The Mystery of How Newborns Can Imitate Has Been Solved
Humans appear to be unique in the extent upon which we rely on culture: on the tools, words and ideas we acquire from others. Through imitation and teaching, culture functions as a second inheritance system over and above biological inheritance. It has even been argued that we have biologically evolved for cultural evolution, as we appear to be born with a capacity to imitate. While it had remained mysterious how a newborn would instantly be able to match what it sees others do with its own motor actions, neonatal imitation had become central to many theories about normal social cognitive development. This claim that even newborn humans can copy, however, has now been seriously challenged.
The largest longitudinal study on neonatal imitation
For over four decades, parents have been told that their newborn babies can imitate their gestures. The most common gesture reported was tongue poking: Poke out your tongue and the little ones stick out theirs in turn. One of my babies seemed to do just that, whereas the other one showed no signs of copying at all. Like other parents, I wondered if I should worry about whether my baby does or does not appear to have such an early tendency to imitate. In collaboration with Virginia Slaugther, Janine Oostenbroek, Jon Redshaw and others our laboratory at the University of Queensland set out to examine individual differences in “neonatal imitation” in the largest ever longitudinal study to assess what it may predict about later social learning and cognition.
However, we were surprised to find no compelling evidence of neonatal imitation at all. Yes, sometimes infants would poke out their tongue when we had done the same, but children were just as likely to do so in response to other gestures. This was an unwelcome finding as we had hoped to track what individual differences in imitation might predict throughout development. But the data were compelling. While there had been previous failures to replicate neonatal imitation – no other study had so comprehensively tested this purported ability.
Re-assessing previous studies
Following our study, a debate ensued in the literature about whether differences in methodology may explain why some studies find an effect and others do not. We therefore conducted a comprehensive meta-analysis to assess the role of these methodological factors. Examining data from the last 40 years comprising over 300 effect sizes, we found that only a select group of laboratories report finding the effect, and they do not appear to do so because of any particular methods used.
Could it really be the case that the long-celebrated phenomenon is not real? Diverse other lines of evidence now bolster this conclusion. EMG studies now suggest that imitation first emerges not at birth but between four and seven months of age. A compelling analysis of human aero-digestive development concluded that human neonates do not even possess voluntary cortical control over facial actions that were supposed to have been imitated. Belief in the reality of neonatal imitation was previously supported by reports that newborn macaques imitate facial gestures too. But this case has also been undermined by a statistically robust re-analysis of all published macaque data yielding no sign of imitation.
Is this issue settled then?
It is quite likely that future studies will continue to sporadically find apparent signs of neonatal imitation. To make a difference, however, such new evidence needs to be more powerful than the addition of merely another small dataset. I believe that only large-scale, multi-lab, pre-registered replication studies can shift the current weight of the evidence. As it stands, I think it is time to rewrite the textbooks: There is no compelling case that newborns can imitate.
This need not mean that imitation is not in our genes, as one commentator has argued. After all, not all innate traits have to be present at birth (just think about puberty). But it does mean that parents can stop worrying about their newborns not copying parental gestures.