infant development study guide

Developmental Science. 2019;00:e12892. wileyonlinelibrary.com/journal/desc  |  1 of 13 https://doi.org/10.1111/desc.12892

© 2019 John Wiley & Sons Ltd

1   |   I N T R O D U C T I O N

Imitation plays a critical role in human social learning and cultural traditions (see, e.g. Boyd & Richerson, 1996; Henrich & McElreath, 2003; Legare & Nielsen, 2015; Tomasello, Kruger, & Ratner, 1993), and so charting its ontogeny is of great importance to integrative theories of social cognitive development. An innate propensity to imitate from birth would suggest that human brains are pre‐wired

with a solution to the “correspondence problem” of coordinating one's own and others’ actions (Brass & Heyes, 2005). Most remark‐ ably, it would suggest that we are born with a capacity to link our own felt but unseen facial actions with the seen but unfelt facial ac‐ tions of others. Alternatively, if newborns do not imitate, then it would appear that we instead acquire the capacity during infancy (Piaget, 1962), perhaps as a function of both innate and environmen‐ tal factors (see, e.g. Bjorklund, 2018; Byrne, 2003; Heyes, 2016a;

Received: 11 February 2019  | Revised: 20 May 2019  | Accepted: 23 July 2019 DOI: 10.1111/desc.12892

P A P E R

Individual differences in neonatal “imitation” fail to predict early social cognitive behaviour

Jonathan Redshaw1  | Mark Nielsen1,2  | Virginia Slaughter1  | Siobhan Kennedy‐ Costantini1,3  | Janine Oostenbroek1 | Jessica Crimston1  | Thomas Suddendorf1

1School of Psychology, University of Queensland, Brisbane, Australia 2Faculty of Humanities, University of Johannesburg, Johannesburg, South Africa 3School of Psychology, University of Auckland, Auckland, New Zealand

Correspondence Jonathan Redshaw, School of Psychology, University of Queensland, Brisbane, Australia. Email: [email protected]

Funding information Australian Research Council, Grant/ Award Number: DP0985969; University of Queensland, Grant/Award Number: UQFEL1832633

Abstract The influential hypothesis that humans imitate from birth – and that this capacity is foundational to social cognition – is currently being challenged from several angles. Most prominently, the largest and most comprehensive longitudinal study of neona‐ tal imitation to date failed to find evidence that neonates copied any of nine actions at any of four time points (Oostenbroek et al., [2016] Current Biology, 26, 1334–1338). The authors of an alternative and statistically liberal post‐hoc analysis of these same data (Meltzoff et al., [2017] Developmental Science, 21, e12609), however, concluded that the infants actually did imitate one of the nine actions: tongue protrusion. In line with the original intentions of this longitudinal study, we here report on whether individual differences in neonatal “imitation” predict later‐developing social cogni‐ tive behaviours. We measured a variety of social cognitive behaviours in a subset of the original sample of infants (N = 71) during the first 18 months: object‐directed imitation, joint attention, synchronous imitation and mirror self‐recognition. Results show that, even using the liberal operationalization, individual scores for neonatal “imitation” of tongue protrusion failed to predict any of the later‐developing social cognitive behaviours. The average Spearman correlation was close to zero, mean rs = 0.027, 95% CI [−0.020, 0.075], with all Bonferroni adjusted p values > .999. These results run counter to Meltzoff et al.'s rebuttal, and to the existence of a “like me” mechanism in neonates that is foundational to human social cognition.

K E Y W O R D S

cognitive development, correspondence problem, like me framework, mirror neurons, neonatal imitation, social cognition

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Paulus, Hunnius, Vissers, & Bekkering, 2011; Ray & Heyes, 2011). Mirror neurons have been proposed as a neural correlate of imitation (Iacobini, 2009), but it remains controversial whether these neurons play an innate and causal role in copying behaviour (Ferrari, Bonini, & Fogassi, 2009; Simpson, Murray, Paukner, & Ferrari, 2014a) or whether they are simply an artefact of postnatal associative learning (Cook, Bird, Catmur, Press, & Heyes, 2014; Heyes, 2010).

Mid‐20th century theorists considered an innate solution to the correspondence problem to be unlikely, instead suggesting that the capacity for imitation is acquired late during the first year of life (Piaget, 1962; Uzgiris & Hunt, 1975). The paradigm shifted, however, following Meltzoff and Moore's (1977) report of imitation in infants under three weeks of age. This result was soon followed by another influential finding of imitation in the initial days of life (Field, Woodson, Greenberg, & Cohen, 1982), and it was thus gen‐ erally concluded that infants do indeed possess an innate solution to the correspondence problem. The phenomenon of neonatal imi‐ tation has since been incorporated not only into leading theories of cognitive development (Meltzoff, 2007; Nadel & Butterworth, 1999; Trevarthen & Aitken, 2001), but also into theories of social psychol‐ ogy (Cheng & Chartrand, 2003; Lakin, Jefferis, Cheng, & Chartrand, 2003), comparative psychology (Iacobini, 2009; Simpson, Paukner, Suomi, & Ferrari, 2014b) and neuroscience (Gallese, 2001; Meltzoff & Decety, 2003).

The dominant theory of neonatal imitation's function is the like me framework (Meltzoff, 2005, 2007; Meltzoff & Brooks, 2001), which suggests that an innate capacity for copying others is the “engine and mechanism for the growth of social cognition” (Meltzoff, 2005, pp.7). This framework interprets infants’ imitative acts in richer, cognitive terms than alternative, behaviour‐based frameworks of imitation (see Moore, 2013; Paulus, 2011). In particular, the like me framework proposes that infants represent their own and others’ action sequences using the same supra‐modal mental code, allow‐ ing them to infer equivalences between their own and others’ inter‐ nal states, such as perceptions, intentions and emotions (Meltzoff, 2007). One implication of this framework, then, is that neonates who are more proficient imitators might be expected to show earlier and more robust social cognitive aptitudes than their peers who are less proficient imitators (Heimann, 2002; Heimann, Nelson, & Schaller, 1989; Simpson, Murray, et al., 2014a; Suddendorf, Oostenbroek, Nielsen, & Slaughter, 2013). In other words, if neonatal imitation pro‐ vides the bedrock for later emerging social cognitive abilities, then individual differences in neonatal imitation should predict individual differences in later‐developing forms of imitation and other social cognitive behaviours (but see Bjorklund, 1987).

