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A newborn rhesus macaque imitates tongue protrusion.

Imitation is an advanced behavior whereby an individual observes and replicates another's. The word can be applied in many contexts, ranging from animal training to international politics.

[edit] Anthropology and social sciences

In anthropology, diffusion theories explain why cultures imitate the ideas or practices of other cultures. Some theories hold that all cultures imitate ideas from one or a few original cultures, the Adam of the Bible, or several cultures whose influence overlaps geographically. Evolutionary diffusion theory holds that cultures influence one another, but that similar ideas can be developed in isolation.

Scholars^[1] as well as popular authors^[2] have argued that the role of imitation in humans is unique among animals. Psychologist Kenneth Kaye showed that infants' ability to match the sounds or gestures of an adult depends on an interactive process of turn-taking over many successive trials, in which adults' instinctive behavior plays as great a role as that of the infant.^[3] These writers assume that evolution would have selected imitative abilities as fit because those who were good at it had a wider arsenal of learned behavior at their disposal, including tool-making and language.

In the mid-20th century, social scientists began to study how and why people imitate ideas. Everett Rogers pioneered innovation diffusion studies, identifying factors in adoption and profiles of adopters of ideas.

Imitation is a replication of a meme.

[edit] Neuroscience

That we are capable of imitating movements, actions, skills, behaviors, gestures, pantomimes, mimics, vocalisations, sounds, speech etc. and that we have particular 'imitation systems' in the brain is old neurological knowledge dating back to Hugo (Karl) Liepmann 1863-1925 (see Wikipedia). Liepmann's model 1908 "Das hierarchische Modell der Handlungsplanung" (the hierarchical model of action planning) is still valid. On studying the cerebral localization of function, Liepmann postulated that planned or commanded actions were prepared in the parietal lobe of the brain's dominant hemisphere, and also frontally. His most important pioneering work is when extensively studying patients with lesions in these brain areas, he discovered that the patients lost (among other things) the ability to imitate. He was the one who coined the term 'apraxia' and differentiated between ideational and ideomotor apraxia. In this basic and wider frame of classical neurological knowledge the discovery of the mirror neurons has to be seen, which was made in monkeys but of course holds for man as well.

fMRI human brain studies revealed a network of regions in the inferior frontal cortex and inferior parietal cortex which are typically activated during imitation tasks.^[4] It has been suggested that these regions contain mirror neurons similar to the mirror neurons recorded in the macaque monkey.^[5] However, it is not clear if macaques spontaneously imitate each other in the wild.

Neurologist V.S. Ramachandran argues that the evolution of mirror neurons were important in the human acquisition of complex skills such as language and believes the discovery of mirror neurons to be a most important advance in neuroscience.^[6] However, little evidence directly supports the theory that mirror neuron activity is involved in

functions such as empathy or learning by imitation.^[7]

Evidence is accumulating that bottlenose dolphins employ imitation to learn hunting and other skills from other dolphins.^[8][9]

[edit] Animal behavior

Scientists debate whether animals can truly imitate novel actions or whether imitation is uniquely human.^[10] The current controversy is partly definitional. Thorndike uses 'learning to do an act from seeing it done'.^[11] It has two major shortcomings: first, by using 'seeing' it restricts imitation to the visual domain and excludes e.g. vocal imitation and, second, it would also include mechanisms such as priming, contagious behaviour and social facilitation ^[12], which most scientist distinguish as separate forms of observational learning. Thorpe suggested defining imitation as 'the copying of a novel or otherwise improbable act or utterance, or some act for which there is clearly no instinctive tendency'.^[13] This definition is favored by many scholars, though questions have been raised how strictly the term 'novel' has to be interpreted and how exactly a performed act has to match the demonstration to count as a copy.

In 1952 Hayes & Hayes ^[14] used the 'Do-as-I-do' procedure to demonstrate the imitative abilities of their trained chimpanzee 'Viki'. Their study was repeatedly criticized for its subjective interpretations of their subjects' responses. Replications of this study ^[15] found much lower matching degrees between subjects and models. However, imitation research focusing on the copying fidelity got new momentum from a study by Voelkl and Huber.^[16] They analyzed the motion trajectories of both model and observer monkeys and found a high matching degree in their movement patterns.

Paralleling these studies, comparative psychologists provided tools or apparatuses that could be handled in different ways. Heyes ^[17][18] and co-workers reported evidence for imitation in rats that pushed a lever in the same direction as their models, though later on they withdrew their claims due to methodological problems in their original setup.^[19] By trying to design a testing paradigm that is less arbitrary than pushing a lever to the left or to the right, Custance and co-workers ^[20] introduced the 'artificial fruit' paradigm, where a small object could be opened in different ways to retrieve food placed inside'not unlike a hard-shelled fruit. Using this paradigm, scientists reported evidence for imitation in monkeys.^[21][22] and apes ^[23][24][25] There remains a problem with such tool (or apparatus) use studies: what animals might learn in such studies need not be the actual behaviour patterns (i.e. the actions) that were observed. Instead they might learn about some effects in the environment (i.e. how the tool moves, or how the apparatus works.^[26]) This type of observational learning, which focuses on results, not actions, has been dubbed emulation (see Emulation (observational learning)).

[edit] See also

• Cognitive imitation
• Mimicry
• Modelling (psychology)
• Secondhand obesity
• Associative Sequence Learning

[edit] References

• Liepmann, H. (1900). Das Krankheitsbild der Apraxie (motorische Asymbolie). S. Karger Publ., Berlin.
• Liepmann, H. (1905). Über die Störungen des Handelns bei Gehirnkranken. S. Karger Verlag, Berlin.
• Liepmann, H. (1908). Drei Aufsätze aus dem Apraxiegebiet. S. Karger Publ., Berlin.
• Liepmann, H. (1920). Apraxie. Ergebn ges Med 1: 516-543.

[edit] Further reading

• Zentall, T.R. (2006). Imitation: Definitions, evidence, and mechanisms. Animal Cognition, 9, 335-353. Full text