Our rich and diverse cultural landscape has arisen not only from our ability to innovate but also because we can copy others and build upon the knowledge of previous generations. This unique human ability to so diversely imitate has been coined Homo imitans. However, a debate has taken place whether our capacity to copy all kinds of behavior ranging from complex tea ceremonies, to mimicking body movements are due to a sophisticated imitation capacity, or rather reflects a more general learning mechanism (Heyes 2016). This entry explores the distinction between immediate and deferred imitation to discuss the notion of a specialized imitation system versus a more general action-perception matching system from a developmental, neuroscientific, as well as a comparative perspective.
In the literature, a distinction has been made between immediate, or also-called on-line imitation where the imitator repeats the model at the same time, and deferred imitation, where the action repetition between model and imitator is delayed. Cognitive theorists highlight deferred imitation as a way of investigating long-term memory in preverbal infants (Meltzoff 1988). Deferred imitation is relevant to theorists because the infant or child will not always be able to reproduce each adult action as soon as it is demonstrated; thus, for imitation to fulfill its socio-cultural utility, the infant or child must be capable of initiating imitation in the absence of the model. Finally, Piagetians focus on deferred imitation as a developmental milestone that first emerges at about 18–24 months, as part of a general emergence of the “symbolic function” enabling representational behavior beyond sensorimotor control (Piaget 1952). For both immediate as well as deferred imitation, we first have to define what counts as imitation. Whereas some theories stress the fact that the movements of the model and the imitator have to share the same topographical characteristics to be labeled as imitation (Brass and Heyes 2005), other theories have stressed that imitation can also be seen as a more goal-directed copying behavior, where imitators copy the goal of an action rather than the movement themselves (Bekkering et al. 2000; Wohlschläger et al. 2003). Below, I will outline how this distinction might be less clear-cut than what has been argued before.
Imitation has a long tradition in developmental psychology and was used as a mean to get insights in cognitive human development. Guided by findings from Meltzoff and colleagues, it was stressed that topographical imitation is an inborn mechanism (Meltzoff and Moore 1977), newborns can imitate facial and manual actions by means of an active intermodal matching systems in which proprioceptive information is matched in the observer from perceptual input to motor output. The notion of an inborn imitation mechanism was supported by neurological findings of so-called mirror neurons, i.e., neurons that fire both when an animal acts and when the animal observes the same action performed by another (Rizzolatti and Craighero 2004). As referred earlier, findings of Piaget indicate that deferred imitation can only take place around the second year of life, when children start to cook meals or are driving toy cars in similar manners as their parents do with their adult-size toys (Piaget 1952). Unfortunately, this division in development does not seem to hold. There is abundant evidence that newborns do not imitate in a topographical manner (Ray and Heyes 2011), and it has also been shown that we have limited capacities to imitate elementally novel actions over the whole lifespan (Heyes 2016). Also, follow-up studies of the mirror-neuron mechanisms showed that firing was not dependent on topographical characteristics but rather on goal-directed characteristics (Umiltà et al. 2001). Many cells fire in an effector-independent as well as a perceptually multimodal manner (Kohler 2002). In line with the notion that imitation serves the initiation of already known behavior, rather than learning novel actions, mirror neurons also typically respond to actions that are in the primate’s motor repertoire, as is the case when they have learned to use pliers to grasp a peanut (Umilta et al. 2008), although suggestions that mirror neurons can also derive from solely visual observations are also reported (Ferrari et al. 2005). To summarize, there is little evidence supporting the claim that an inborn mechanism serves imitation in newborns. Rather, on the basis of sensorimotor experiences, human infants learn to imitate immediately, or in a deferred manner. Clearly, the ability to imitate more complex actions depends on general cognitive capacities like working memory, and deferred imitation is used clinically to test amnesic patients for their loss of declarative memory (McDonough et al. 1995). The latter can be taken as evidence that imitation is not based on a simple stimulus-response (S-R) association between model and imitator akin to topographical imitation accounts. However, contemporary associative learning theory will still stress that an imitative action can be produced in the absence of the stimulus on the basis of what observers have observed earlier (Heyes 2016). As a consequence, a certain motivational urge to produce an action when observing an acting model can be based on the expected consequences of performing a specific action rather than reproducing the specific action observed. Such an outcome-based view on imitation includes the observation that when children are confronted with an extraordinary action, i.e., somebody touches his ear with her contralateral hand, this might evoke a different action, activating the ipsilateral hand, to touch the ear (Bekkering et al. 2000).
There is little doubt that humans are more skilled and prolific imitators than other animals, but the question is whether this is related to a special, inborn “intermodal matching” mechanism that integrates representations of others with representations of the self, or if it reflects more general cognitive capacities is still open. There is ample evidence that other animals have some capacity for imitation and also that this is experience dependent. Chimpanzees, for instance, have been found that after learning a strict set of actions, they are well able to imitate novel but related arbitrary gestures (Custance et al. 1995). Interestingly, deferred imitation has also been found. Deferred imitation of novel actions was also found in dogs with retention intervals of 1.5 min and memory of familiar actions with intervals ranging from .40 to 10 min. In other animals, deferred imitation is not only based on sensorimotor-related stimuli. For example, observer budgerigars accessed a stopper immediately or 24 h after the observers had watched a video of a conspecific model either pecking or stepping on the stopper to obtain access to food. The observers performed the action they had observed, pecking or stepping, with higher frequency in both immediate as well as deferred imitation, suggesting that budgerigars are capable of “deferred imitation” or “imitation from memory (Richards et al. 2009),” a capacity previously thought to be uniquely human (Meltzoff and Moore 1994).
In summary, this entry has briefly discussed important topics in the light of underlying mechanisms of deferred and immediate imitation. First, there is little evidence that a specialized imitation system enables immediate imitative behavior, while deferred imitation is based on more complex cognitive behavior. Rather, imitation always includes perceived outcomes of actions beyond simple S-R mappings. Additionally, evidence is lacking that early immediate imitation is initiated before active experiences are collected. Second, the supposed underlying mirror neuron mechanism is not serving immediate imitation only. The system includes higher cognitive representations such as outcome expectancies and also heavily relies on experiences. Finally, findings from comparative studies suggest that imitation goes beyond simple S-R mappings. Birds as well as other animals are found to be sensitive to rewards like food, which modulate immediate as well as deferred imitation. To conclude, humans are gifted imitators, and the capacity to defer imitation in the absence of the observed model marks us as members of particular cultural groups and contributes to cultural evolution, the accumulation of knowledge and improvement of skills over generations. However, the mechanisms that make imitation possible are not likely to be an inborn, special imitative system. Rather, we are great imitators, Homo imitans, as we can use previous experiences in a given situation to create the likely consequences of performing the action observed in others.
- McDonough, L., Mandler, J. M., McKee, R. D., & Squire, L. R. (1995). The deferred imitation task as a nonverbal measure of declarative memory. Proceedings of the National Academy of Sciences of the United States of America, 92(16), 7580–7584. https://doi.org/10.1073/pnas.92.16.7580.CrossRefPubMedPubMedCentralGoogle Scholar
- Rizzolatti, G., & Craighero, L. (2004). The mirror-neuron system. Annual Review of Neuroscience, 27, 169–192. https://doi.org/10.1146/annurev.neuro.27.070203.144230.CrossRefPubMedGoogle Scholar
- Wohlschläger, A., Gattis, M., & Bekkering, H. (2003). Action generation and action perception in imitation: An instance of the ideomotor principle. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 358(1431), 501–515. Retrieved from http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1693138&tool=pmcentrez&rendertype=abstract