Heimann et al. (1989) were the first to test for such associations in a short‐term longitudinal study. Imitation of tongue protrusion and mouth opening was assessed in 32 infants at three time points − 2 to 3 days, 3 weeks and 3 months – with mixed results. Imitation ef‐ fects were only significant for tongue protrusion (at the first two time points), and only when the definition of this behaviour was broadened to include actions where “the tongue was not protruded beyond the lips”. Furthermore, although there were some significant

correlations between tongue protrusion imitation scores across the first two time points, these correlations were based on a separate, very narrow definition of tongue protrusion, for which the infants did not show significant evidence of imitation above chance levels. The authors concluded that a more comprehensive longitudinal ap‐ proach was needed to provide “an answer to one of the most import‐ ant questions remaining: How [do] individual differences in neonatal imitation relate to later imitation seen around 9–18 months of age?” (Heimann et al., 1989, pp. 100). Despite this call to action coming 30 years ago, to date there exist no published longitudinal studies assessing the relationship between neonatal imitation and later im‐ itative and other social cognitive capacities in humans. The founda‐ tional assumption of the like me framework has therefore not been empirically established.

We originally set out to conduct just this kind of long anticipated longitudinal investigation (Suddendorf et al., 2013). We measured imitation of nine modelled social actions at four time points between 1 and 9 weeks of age, hoping to eventually examine whether individ‐ ual differences in neonatal imitation aligned with individual differ‐ ences in other social cognitive behaviours that we measured during the early years of life. To our surprise, however, we did not find evi‐ dence of neonatal imitation in our initial measure at all—not for any of the nine actions at any of the four time points (Oostenbroek et al., 2016). We were compelled to conclude, therefore, that rather than providing the foundation for a definitive study of neonatal im‐ itation's function, our data instead challenged the very existence of neonatal imitation itself. This unforeseen conclusion has since been substantiated by several other works:

1. A comprehensive sensorimotor analysis suggesting that neonates lack voluntary, cortical control over tongue protrusion, thus making intentional imitation of this action implausible (Keven & Akins, 2017);

Research Highlights • A previous large‐scale longitudinal study reported no

evidence of neonatal imitation for any of nine actions at any of four time points.

• A post hoc, statistically liberal re‐analysis of these same data, however, suggested that the neonates may have actually imitated one of the nine actions: tongue protrusion.

• We tested for associations between this operationali‐ zation of tongue protrusion imitation and various later‐ developing social cognitive behaviours in the original sample of infants.

• There were no significant correlations between neo‐ natal “imitation” scores and any later‐developing social cognitive behaviours, controverting the dominant like me framework of neonatal imitation's function.

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2. A study suggesting that previously blind, newly sighted children show greatly impaired automatic imitation of manual actions, meaning that this capacity is either not innate or vulnerable to degradation in specific domains (McKyton, Ben‐Zion, & Zohary, 2018);

3. A study showing that mothers’ tendency to imitate their 4‐month‐ old infants’ actions predicted these infants’ own rudimentary signs of imitation (measured by EMG), suggesting that infants may learn to imitate via repeated associative pairings of their own and others’ actions (de Klerk, Lamy‐Yang, & Southgate, 2018);

4. A systematic meta‐analysis suggesting that automatic imitation in adults is also best explained by an associative learning framework (Cracco et al., 2018), meaning that the existence of neonatal imi‐ tation would require the non‐parsimonious addition of a second, innate mechanism to explain the same phenomenon;

5. A statistically robust re‐analysis of data previously used to sup‐ port the existence of neonatal imitation in rhesus macaques (Paukner, Pederson, & Simpson, 2017), showing that neonatal macaques have in fact failed to produce imitative actions at levels greater than chance (Redshaw, 2019);

6. A study suggesting that newborn primates are not born with an innate capacity to recognize faces, meaning they would be un‐ able to link the actions of other faces with those of their own face (Arcaro, Schade, Vincent, Ponce, & Livingstone, 2017); and

7. An unpublished PhD thesis that similarly found no evidence of neonatal imitation in a longitudinal study of 90 human infants measured at four time points (Barbosa, 2017).

Despite these dovetailing discoveries, researchers who have previ‐ ously published positive findings of neonatal imitation have defended their results by questioning the validity of our longitudinal study. Thirteen prominent neonatal imitation researchers published a rebut‐ tal (Meltzoff et al., 2017), in which they made two seemingly contradic‐ tory arguments: (a) our study was too methodologically flawed to detect imitation effects, but also (b) our data do in fact contain evidence for neonatal imitation of tongue protrusion. In a response (Oostenbroek et al., 2018), we outlined why the so‐called “flaws” were inconsistent with our actual patterns of results, inconsistent with broader findings in the literature, and/or incompatible with earlier claims made by Meltzoff and others. For instance, Meltzoff et al. (2017, pp. 6) argued that having an unfamiliar model is the “key” to eliciting neonatal imitation, despite earlier reports that the phenomenon “did not vary as a function of fa‐ miliarity with the model” (Meltzoff & Moore, 1992, pp. 479).

Here, we focus on the second prong of Meltzoff et al.'s (2017) rebuttal. In their post‐hoc re‐analysis of our data, the authors showed that infants’ frequencies of tongue protrusion in response to the tongue protrusion model were significantly greater than their average frequencies of tongue protrusion in response to the other 10 control models (which included dynamic faces, manual actions, object actions and verbalizations). In our original analy‐ ses, by contrast, we conducted pairwise comparisons showing that infants failed to significantly protrude their tongues more often in response to the tongue protrusion model than in response to

the mouth opening, happy face, and sad face models. The logic for conducting pairwise comparisons is to guard against the sim‐ ple possibility that certain categories of control models (e.g. dy‐ namic faces) might elicit higher levels of tongue protrusion than others (Oostenbroek et al., 2018). If so, then one might expect a significant finding of “imitation” when averaging across all control models, even if infants are not in fact matching the specific action (see Meltzoff & Moore, 1977; Paukner et al., 2017, for similar ar‐ guments). Meltzoff et al.'s (2017) re‐analysis also disregards the gold standard "cross‐target" approach (Meltzoff, 1996; Meltzoff & Moore, 1977), which requires that infants demonstrate flexibility in matching responses across multiple actions before evidence for imitation is declared.

Nevertheless, by claiming that our data contain evidence for tongue protrusion imitation, Meltzoff et al. (2017) are in effect for‐ mulating a testable hypothesis for the dominant like me framework (Meltzoff, 2005, 2007). That is, if (a) the infants in our sample were in fact imitating tongue protrusion, and (b) the like me framework is correct, then (c) Meltzoff et al.'s operationalization of tongue pro‐ trusion imitation should be associated with later imitation and other social cognitive behaviours in our sample (Heimann et al., 1989; Suddendorf et al., 2013). Given that we had originally planned to test for such associations, we had in fact collected data on social cognitive behaviours from many of our participants over the first 18 months of life. Although there was little point in conducting cor‐ relations following our reported results (as they yielded no signs of neonatal imitation), we are now able to test for associations in light of Meltzoff et al.'s (2017) re‐analysis.

