event that privileges or prioritizes the goal of the event. And indeed, the dominant finding in the literature is that infants and toddlers are goal-biased in their representations. However, generalizing from children's failures and omissions is not without difficulty. A child who fails too often may simply not have the ability to do the task; a child who fails too rarely may not make representative mistakes. In addition, there is the problem of interpreting null results: children might fail to do something for many reasons. Obviously, systematic patterns of success and failure can be quite meaningful -and many such patterns will be discussed below. However, the method adopted in this paper opts for a different solution, by forcing children to make choices.

Three capuchin monkeys (Cebus apella) were tested on a 2-choice discrimination task designed to examine their knowledge of support, modeled after Hauser, Kralik, and Botto-Mahan's (1999) experiments with tamarins. This task involved a choice between 2 pieces of cloth, including 1 with a food reward placed on its surface, and a second cloth with the food reward next to its surface. After reliably solving the basic problem, the capuchins were tested with various alternations of the original food reward and cloth. The capuchins were able to solve the initial task quickly, and generalize their knowledge to additional functional and nonfunctional variations of the problem. In comparison to the tamarins previously tested on this problem (Hauser et al., 1999), the capuchins were able to reach criterion faster during the training and food size conditions and showed a greater ability to inhibit reaching toward larger food rewards that were unavailable.

Studies of causal understanding of tool relationships in captive chimpanzees have yielded disparate findings, particularly those reported by Povinelli & colleagues (2000) for tool tasks by laboratory chimpanzees. The present set of experiments tested nine enculturated chimpanzees on three versions of a support task, as described by Povinelli (2000), during which food rewards were presented in different experimental configurations. In Experiment 1, stimulus pairs included a choice between a cloth with a reward on the upper right corner or with a second reward off the cloth, adjacent to a corner, with the second pair comprised of a cloth with food on the upper right corner, and a second cloth with the reward on the substrate, partially covered. All subjects were successful with both test conditions in Experiment 1. In a second study, the experimental choices included one of two possible correct options, paired with one of three incorrect options, with the three incorrect choices all involving varying degrees of perceptual containment. All nine chimpanzees scored significantly above chance across all six conditions. In Experiment 3, four unique conditions were presented, combining one of two possible correct choices with one of two incorrect choices. Six of the subjects scored significantly above chance across the four conditions, and group performance on individual conditions was also significant. Superior performance was demonstrated by female subjects in Experiment 3, similar to sex differences in tool use previously reported for wild chimpanzees and some tool tasks in captive chimpanzees. The present results for Experiments 2 & 3 were significantly differed from those reported by Povinelli et al. (2000) for laboratory-born, peer-reared chimpanzees. One contribution towards the dramatic differences between the two study populations may be the significant rearing and housing differences of the chimpanzee groups. One explanation is that under conditions of enculturation, rich social interactions with humans and conspecifics, as well as active exploration of artifacts, materials, and other aspects of their physical environment had a significant impact on the animals' ability to recognize the support relationships among the stimulus choices. Overall, the present findings provide strong support for the hypothesis that our chimpanzee subjects based their responses on an understanding of functional support which represented one facet of their folk physics repertoire [Current Zoology 57 (4): 429-440, 2011]. Keywords Chimpanzees, Comparative cognition, Tool use, CausalityTool use by wild chimpanzees is a ubiquitous feature of daily life in many chimpanzee communities across equatorial Africa, and is represented by a range of cultures within these populations that regularly use tools that can be specific to the community (Boesch and Boesch, 1990;Boesch-Achermann and Boesch, 1993;Goodall, 1986;McGrew, 1992;Sakura and Matsuzawa, 1991;Whiten et al., 1999). Since the initial discoveries by Goodall (1964), each year,...

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