Abstract: Imitation can be defined as the copying of behavior. To a biologist, interest in imitation is focused on its adaptive value for the survival of the organism, but to a psychologist, the mechanisms responsible for imitation are the most interesting. For psychologists, the most important cases of imitation are those that involve demonstrated behavior that the imitator cannot see when it performs the behavior (e.g., scratching one's head). Such examples of imitation are sometimes referred to as opaque imitation because they are difficult to account for without positing cognitive mechanisms, such as perspective taking, that most animals have not been acknowledged to have. The present review first identifies various forms of social influence and social learning that do not qualify as opaque imitation, including species-typical mechanisms (e.g., mimicry and contagion), motivational mechanisms (e.g., social facilitation, incentive motivation, transfer of fear), attentional mechanisms (e.g., local enhancement, stimulus enhancement), imprinting, following, observational conditioning, and learning how the environment works (affordance learning). It then presents evidence for different forms of opaque imitation in animals, and identifies characteristics of human imitation that have been proposed to distinguish it from animal imitation. Finally, it examines the role played in opaque imitation by demonstrator reinforcement and observer motivation. Although accounts of imitation have been proposed that vary in their level of analysis from neural to cognitive, at present no theory of imitation appears to be adequate to account for the varied results that have been found.

Abstract: In the wake of telling critiques of the foundations on which earlier conclusions were based, the last 15 years have witnessed a renaissance in the study of social learning in apes. As a result, we are able to review 31 experimental studies from this period in which social learning in chimpanzees, gorillas, and orangutans has been investigated. The principal question framed at the beginning of this era, Do apes ape? has been answered in the affirmative, at least in certain conditions. The more interesting question now is, thus, How do apes ape? Answering this question has engendered richer taxonomies of the range of social-learning processes at work and new methodologies to uncover them. Together, these studies suggest that apes ape by employing a portfolio of alternative social-learning processes in flexibly adaptive ways, in conjunction with nonsocial learning. We conclude by sketching the kind of decision tree that appears to underlie the deployment of these alternatives.

Abstract: A. Whiten, D. M. Custance, J.-C. Gomez, P. Teixidor, and K. A. Bard (1996) tested chimpanzees' (Pan troglodytes) and human children's (Homo sapiens) skills at imitation with a 2-action test on an “artificial fruit.” Chimpanzees imitated to a restricted degree; children were more thoroughly imitative. Such results prompted some to assert that the difference in imitation indicates a difference in the subjects' understanding of the intentions of the demonstrator (M. Tomasello, 1996). In this experiment, 37 adult human subjects were tested with the artificial fruit. Far from being perfect imitators, the adults were less imitative than the children. These results cast doubt on the inference from imitative performance to an ability to understand others' intentions. The results also demonstrate how any test of imitation requires a control group and attention to the level of behavioral analysis.

Abstract: We review socially biased learning about food and problem solving in monkeys, relying especially on studies with tufted capuchin monkeys (Cebus apella) and callitrichid monkeys. Capuchin monkeys most effectively learn to solve a new problem when they can act jointly with an experienced partner in a socially tolerant setting and when the problem can be solved by direct action on an object or substrate, but they do not learn by imitation. Capuchin monkeys are motivated to eat foods, whether familiar or novel, when they are with others that are eating, regardless of what the others are eating. Thus, social bias in learning about foods is indirect and mediated by facilitation of feeding. In most respects, social biases in learning are similar in capuchins and callitrichids, except that callitrichids provide more specific behavioral cues to others about the availability and palatability of foods. Callitrichids generally are more tolerant toward group members and coordinate their activity in space and time more closely than capuchins do. These characteristics support stronger social biases in learning in callitrichids than in capuchins in some situations. On the other hand, callitrichids' more limited range of manipulative behaviors, greater neophobia, and greater sensitivity to the risk of predation restricts what these monkeys learn in comparison with capuchins. We suggest that socially biased learning is always the collective outcome of interacting physical, social, and individual factors, and that differences across populations and species in social bias in learning reflect variations in all these dimensions. Progress in understanding socially biased learning in nonhuman species will be aided by the development of appropriately detailed models of the richly interconnected processes affecting learning.

Abstract: We present evidence that a dog (Philip, a 4-year-old tervueren) was able to use different human actions as samples against which to match his own behaviour. First, Philip was trained to repeat nine human-demonstrated actions on command ('Do it!'). When his performance was markedly over chance in response to demonstration by one person, testing with untrained action sequences and other demonstrators showed some ability to generalise his understanding of copying. In a second study, we presented Philip with a sequence of human actions, again using the 'Do as I do' paradigm. All demonstrated actions had basically the same structure: the owner picked up a bottle from one of six places; transferred it to one of the five other places and then commanded the dog ('Do it!'). We found that Philip duplicated the entire sequence of moving a specific object from one particular place to another more often than expected by chance. Although results point to significant limitations in his imitative abilities, it seems that the dog could have recognized the action sequence, on the basis of observation alone, in terms of the initial state, the means, and the goal. This suggests that dogs might acquire abilities by observation that enhance their success in complex socio-behavioural situations.