We therefore examined relationships between Meltzoff et al.'s (2017) operationalization of tongue protrusion imitation and: (a) object‐directed imitation measured at 6, 9, 12 and 18 months, (b) joint attention measured at 9 and 12 months, (c) synchronous imitation measured at 18 months, and (d) mirror self‐recognition measured at 18 months. We originally selected this wide range of measures in order to test the strong continuity and general‐ izability claims at the heart of the like me framework: that neo‐ natal imitation sits at the foundation of not only later‐developing forms of imitation, but also human social cognition in the broader sense (Meltzoff, 2005, 2007; Meltzoff & Brooks, 2001). Both object‐directed imitation (e.g. Carpenter, Nagell, & Tomasello, 1998; Nielsen, 2006) and synchronous imitation (e.g. Asendorpf, Warkentin, & Baudonniere, 1996; Nielsen & Dissanayake, 2004) gradually emerge over the initial two years of life, and if these abilities are indeed continuous with the supposed capacity for neonatal imitation, then we might expect to find significant cor‐ relations with Meltzoff et al.'s (2017) operationalization of tongue protrusion imitation. Similarly, both joint attention (e.g. Corkum & Moore, 1998; Johnson, Slaughter, & Carey, 1998) and mirror self‐ recognition (e.g. Gallup, 1970; Suddendorf & Butler, 2013) develop during infancy, and if these broader social cognitive abilities are indeed supported by the same mechanisms as neonatal imitation, then we likewise might expect correlations with Meltzoff et al.'s (2017) operationalization.

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2   |   M E T H O D

2.1 | Participants

Participants included 71 of the original sample of 106 infants from Oostenbroek et al.'s (2016) study. The remaining 35 original partici‐ pants were assessed at neonatal time points only as part of the PhD project of one of the authors (JO), and were never intended to form part of the larger longitudinal assessment. The final 71 infants in‐ cluded 38 females and 33 males. All participants were born full‐term, with a mean gestational age of 39.88 months (SD = 1.22 months, range = 36.6–43.0 months). Mean birth weight was 3.59 kg (SD = 0.43 kg, range = 2.54–4.60 kg), and 51 infants were delivered vaginally (20 via Caesarean section).

The large majority of these 71 infants contributed data to the neonatal imitation measure at 1 week (n = 61), 3 weeks (n = 63), 6 weeks (n = 66) and 9 weeks (n = 64), and on the other social cog‐ nitive measures at 6 months (n = 70), 9 months (n = 70), 12 months (n = 69) and 18 months (n = 69). Infants who did not contribute data at a given time point were excluded from all analyses involving the variables measured at that time point.

2.2 | Measures

2.2.1 | Neonatal tongue protrusion “imitation”

Comprehensive details of the neonatal imitation measure are in‐ cluded in the Appendix S1 of Oostenbroek et al. (2016). In brief, infants were exposed to 1‐minute demonstrations of 11 separate modelled actions at 1, 3, 6 and 9 weeks of age. These 11 actions included oral gestures (tongue protrusion, mouth opening), object actions analogous to the oral gestures (a spoon protruding through a tube, a box opening), facial expressions (happy face, sad face), manual gestures (index finger pointing, grasping) and verbaliza‐ tions (mmm sound, eee sound, tongue click sound). We subsequently coded how frequently infants produced each of these gestures (ex‐ cluding the object actions) in response to each of the modelled dem‐ onstrations. Given that Meltzoff et al. (2017) only suggest that the tongue protrusion gesture was imitated in the sample, we limit our current analysis to this gesture.

Scoring

Following Meltzoff et al.'s (2017) operationalization, infants’ tongue protrusion “imitation” scores at 1, 3, 6 and 9 weeks were calculated by subtracting the mean frequency of tongue protrusions in response to non‐matching models from the frequency of tongue protrusions in response to the matching model. The mean frequency was typi‐ cally calculated across all 10 control models, although in some cases the infant was not exposed to all 10 controls (e.g. because they were not alert enough to complete the duration of the experiment) and so the mean represented the frequency of tongue protrusions in re‐ sponse to a more limited selection of controls. A positive score on this variable indicated that the infant showed a greater propensity

to protrude their tongue in response to the tongue protrusion model than to other models on average. Infants who did not see the tongue protrusion model at a given time point were excluded from all analy‐ ses involving that time point.

2.2.2 | Object‐directed imitation

Each infant was administered three separate object‐directed imita‐ tion tasks, broadly similar to those developed by Carpenter et al. (1998), at each of 6, 9, 12 and 18 months of age. During all tasks, the infant was seated on their caregiver's lap at a table directly across from the experimenter. Infants could receive either 0, 1 or 2 points for each task, and the presentation order of all tasks was counterbal‐ anced across infants and time points.

For the door opening task, the experimenter placed on the table a box apparatus with two openable doors at the front. The exper‐ imenter opened one of the doors, retrieved a toy from inside and showed it to the infant before placing it back inside and closing the door. The experimenter then repeated this series of actions five times in total, never opening or touching the second door. Finally, the experimenter pushed the apparatus towards the infant. We coded whether or not the infant opened the target door (0 or 1 point) and whether or not they touched the toy inside (0 or 1 point) at any time before the end of the 60 s trial.

For the rattle task, the experimenter placed on the table two small lidded containers. The experimenter picked up one of the con‐ tainers and shook it to make a rattling sound, and then placed the container back on the table. The experimenter repeated this series of actions five times in total, never picking up and shaking the second container. Finally, the experimenter pushed the containers towards the infant. We coded whether or not the infant touched the target container (0 or 1 point) and whether or not they shook the target container (0 or 1 point) at any time before the end of the 60 s trial.

For the circular container task, the experimenter placed on the table a circular red container with a green lid. The experimenter opened the lid and placed it next to the container, before retrieving a toy from the container. As the experimenter lifted the toy, she began rattling it to produce a sound before placing it on the table next to the container. She then lifted the toy up again and began rattling it before placing it back into the container. The experimenter repeated this series of actions five times in total, never touching the lid of the container. Finally, the experimenter pushed the open container, the lid and the toy (which was also on the table) towards the infant. We coded whether or not the infant touched the toy (0 or 1 point) and whether or not they shook the toy and placed it into the container (0 or 1 point) at any time before the end of the 60 s trial.

Scoring

For each infant at each time point, we first calculated an average score across the door opening, rattle and circular container tasks (range = 0–2). We then divided this initial score by 2 to give a stand‐ ardized continuous score between 0 and 1. For infants whose data were missing for one or two of the tasks at a given time point, these

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averages were calculated across the tasks without missing data (such that the final standardized score still ranged between 0 and 1).

