Why do dogs ape if apes don't ape?

Range, Viranyi and Huber (2007) found that dogs exhibit imititative learning:

The transmission of cultural knowledge requires learners to identify what relevant information to retain and selectively imitate when observing others' skills. Young human infants — without relying on language or theory of mind — already show evidence of this ability. If, for example, in a communicative context, a model demonstrates a head action instead of a more efficient hand action, infants imitate the head action only if the demonstrator had no good reason to do so, suggesting that their imitation is a selective, interpretative process [1]. Early sensitivity to ostensive-communicative cues and to the efficiency of goal-directed actions is thought to be a crucial prerequisite for such relevance-guided selective imitation [2]. Although this competence is thought to be human specific [2], here we show an analog capacity in the dog. In our experiment, subjects watched a demonstrator dog pulling a rod with the paw instead of the preferred mouth action. In the first group, using the inefficient action was justified by the model's carrying of a ball in her mouth, whereas in the second group, no constraints could explain the demonstrator's choice. In the first trial after observation, dogs imitated the nonpreferred action only in the second group. Consequently, dogs, like children, demonstrated inferential selective imitation.

Last year I posted on "imitation" in infant macaques, and noted that the term has induced a lot of confusion:

Lately, the term has been limited to cases of learning where an individual is replicating the behaviors of another individual -- not only the end result, but also all the steps that lead to that end result. But the infant "imitation" quite clearly doesn't require the kind of conceptual learning that instances of "imitation" among older juveniles and adults seems to take.

The issue remains quite confusing, although there are clarifying statements on the issue to be found in the literature. A good discussion of the concept of "imitation" as applied to social learning in particular was provided by Byrne and Russon (1998), who interpreted learning of action sequences from the perspective of hierarchization:

To explain social learning without invoking the cognitively complex concept of imitation, many learning mechanisms have been proposed. Borrowing an idea used routinely in cognitive psychology, we argue that most of these alternatives can be subsumed under a single process, priming, in which input increases the activation of stored internal representations. Imitation itself has generally been seen as a "special faculty." This has diverted much research towards the all-or-none question of whether an animal can imitate, with disappointingly inconclusive results. In the great apes, however, voluntary, learned behaviour is organized hierarchically. This means that imitation can occur at various levels, of which we single out two clearly distinct ones: the "action level," a rather detailed and linear specification of sequential acts, and the "program level," a broader description of subroutine structure and the hierarchical layout of a behavioural "program." Program level imitation is a high-level, constructive mechanism, adapted for the efficient learning of complex skills and thus not evident in the simple manipulations used to test for imitation in the laboratory. As examples, we describe the food-preparation techniques of wild mountain gorillas and the imitative behaviour of orangutans undergoing "rehabilitation" to the wild. Representing and manipulating relations between objects seems to be one basic building block in their hierarchical programs. There is evidence that great apes suffer from a stricter capacity limit than humans in the hierarchical depth of planning. We re-interpret some chimpanzee behaviour previously described as "emulation" and suggest that all great apes may be able to imitate at the program level. Action level imitation is seldom observed in great ape skill learning, and may have a largely social role, even in humans.

I think it may be valuable to add yet another hierarchical level below the "action" level; perhaps a "fine motor" level of imitation. This would be the level that fine imitation of motions like a tennis swing occupy -- people learn these through intensive practice, including slow breaking-down of the motor sequence into separate steps that are put together into a single rapid motor performance. This kind of motor imitative learning may not be present in any other animals -- in fact, I doubt there is any evidence of this in prelinguistic hominids. Perhaps the process of analysis of action at this level requires language to negotiate the time scale of modeling and the process of segmentation.

Range et al. focus on a relatively simple version of imitative learning that involves some conceptual understanding of both the goals and the steps taken while performing an action:

This type of social learning from a conspecific model clearly exceeds purely motivational and perceptual forms of social influence, such as social facilitation and stimulus enhancement [22], as already demonstrated in dogs [23]. Italso deviates from simple forms of behavioral matching, such as response facilitation, i.e., the priming of an action already in the repertoire of the observer [24], because, even though the pretest showed that all animals had paw use in their repertoire, observers of both experimental groups started out by using their mouth instead of the demonstrated paw action to manipulate the rod. The quick and radical shift in the mouth-free group to adopt the paw action, for which there is no tendency in the control group, indicates an imitative form of social learning according to Thorpe [25], e.g., "as a significant elevation in the frequency of an observed action over the normal probability of its occurrence" [26] (reviewed in 27, 28, 29, 30 and 31, but see also 32 and 33).

The experiment involved an apparatus that required the dogs to pull down on a rod to obtain a food reward. Naïve dogs tended to use their mouths on the apparatus. The experimenters set up some dogs so that they could see a trained dog pull down the rod with her paw instead of her mouth. And, this is important, the dogs were primed with communicative cues from the model dog and the humans. Then, these groups were allowed to try the apparatus; upon which a high fraction of the experimental groups started using their paws to pull down the rod.

So the dogs are imitating in at least a chimpanzee-like or toddler-like way. And we bred them to do it! That may indicate that the basis for this ability is relatively shallow, in that it can be elicited with concerted selection, and without a long process of specialized evolution.

References:

Range F, Viranyi Z, Huber L. 2007. Selective imitation in domestic dogs. Curr Biol (in press) doi:10.1016/j.cub.2007.04.026

Byrne RW, Russon AE. 1998. Learning by imitation: a hierarchical approach. Behav Brain Sci 21:667-684.

Horner V, Whiten A. 2005. Causal knowledge and imitation/emulation switching in chimpanzees (Pan troglodytes) and children (Homo sapiens), Anim Cogn 8:164-181

Whiten A, Horner V, Litchfield CA, Marschall-Pescini S. 2004. How do apes ape? Learn Behav 32:36-52.

Voelkl B, Huber L. 2000. True imitation in marmosets. Anim Behav 60:195-202.