Thursday, December 13, 2007

Well, Mimes Still Suck

So in my last post I wrote about the importance of vocal imitation for the evolution of language. According to Hauser et al. (2002), it is one of the most important species-specific, but not language-specific components that make up the faculty of language in the broad sense (FLB), as opposed to the faculty of language in the narrow sense, (FLN), which they equate with the
"core computational mechanisms of recursion as they appear in narrow syntax and the mappings to the interfaces [of the conceptual-intentional system (e.g. vocal imitation, sound-pattern discrimination, language perception and production, etc.) and the sensory-motor system(e.g. Theory of Mind, nonlinguistic conceptual representations, voluntary control over signal production, etc.) - and whatever you think should be seen as a part of it, Hauser et al. don't care]" (Hauser et al. 2002: 1573)
Whatever that is supposed to mean.
Hauser et al. also list
"Imitation as a rational, intentional system" (Hauser et al. 2002: 1573)
as a component of the conceptual-intentional system, and cite
"Comparative studies of chimpanzees and human infants suggesting that only the latter read intentionality into action, and thus extract unobserved rational intent" (Hauser et al. 2002: 1573).This remark touches upon the messy theory of mind debate in the cognitive sciences and elsewhere. Hauser et al. seem to assume that there is an intrinsic link between some forms of imitation and the attribution of intent to the other. They report that chimpanzees seem to have only minimal visual-imitative capacities, and that there is almost no evidence for them in monkeys (Hauser et al. 2002: 1575). According to Hauser et al. this seems to confirm that non-human apes and monkeys are not able to attribute intentions to others.

However, it seems that chimpanzees at reading others behavioral programs, and predicting their future actions without needing to attribute mental states to con-specifics. (Byrne and Russon 1998) In general, just as language is not a monolithic whole, imitation probably is also a cognitive capacity consisting of various component parts. Byrne and Russon (1998) propose that Imitation is in fact a task that is hierarchically divided in separate forms of imitation, that is
  1. Imitation as Goal Imitation (i.e. achieve the same result, e.g. eating a fruit, possibly in a roughly similar as someone before you).
  2. Imitation at the Program Level (i.e. simulate the actions at a broad behavioral level, representing the organizational structure of an action, without imitating it in detail)
  3. Impersonation, or "True Imitation" (i.e. simulate the other's motoric actions in detail)
According to Byrne and Russon (1998), all great apes are able to imitate behavior at the second level, and the use of "action level" imitation is primarily restricted to humans (although they speculate that in non-human great apes, this may be more a matter of motivation than ability), but only plays a minor role, because even such complex skills as the learning of language (e.g. sound production) are achieved on the program level because they do not actually imitate the physical sounds but the organizational structure of the sound system. However, they don't really come up with a good explanation why action level imitation exists in humans at all, and even doubt that it plays an important or even frequent role at all.

As Tomasello (1998) rightly criticizes, this largely downplays the role of shared human cultural and cognitive artifacts and the creative use to which they can put in order to facilitate new functional dimensions and therefore progress, and fails to explain what it is that is special about humans, and why cultural transmission in humans is so much more powerful than in other apes.
They also greatly underestimate the importance of the arbitrary, conventionalized nature of the (Saussurean) linguistic sign, which is crucial for the establishment of a successfully communicating group of agents (Which is also why my blog's title alludes to this principle. I'll come back to this in a subsequent post)
I think it is interesting to contrast Byrne and Russon's model with evidence of so-called conformity bias in chimpanzees.
Whiten et al. (2005) taught two distinct tool-use techniques to two high-ranking female chimpanzees, and then brought them back to their groups. 30 of 32 chimpanzees adopted the female chimpanzees technique. Some chimpanzee at first discovered different means of tool-use, which could be explained in terms of broad organizational imitation, but later also adopted the predominating technique of their group, even if they were able to use both techniques and both very equally successful. If chimpanzees would act only at a broad behavioral level, then this effect surely wouldn’t have occurred. Thus, there is evidence that even in chimpanzees there is the convergence of complex behavioral patterns (we could even call them ‘memes’ if we felt like it) to a cultural norm. Thus, such tendencies must have a deeper evolutionary heritage than assumed before.
Furthermore, Byrne and Russon write that
"We suspect, however, that action level imitation is less common in children than it seems, and that, often, children’s “imitation” may reflect response facilitation." (Byrne and Russon 1998: 683)"
This, however, is clearly refuted by experiments done by Lyons et al. (2007), which I will describe in my next post. (In the meantime, however, you should rather go read Carl Zimmer's heartening and much more enjoyable blog post and article in the New York Times about the fate of his daughter in comparative tests between human children and chimpanzees. )
Without question, Byrne and Russon's model is not able to give a complete theory of imitation, which is why I will look at some other approaches in my next post


Byrne, Richard W and Anne E. Russon. 1998. “Learning by Imitation: a Hierarchical Approach.” Behavioral and Brain Sciences 21.5: 667-684

Hauser, Marc D., Noam Chomsky and W. Tecumseh Fitch 2002. “The Faculty of Language: What Is It, Who Has It, and How Did It Evolve?” Science 298: 1569-1579.

Lyons, Derek E.. Andrew G. Young, and Frank C. Keil. 2007. “The Hidden Structure of Overimitation” PNAS 105.50: 19751–19756.

Tomasello, Michael. 1998. “Emulation learning and cultural learning.” Behavioral and Brain Sciences 21.5: 703-704.

Whiten, Andrew, Victoria Horner & Frans B. M. de Waal. 2005. “Conformity to Cultural Norms of Tool Use in Chimpanzees.” Nature 437: 737-740.

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