2.2.3 | Joint attention

Each infant was administered three separate joint attention tasks at each of 9 and 12 months of age (see, e.g. Behne, Liszkowski, Carpenter, & Tomasello, 2012; Carpenter et al., 1998; Slaughter & McConnell, 2003). During the first two tasks, the infant was seated on their caregiver's lap at a table directly across from the experi‐ menter. For the gaze following task, the experimenter first captured the infant's attention, before looking to her left at a picture on the wall and making a surprised exclamation. The experimenter briefly looked back at the child, before again looking to her left for approxi‐ mately 15 s. The experimenter then repeated this exact sequence of actions for a picture on the wall to her right (the order of gaze direction was counterbalanced across infants). We coded whether or not the infant followed the experimenter's gaze to the left with a full head turn (0 or 1 point), and whether or not the infant followed the experimenter's gaze to the right with a full head turn (0 or 1 point). The infant could thus receive a score of 0, 1, or 2 for gaze following.

For the gaze and point following task, the experimenter first cap‐ tured the infant's attention, before turning to her right and pointing at a picture on the wall and making a surprised exclamation. After approximately 15 s, the experimenter returned her hand to a normal position and again captured the infant's attention. The experimenter then turned her head to her left and pointed at a picture on the wall while making a surprised exclamation (the order of pointing direc‐ tion was counterbalanced across infants). We coded whether or not the infant followed the experimenter's point to the left with a full head turn (0 or 1 point), and whether or not the infant followed the experimenter's point to the right with a full head turn (0 or 1 point). The infant could thus receive a score of 0, 1, or 2 for gaze and point following.

For the point production task, the infant sat at a table next to the main experimenter, who was looking at a book and ignoring the infant. Meanwhile, a second experimenter – who was unseen and standing behind a black curtain in front of the infant – pushed two rattles through the curtain one at a time (one on the left, one on the right) and shook them loudly for approximately 15 s each. We coded whether or not the infant tried to get the attention of the main ex‐ perimenter by pointing in the same direction as the rattle on the left (0 or 1 point) and the rattle on the right (0 or 1 point). Infant pointing actions had to be judged as intentional by the coder to receive a score of 1. The infant could thus also receive a score of 0, 1, or 2 for point production.

Scoring

For each infant at each time point, we first calculated an average score across the gaze following, gaze and point following, and point production measures (range = 0–2). We then divided this initial score by 2 to give a standardized continuous score between 0 and 1. Combining the measures into a single score in this way was justified

by the fact that previous studies have found correlations between gaze/point following and point production (e.g. Behne et al., 2012; Carpenter et al., 1998), consistent with the existence of a general “joint attention” construct. For infants whose data were missing for one or two of the gaze following, point following, or point produc‐ tion measures at a given time point, these averages were calculated across the tasks without missing data (such that the final standard‐ ized score still ranged between 0 and 1). Six infants who participated in the study at 9 months provided no data for any joint attention tasks and so were excluded from all analyses involving joint atten‐ tion at that time point.

2.2.4 | Synchronous imitation

Each infant was administered four separate synchronous imita‐ tion tasks at 18 months of age (see, e.g. Asendorpf et al., 1996; Nielsen & Dissanayake, 2004). During all tasks, the infant was seated on their caregiver's lap at a table directly across from the experimenter. Prior to each task, the experimenter produced two identical toys, placing one in front of herself and one in front of the infant.

For each task, the experimenter repetitively produced two ac‐ tions for approximately 15 s (five times each for approximately 3 s each time). In the mug task, the experimenter tapped the bottom of a cup and turned it on its end. In the hammer task, the experimenter flipped a toy hammer side to side and then tapped the handle with her hand. In the toothbrush task, the experimenter pretended to brush her hair and then brushed her arm. In the saw task, the exper‐ imenter pretended to saw her hand and then tapped the blade of the saw on the palm of her hand. For each of these tasks, we coded whether or not the infant produced each of the two experimenter actions simultaneously with the experimenter (0 or 1 point for each action, with a range of 0–2 for each task).

Scoring

For each infant, we first calculated an average score across the mug, hammer, toothbrush and saw tasks (range = 0–2). We then divided this initial score by 2 to give a standardized continuous score be‐ tween 0 and 1. For infants whose data were missing for between one and three of the tasks, the average was calculated across the tasks without missing data (such that the final standardized score still ranged between 0 and 1).

2.2.5 | Mirror self‐recognition

Each infant was administered the mark test for mirror self‐recog‐ nition at 18 months of age. The experimenter directed the infant's attention towards a large mirror for a familiarization period of ap‐ proximately 30 s (or until the infant had looked directly at the mirror), before covering up the mirror with a black sheet. The experi‐ menter then surreptitiously placed a sticker on the infant's forehead before uncovering the mirror. We coded whether or not the infant actively touched the sticker or a region within 2cm of it (score of 0 or

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1) before approximately 20 s had passed (see Nielsen & Dissanayake, 2004).

2.3 | Procedure

Details of the neonatal testing procedure are reproduced in the Appendix S1 of Oostenbroek et al. (2016). For the later measures, all testing was conducted in laboratories in the School of Psychology at the University of Queensland in Brisbane, Australia. Each session lasted approximately 45–60 min in total.

2.4 | Coding reliability

See the Appendix S1 of Oostenbroek et al. (2016) for comprehensive coding reliability information for the neonatal imitation measure. All later developing social cognitive variables were coded by a trained research assistant (JC). Twenty percent of the data were also coded by a blind and independent rater for reliability purposes. Inter‐rater reliability was excellent (Cicchetti, 1994) for five of the eight meas‐ ures, with intraclass correlation coefficients ranging from 0.808 to 0.935. Reliability was good for one measure (object‐directed imi‐ tation at 12 months) and fair for the other two measures (joint at‐ tention at 9 months and synchronous imitation at 18 months), with intraclass correlation coefficients of 0.680, 0.515 and 0.520. Full reliability data are reproduced in the Appendix S1.

3   |   R E S U LT S

3.1 | Patterns of results within each task

3.1.1 | Tongue protrusion “imitation” between 1 and 9 weeks

As seen in Figure 1, infants’ tongue protrusion “imitation” scores were consistently greater than zero, which is broadly consistent with Meltzoff et al.'s (2017) re‐analysis. One sample t‐tests, however, re‐ vealed that these scores were not significantly greater than zero at 1 week, t (60) = 1.09, p = .278, 3 weeks, t (62) = 1.21, p = .230, or

6 weeks, t (65) = 1.49, p = .140. Only at 9 weeks were scores signifi‐ cantly above zero, t (63) = 2.59, p = .012. The non‐significant results from the first three time points may reflect the fact that this sample of infants included a smaller subset of Oostenbroek et al.'s (2016) original sample. Although Figure 1 may give the impression that tongue protrusion “imitation” scores increased over time, a post‐hoc repeated measures ANOVA on the infants who contributed data to all time points revealed that this apparent trend was not significant, linear F (1, 45) = 2.53, p = .119. When averaging across all time points, tongue protrusion “imitation” scores were significantly greater than zero, t (70) = 3.19, p = .002.

