Social learning and imitation in human and nonhuman primates

Most people assume that monkeys and apes can imitate, but recently, several researchers have suggested there is little convincing evidence of imitation in any nonhuman species. The purpose of the present thesis is to compare the imitative abilities of human and non-human primates. Some of the most convincing evidence for imitation comes from anecdotal reports of imitative behaviour in great apes. A survey of the literature was performed and a database of imitative episodes in chimpanzees, gorillas and orangutans was compiled (using a similar approach to Whiten & Byrne's 1988a tactical deception database). Each report was subjected to a strict evaluation, and it was deemed that 23 reports from chimpanzees, 3 from gorillas and 4 from orangutans provided relatively convincing evidence of imitation. An experiment was conducted to test if chimpanzees can imitate as the anecdotal data suggests. Two chimpanzees were taught to reproduce 15 arbitrary gestures on the command "Do this". Next they were presented with 48 novel items. They imitated 13 and 20 novel gestures respectively. Using a rigorous coding system, two independent observers correctly identified a significant number of the chimpanzees' imitations (P< 0.0001). These results show that chimpanzees are capable of the complex intermodal visual-motor co-ordination and control necessary for imitation. The second experimental chapter explores whether monkeys, apes, and/or humans imitate in the context of a functional task. Six capuchin monkeys (Cebus apella), eight chimpanzees (Pan troglodytes) and 24 children were presented with an analogue of a natural food processing task. The subjects were divided into two groups and each saw a different method for opening an artificial fruit. The children showed quite extensive imitation; the capuchin monkeys showed little to none; while the chimpanzees showed marginal imitative abilities. This constitutes the first experimental evidence of functional object imitation in a nonhuman specie

A counterbalanced version of Ainsworth's Strange Situation Procedure reveals secure-base effects in dog-human relationships

It has been proposed that the dog–human relationship constitutes an infantile-like attachment. However, previous empirical support based on Ainsworth's Strange Situation test has proved inconclusive due to order effects inherent in the original procedure. In particular, these order effects compromise the ability to establish an essential facet of attachment: whether or not owners function as a secure base for their pet dogs. Order effects were counteracted in the present study by including a second condition in which the order of owner and stranger presence was counterbalanced. Hence, 38 adult dog-owner pairs were randomly placed in two conditions, both comprised of six 3-min episodes. In condition A, dogs entered an unfamiliar room with their owner; a stranger entered; the owner left the dog with the stranger; the dog was left alone in the room; the owner returned; and finally the dog was left with the stranger again. In condition B, the order in which owner and stranger were present was reversed. Secure-base effects were indicated in that the dogs explored, remained passive, played with the stranger and engaged in individual play more when in the presence of their owner than when left with the stranger or alone. Therefore, the dogs’ behaviour provides evidence consistent with the hypothesis that the dog–human bond constitutes an attachment. The possible role of attachment in canine separation anxiety is briefly discussed

Social learning of an artificial fruit task in capuchin monkeys (Cebus apella).

Social learning in 11 human-raised capuchin monkeys (Cebus apella) was investigated using an artificial fruit that was designed as an analogue of natural foraging problems faced by primates. Each subject observed a human model open each of 3 principal components on the fruit in 1 of 2 alternative ways ("morphs"). The capuchin monkeys reproduced, to differing extents, the alternative techniques used for opening 1 component of the task (poking vs. pulling while twisting out a pair of smooth plastic bolts) but not the other 2. From the subjects' actions on the bolt latch, independent coders could recognize which morph they had witnessed, and they observed a degree of matching to the demonstrator's act consistent with simple imitation or object movement reenactment (A learns from watching B how an object, or parts of an object, move). Thus, these capuchins were capable of more complex social learning than has been recently ascribed to monkeys

Social learning and primate reintroduction

Research on social learning may be of use in the conservation of primates, especially great apes, through (a) promoting their public image, (b) identifying specific adaptations, and (c) devising reintroduction training programs. We surveyed all the instigated social learning studies in primates published since 1950 in order to assess their usefulness to devise reintroduction training programs. We identified 99 publications containing 130 data sets from 27 species of primates. Great apes produced significantly more positive social learning effects than either cercopithecines or cebids. There was also an enhanced social learning effect when skilled demonstrators were used. Our survey indicates that the scientific understanding of many aspects of primate social learning relevant to conservation, including its function, learning spatial route plotting, food and sleeping site location, predator avoidance and detection, and the effect of model and tutee status, would benefit from greater research. Future instigated studies on primate social learning would be most informative for reintroduction if they included ecologically valid tasks presented to greater than or equal to2 similarly composed social groups, one of which functioned as a control, i.e., without being exposed to a model.</p

Can young chimpanzees (Pan troglodytes) imitate arbitrary actions? Hayes & Hayes (1952) revisited

Contrary to recent scepticism, systematic use of an experimental approach suggested by Hayes & Hayes (1952) shows that chimpanzees can imitate novel actions. Two chimpanzees imitated 13 and 17 novel arbitrary gestures, respectively. They were first taught to reproduce 15 gestures on the command, "Do this!", and then presented with 48 novel items. Using a rigourous coding system, two independent observers correctly identified a significant number of the chimpanzees' imitations (p < 0.0001). We conclude that after a period of tuition chimpanzees can go on to imitate arbitrary actions, providing evidence of a basic cognitive capacity for perspective-taking and cross-modal matching

Imitative learning of artificial fruit processing in children (Homo sapiens) and chimpanzees (Pan troglodytes).

Observational learning in chimpanzees and young children was investigated using an artificial fruit designed as an analog of natural foraging problems faced by primates. Each of 3 principal components could be removed in 2 alternative ways, demonstration of only one of which was watched by each subject. This permitted subsequent imitation by subjects to be distinguished from stimulus enhancement. Children aged 2–4 years evidenced imitation for 2 components, but also achieved demonstrated outcomes through their own techniques. Chimpanzees relied even more on their own techniques, but they did imitate elements of 1 component of the task. To our knowledge, this is the first experimental evidence of chimpanzee imitation in a functional task designed to simulate foraging behavior hypothesized to be transmitted culturally in the wild