3.2 | Later developing social cognitive variables

3.2.1 | Mean scores and change over time

Infants’ standardized mean scores for object‐directed imitation (6, 9, 12 and 18 months), joint attention (9 and 12 months), synchronous imitation (18 months) and mirror self‐recognition (18 months) are presented in Figure 2. Repeated measures ANOVAs confirmed that object‐directed imitation scores significantly increased with age, lin‐ ear F (1, 65) = 160.46, p < .001, and that joint attention scores sig‐ nificantly increased from 9 months to 12 months, F (1, 62) = 59.85, p < .001. These patterns are consistent with those seen in previous studies (see, e.g. Mundy et al., 2007; Nielsen & Dissanayake, 2004).

3.2.2 | Variation in scores

Figure 3 shows the frequency histograms for children's scores on each of the social cognitive measures at each time point. This figure demonstrates that nearly all infants showed at least minimal signs of object‐directed imitation and joint attention at all measured time points, although at no time did the majority of infants score at ceil‐ ing (i.e., a score of 1) on any measure. The figure also demonstrates that just over half of the infants showed at least minimal evidence of synchronic imitation at 18 months (with none performing at or close to ceiling), and just under half showed evidence of mirror self‐recog‐ nition at the same time point. Overall, these histograms indicate that we were observing the behaviours at rates in line with past studies (e.g. Nielsen & Dissanayake, 2004), and when infants were at a wide variety of competence levels. Presumably, we therefore had a good chance of detecting correlations if they are indeed present in the population.

3.3 | Associations between different measures

3.3.1 | Consistency of tongue protrusion “imitation” across time points

Table 1 shows the Spearman correlations between infants’ tongue protrusion “imitation” scores across neonatal time points, as an as‐ sessment of intra‐individual consistency in the measure proposed by Meltzoff et al. (2017). Correlation values ranged from −0.210 to

F I G U R E 1   Mean tongue protrusion "imitation" scores across the first 9 weeks. Scores were calculated using Meltzoff et al.’s (2017) suggested method. Error bars indicate standard error of the mean, and asterisks indicate scores that are significantly greater than zero

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0.253, and a one sample t‐test indicated that the mean correlation size (rs = 0.001, 95% CI [−0.179, 0.181]) did not significantly differ from zero, t (5) = 0.014, p = .989.

The scaled JZS Bayes Factor in favour of the null hypothesis was equal to 2.68, suggesting that the mean correlation was 2.68 times more likely to be observed under a true null hypothesis than a true alternative hypothesis. None of the correlations were significant after applying a Bonferroni correction, all adjusted p > .30, nor were any significant after applying the more liberal Benjamini‐Hochberg (q = 0.05) correction (see Table S5). On the whole, there was nothing to suggest intra‐individual consistency in “imitation” scores. Namely, there was nothing to suggest that infants who scored higher at any given time point on Meltzoff et al.'s (2017) operationalization of

neonatal imitation also scored systematically higher on this variable at other time points, as would be expected if it were truly measuring a fundamental social cognitive capacity. Rather, the data are con‐ sistent with our interpretation that this operationalization does not measure true imitation or any other construct of importance.

3.3.2 | Relationships between tongue protrusion “imitation” and later social cognitive variables

Table 2 shows the Spearman correlations between neonatal tongue protrusion “imitation” scores and the later developing social cogni‐ tive variables, as an assessment of predictions following from the like me framework (Meltzoff, 2005, 2007). Correlation values ranged

F I G U R E 2   Standardized mean scores for social cognitive variables over the first 18 months, with error bars indicating standard error of the mean. The object‐ directed imitation, joint attention and synchronous imitation scores were calculated according to the criteria outlined in the methods. The mirror self‐recognition score represents the proportion of infants who passed the mark test

0

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0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

6 9 12 18 0(

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M desidradnatS

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Age (months)

object-directed imita�on

joint a�en�on

synchronous imita�on

mirror self-recogni�on

F I G U R E 3   Frequency histograms for social cognitive variables over the first 18 months. Object‐directed imitation (ODI), joint attention (JA) and synchronous imitation (SI) scores are on continuous scales, whereas mirror self‐recognition (MSR) scores are categorical

8 of 13  |     REDSHAW Et Al.

from −0.208 to 0.270, and a one sample t‐test indicated that the mean correlation size (rs = 0.027, 95% CI [−0.020, 0.075]) did not sig‐ nificantly differ from zero, t (31) = 1.17, p = .250.

The scaled JZS Bayes Factor in favour of the null hypothesis was equal to 2.84, suggesting that the mean correlation was 2.84 times more likely to be observed under a true null hypothesis than a true alternative hypothesis. None of the correlations were significant after applying a Bonferroni correction, all adjusted p > .999, nor were any significant after applying a more liberal Benjamini‐Hochberg (q = 0.05) correction (see Table S5). Overall, there was nothing to suggest that infants who scored higher at any time point on Meltzoff et al.'s (2017) operationalization of neonatal imitation also scored systematically higher on the other later‐measured social cognitive variables, as would be expected under the like me framework of neo‐ natal imitation (Meltzoff, 2005, 2007). Again, the data are consistent with our interpretation that this operationalization does not reflect true imitation, and that the like me framework is controverted.

3.4 | Post‐hoc exploratory analyses

Following suggestions from peer reviewers, we performed two se‐ ries of additional, exploratory analyses of our data. Although neither series of analyses has a direct bearing on the validity of the like me framework, they do provide (post‐hoc) tests of alternative hypoth‐ eses regarding the early development of social cognition in our large sample of infants.

3.4.1 | Consistency and predictive value of neonates’ tendency to protrude the tongue in response to facial gestures

Bjorklund (2018) recently highlighted that the neonates in our origi‐ nal study consistently displayed tongue protrusions in response to facial gestures (compared to other models), and suggested that such a tendency might serve to maintain face‐to‐face interactions be‐ tween infants and their caregivers. We therefore examined whether the neonates showed intra‐individual consistency in this tendency across neonatal time points, and whether individual differences pre‐ dicted later‐developing social cognitive behaviour. For each neonatal time point in the original full sample from Oostenbroek et al. (2016), we first obtained a “face‐specific tongue protrusion score” by calcu‐ lating the difference between (a) the average frequency of tongue protrusions in response to the facial gesture models (tongue protru‐ sion, mouth opening, happy face, sad face) and (b) the average fre‐ quency of tongue protrusions in response to the seven other models. Supporting Bjorklund's (2018) observations, a series of one‐sample t‐tests indicated that these scores were significantly above zero at 3 weeks, t (92) = 4.52, p < .001, 6 weeks, t (100) = 3.58, p = .001 and 9 weeks of age, t (95) = 3.49, p = .001, and above zero but not signifi‐ cantly so at 1 week of age, t (87) = 1.88, p = .063.

T A B L E 1   Spearman correlations among tongue protrusion “imitation” scores across neonatal time points

1 week 3 weeks 6 weeks 9 weeks

1 week ‐ −0.210 −0.157 0.121

3 weeks – −0.013 0.012

6 weeks – 0.253

9 weeks –

Note: No correlations were significant after Bonferroni or Benjamini‐ Hochberg corrections were applied. Correlation colour scale. −1 1.

Social cognitive variables

Tongue protrusion “imitation” scores

1 week 3 weeks 6 weeks 9 weeks

Object‐directed imitation (6 months)

0.190 −0.041 0.244 0.214

Object‐directed imitation (9 months)

−0.208 0.119 −0.006 0.008

Object‐directed imitation (12 months)

0.082 0.084 −0.148 0.050

Object‐directed imitation (18 months)

−0.073 −0.098 −0.003 0.077

Joint attention (9 months) 0.202 −0.094 0.143 0.208

Joint attention (12 months) −0.089 −0.056 0.123 0.270

Synchronous imitation (18 months)

−0.154 −0.102 0.136 −0.110

Mirror self‐recognition (18 months)

0.045 −0.160 0.000 0.024

Note: No correlations were significant after Bonferroni or Benjamini‐Hochberg corrections were applied. Correlation colour scale. −1 1.

T A B L E 2   Spearman correlations between tongue protrusion “imitation” and social cognitive variables

     |  9 of 13REDSHAW Et Al.

As shown in Tables S2 and S5, however, there was no compelling evidence of intra‐individual consistency in these facial model tongue protrusion scores across time points, with no correlations having significant p values using either Bonferroni or Benjamini‐Hochberg (q = 0.05) corrections. Spearman correlation values ranged from −0.126 to 0.230, and a one sample t‐test indicated that the mean correlation size (rs = 0.081, 95% CI [−0.042, 0.203]) did not signifi‐ cantly differ from zero, t (5) = 1.69, p = .151. Furthermore, as shown in Tables S3 and S5, the facial model tongue protrusion scores failed to predict later‐developing social cognitive behaviours in the cur‐ rent sub‐sample of infants, with no correlations having significant p values using either Bonferroni or Benjamini‐Hochberg (q = 0.05) corrections. Spearman correlation values ranged from −0.273 to 0.261, and a one sample t‐test indicated that the mean correlation size (rs = 0.004, 95% CI [−0.041, 0.049]) did not significantly differ from zero, t (31) = 0.17, p = .865. For these mean correlations, the scaled JZS Bayes Factors in favour of the null hypotheses were 1.05 and 5.22, respectively. Our data therefore contain no evidence to suggest inter‐individual reliability in neonates’ propensity to pro‐ trude their tongues in response to facial gestures, and no evidence that scores for such a tendency at any neonatal time point have any predictive value for the later‐developing social cognitive behaviours we measured.

3.4.2 | Associations among later‐developing social cognitive variables

Our second series of post‐hoc analyses examined relationships among the later‐developing social cognitive variables themselves. Similar to our analyses involving the neonatal “imitation” scores, we found no compelling evidence of intra‐individual consistency in these variables. As shown in Tables S4 and S5, no Spearman correla‐ tions had significant p values when either Bonferroni or Benjamini‐ Hochberg (q = 0.05) corrections were applied. Correlation values ranged from −0.282 to 0.349, and a one sample t‐test indicated that the mean correlation size (rs = 0.050, 95% CI [−0.007, 0.107]) did not significantly differ from zero, t (27) = 1.79, p = .084. For this mean correlation, the scaled JZS Bayes Factor in favour of the null hypoth‐ esis was 1.22.

4   |   D I S C U S S I O N

The original aim of our research programme was to examine longi‐ tudinal relationships between neonatal imitation and later‐develop‐ ing social cognitive variables (Suddendorf et al., 2013), yet this aim was abandoned after we failed to obtain any compelling evidence of imitation when participants were neonates (Oostenbroek et al., 2016). Following on from Meltzoff et al.'s (2017) re‐analysis of our data, however, we revisited the possibility of observing such longi‐ tudinal associations. If Meltzoff et al.'s (2017) operationalization of neonatal imitation is valid, and if the like me framework (Meltzoff, 2005, 2007) is correct, then we would expect imitation scores to

predict measures of social cognitive development (Heimann et al., 1989; Simpson, Paukner, et al., 2014b; Suddendorf et al., 2013). This hypothesis was not supported by the results.

Across the four neonatal time points between 1 and 9 weeks, there was no evidence that infants’ tongue protrusion “imitation” scores were positively and reliably correlated with each other. Rather, the average correlation did not significantly differ from zero. Even granting Meltzoff et al.'s (2017) operationalization of imitation, this finding fails to support the hypothesis that there exists a spe‐ cial class of “imitators” among the population of neonates (Heimann, 2002). In defence of this idea, Simpson, Murray, et al. (2014a) write that “only about 50% of neonates consistently engage in imitation of facial gestures” (pp. 7; also see Paukner, Simpson, Ferrari, Mrozek, & Suomi, 2014; Simpson, Paukner, et al., 2014b). We suggest, how‐ ever, that this proportion of 50% is no coincidence. Indeed, if au‐ thors are categorizing infants as “imitators” primarily on the basis that they show greater increases in Action A in response to Modelled Action A than in response to Modelled Action B (see, e.g. studies with rhesus macaques by Simpson, Miller, Ferrari, Suomi, & Paukner, 2016; Simpson, Paukner, Sclafani, Suomi, & Ferrari, 2013; Simpson, Paukner, et al., 2014b; Wooddell, Simpson, Murphy, Dettmer, & Paukner, 2019), then one would expect about 50% of infants to be “imitators” by chance alone (note also that these macaque studies do not report results using appropriate control models; Redshaw, 2019). We suggest that studies should not classify infants as consistent “im‐ itators” unless it can be shown that (a) there is an overall effect of imitation in the sample, and (b) there is a positive correlation be‐ tween imitation scores across time points and actions. Although it is debateable whether the neonates in our sample met criterion (a) for tongue protrusion (cf. Meltzoff et al., 2018, 2017; Oostenbroek et al., 2016, 2018), there can be no doubt that they failed to meet criterion (b).

One might argue that, even given the lack of correlations be‐ tween “imitation” scores across neonatal time points, there may still be predictive value for the scores from one particular time point. Indeed, given that tongue protrusion “imitation” scores in this subsa‐ mple of Oostenbroek et al.'s (2016) neonates were only significantly above zero at 9 weeks, it could be contended that this was the only time point when we were capturing true imitation variance. If so, then the like me framework would only predict “imitation” scores at this time point to significantly correlate with later developing social cognitive variables. Our data fail to support this possibility. There was no evidence that tongue protrusion “imitation” scores at 9 weeks – or at any other time point for that matter – predicted any of the later developing social cognitive variables. Thus, even granting the most charitable interpretation of Meltzoff et al.'s (2017) re‐anal‐ ysis of our data, there is still no evidence for the prevailing like me framework of neonatal imitation's function.

An alternative explanation for the lack of correlations between neonatal imitation and later developing social cognition is that, rather than differing across individuals (Heimann, 2002; Simpson, Murray, et al., 2014a), the capacity is equally available to all typically developing infants. Under this scenario, any individual differences

10 of 13  |     REDSHAW Et Al.

in measured neonatal imitation scores would exist simply as a func‐ tion of fluctuations in motivation and attention during testing – and not social cognitive proficiency. This possibility seems unlikely, how‐ ever, given that previous studies have found reliable intra‐individual stability in neonatal temperament (Wachs, Pollitt, Cueto, & Jacoby, 2004; Worobey & Blajda, 1989). Thus, if measures of neonatal imi‐ tation do indeed capture variance in motivation and attention rather than capacity, then one would still expect to find consistencies in neonatal imitation scores as a function of individual differences in temperament. Our data show no evidence of such consistencies.

Another alternative explanation for the lack of correlations is that neonatal imitation is indeed a genuine phenomenon, and yet, contra Meltzoff's (2005, 2007) like me framework, it has no link at all to later‐developing forms of imitation and social cognition (Bjorklund, 1987). Under this view, one might expect individual dif‐ ferences in neonatal imitation to predict only very early forms of social cognition, such as the tendency to maintain mutual gaze with a caregiver (see Heimann, 1989), and not the forms we measured here. Of course, both of these alternative explanations presuppose that neonatal imitation is a genuine phenomenon, which recent evidence suggests is unlikely (Arcaro et al., 2017; Barbosa, 2017; Cracco et al., 2018; Keven & Akins, 2017; de Klerk et al., 2018; McKyton et al., 2018; Oostenbroek et al., 2016; Redshaw, 2019).

Although our results argue against neonatal imitation as the foundational building block of the like me framework (Meltzoff, 2005, 2007), we do not consider the framework itself to be com‐ pletely untenable. Indeed, human preschoolers tend to faithfully copy many actions modelled to them, even those that are clearly irrelevant to achieving an instrumental outcome (for a recent re‐ view, see Hoehl et al., 2019). Non‐human great apes, on the other hand, typically copy instrumental actions only (Clay & Tennie, 2017; Horner & Whiten, 2005). One plausible mechanism for the develop‐ ment of this uniquely human imitative tendency is that, consistent with the like me framework, children “represent the acts of others and their own acts in commensurate terms” (Meltzoff, 2007, pp. 126). Our data merely diverge from this framework by suggesting that the capacity to recognize and act upon such cross‐modal equiv‐ alences may instead emerge postnatally.

4.1 | Exploratory findings, limitations and future directions

In an exploratory, post‐hoc series of analyses, we found support for Bjorklund's (2018) observation that the neonates in our original sam‐ ple tended to protrude their tongues more frequently in response to facial gesture models than to other models. Bjorklund suggested that such a tendency – while not imitation – might serve to maintain so‐ cial interactions between infants and their caregivers. Several other authors have made similar cases about neonatal actions, with vary‐ ing degrees of richness in their interpretations of behavioural match‐ ing (see Bjorklund, 1987; Byrne, 2005; Heimann, 1989; Jones, 2007, 2009; Legerstee, 1991; Nagy & Molnar, 2004). Although infants ap‐ pear to lack cortical control over tongue movements in the first few

months of life (Keven & Akins, 2017), they may still increase their rates of tongue protrusion as a function of general arousal (Jones, 1996, 2006). Furthermore, parents often imitate their infants’ ac‐ tions (Kokkinaki & Kugiumutzakis, 2000), including tongue protru‐ sion (Jones & Yoshida, 2011), and this tendency appears to predict infants’ own rudimentary signs of imitation at 4 months of age (de Klerk et al., 2018). One possibility, therefore, is that neonatal tongue protrusion does in fact function to increase caregiver bonding and facilitate the eventual development of imitation, and that neonates’ general arousal when observing facial gestures is a mechanism that facilitates this process. This would be consistent with Meltzoff's (2005, 2007) broader point about neonatal behaviours serving a so‐ cial function, although not in the rich intentional sense that the like me framework proposes. Note, however, that we found no significant intra‐individual consistency in neonates’ specific tendency to pro‐ trude their tongue in response to facial gestures. This tendency may therefore fluctuate as a function of general, species‐wide factors that vary over time, rather than as a function of genetically ingrained individual differences. Still, the Bayes Factor for the mean correla‐ tion was close to 1 (i.e., failure to discriminate between the null and alternative hypothesis), and so future research with increased power may indeed uncover significant intra‐individual consistency.

In a second series of post‐hoc analyses, we found that the so‐ cial cognitive measures themselves also failed to correlate with each other across time points. This pattern of results is broadly consistent with those of several other studies that have failed to find reliable correlations among several social cognitive variables in infancy (e.g. Slaughter & McConnell, 2003; Striano & Bertin, 2005; Striano, Stahl, & Cleveland, 2009). The pattern is inconsistent, however, with that of Carpenter et al. (1998), who found several correlations between object‐directed imitation, attention following, and communicative gesture variables in infants aged between 9 and 15 months. It remains ambiguous, therefore, just how much unity exists across the various measures of early social cognitive development (also see Nielsen & Dissanayake, 2004). One possibility is that previous interpretations of these measures have been overly rich (cf. Haith, 1998), and that they simply do not reliably gauge the development of domain‐general so‐ cial cognitive faculties. Again, however, the Bayes Factor for the mean correlation was quite close to 1, meaning that a higher powered study may have indeed uncovered significant effects. Only future research and perhaps meta‐analytic techniques will resolve this issue.

The current study provides the first longitudinal investigation of associations between neonatal “imitation” and later‐developing forms of human social cognition since Heimann et al. (1989) initially called for such an investigation three decades ago. Nevertheless, despite its comprehensiveness and relatively large sample in infant psychology terms, the study may still have been limited by power issues. This limitation, however, must be considered in the light of our overwhelming pattern of null findings, with not a single p value crossing the threshold for statistical significance using either con‐ servative (Bonferroni) or liberal (Benjamini‐Hochberg) corrections. It must also be considered in light of the strong claim at the cen‐ tre of the like me framework – that neonatal imitation is an evolved

     |  11 of 13REDSHAW Et Al.

mechanism functioning as the engine of human social cognition (Meltzoff, 2005, 2007). If this claim is true, then one might expect associations with social cognition to more readily evince themselves, even with sample sizes such as ours.

Other limitations include the fact that our object‐directed im‐ itation tasks did not include a baseline measure, and that some of the actions contributing to scores on these tasks may have instead reflected more basic processes such as stimulus enhancement (e.g. consider the requirement to open a door and touch a target toy in the door task). Although we wished to keep our tasks relatively short given the large assessment protocol, it would have indeed been ideal to have some baseline measure in this particular case. Note, however, that we detected large degrees of variance in all of our social cogni‐ tive measures, including object‐directed imitation (see Figure 3), and that we replicated previous findings showing increases in children's object‐directed imitative fidelity with age (see Figure 2). Presumably, at least some of this variance was due to individual differences and developmental transitions in children's capacity and propensity to copy the actions just shown to them by the experimenter. Therefore, one might still have expected correlations with neonatal “imitation” scores if such associations genuinely exist in the population.

4.2 | Conclusion

In summary, we find no evidence to support a foundational role of neonatal imitation in social cognition (Meltzoff, 2005, 2007). Despite the fact that imitation is critical to human sociality and cumulative culture (Legare & Nielsen, 2015; Whiten, McGuigan, Marshall‐Pescini, & Hopper, 2009), the best available evidence sug‐ gests it is not present at birth (Keven & Akins, 2017; Oostenbroek et al., 2016). And indeed, the current results suggest that even liberal operationalizations of neonatal imitation (Meltzoff et al., 2017) show no intra‐individual consistency across time points and no associa‐ tions with later‐developing social cognitive behaviours. Although we cannot possibly prove absence, our comprehensive set of null results provides the most compelling form of evidence against neonatal imitation and the like me framework yet. Unless convincing contra‐ dictory evidence emerges, developmental psychologists must re‐ evaluate the innate and environmental factors that contribute to the emergence of imitation and more complex social cognitive behaviour (Heyes, 2016b; Jones, 2017; Oostenbroek et al., 2018).

A C K N O W L E D G E M E N T S

This research was funded by an Australian Research Council Discovery Project grant (DP0985969) awarded to VS, MN & TS, and a UQ Development Fellowship (UQFEL1832633) awarded to JR. We sincerely thank the parents and infants who participated, and Jennifer Magerl Fuller for her assistance with reliability coding.

C O N F L I C T O F I N T E R E S T

The authors hereby declare no conflicts of interest.

D ATA AVA I L A B I L I T Y S TAT E M E N T

The data that support the findings of this study are available as on‐ line supplementary material to the article, and on the Open Science Framework at osf.io/s5f2t/ .

O R C I D

Jonathan Redshaw https://orcid.org/0000‐0002‐7729‐1577

Mark Nielsen https://orcid.org/0000‐0002‐0402‐8372

Virginia Slaughter https://orcid.org/0000‐0001‐9315‐1497

Siobhan Kennedy‐Costantini https://orcid. org/0000‐0002‐6935‐1760

Jessica Crimston https://orcid.org/0000‐0003‐2093‐601X

Thomas Suddendorf https://orcid.org/0000‐0003‐3328‐7442

R E F E R E N C E S

Arcaro, M. J., Schade, P. F., Vincent, J. L., Ponce, C. R., & Livingstone, M. S. (2017). Seeing faces is necessary for face‐domain formation. Nature Neuroscience, 20(10), 1404–1412. https ://doi.org/10.1038/nn.4635

Asendorpf, J. B., Warkentin, V., & Baudonniere, P. M. (1996). Self‐aware‐ ness and other‐awareness. II: Mirror self‐recognition, social contin‐ gency awareness, and synchronic imitation. Developmental Psychology, 32(2), 313–321. https ://doi.org/10.1037//0012‐1649.32.2.313

Barbosa, P. G. (2017). Are you like me? Maybe, but I will not imitate you! A longitudinal study on newborns and infants’ imitation and conspe‐ cific identification skills. Doctoral dissertation. University of Alberta.

Behne, T., Liszkowski, U., Carpenter, M., & Tomasello, M. (2012). Twelve‐ month‐olds’ comprehension and production of pointing. British Journal of Developmental Psychology, 30(3), 359–375. https ://doi. org/10.1111/j.2044‐835X.2011.02043.x

Bjorklund, D. F. (1987). A note on neonatal imitation. Developmental Review, 7(1), 86–92. https ://doi.org/10.1016/0273‐2297(87)90006‐2

Bjorklund, D. F. (2018). A metatheory for cognitive development (or “Piaget is dead” revisited). Child Development, 89(6), 2288–2302. https ://doi.org/10.1111/cdev.13019

Boyd, R., & Richerson, P. J. (1996). Why culture is common, but cultural evolution is rare. Proceedings of the British Academy, 88(1), 77–93.

Brass, M., & Heyes, C. (2005). Imitation: Is cognitive neuroscience solving the correspondence problem? Trends in Cognitive Sciences, 9(10), 489– 495. https ://doi.org/10.1016/j.tics.2005.08.007

Byrne, R. W. (2003). Imitation as behaviour parsing. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 358(1431), 529–536. https ://doi.org/10.1098/rstb.2002.1219

Byrne, R. W. (2005). Social cognition: Imitation, imitation, imitation. Current Biology, 15(13), R498–R500. https ://doi.org/10.1016/j. cub.2005.06.031

Carpenter, M., Nagell, K., & Tomasello, M. (1998). Social cognition, joint attention, and communicative competence from 9 to 15 months of age. Monographs of the Society for Research in Child Development, 63(4), 1–174. https ://doi.org/10.2307/1166214

Cheng, C. M., & Chartrand, T. L. (2003). Self‐monitoring without aware‐ ness: Using mimicry as a nonconscious affiliation strategy. Journal of Personality and Social Psychology, 85(6), 1170–1179. https ://doi. org/10.1037/0022‐3514.85.6.1170

Cicchetti, D. V. (1994). Guidelines, criteria, and rules of thumb for evaluating normed and standardized assessment instruments in psychology. Psychological Assessment, 6(4), 284. https ://doi. org/10.1037/1040‐3590.6.4.284

12 of 13  |     REDSHAW Et Al.

Clay, Z., & Tennie, C. (2017). Is overimitation a uniquely human phenom‐ enon? Insights from human children as compared to bonobos. Child Development. 89(5):1535–1544. https ://doi.org/10.1111/cdev.12857

Cook, R., Bird, G., Catmur, C., Press, C., & Heyes, C. (2014). Mirror neu‐ rons: From origin to function. Behavioral and Brain Sciences, 37(2), 177–192. https ://doi.org/10.1017/S0140 525X1 3000903

Corkum, V., & Moore, C. (1998). The origins of joint visual attention in infants. Developmental Psychology, 34(1), 28–38. https ://doi. org/10.1037/0012‐1649.34.1.28

Cracco, E., Bardi, L., Desmet, C., Genschow, O., Rigoni, D., De Coster, L., … Brass, M. (2018). Automatic imitation: A meta‐analysis. Psychological Bulletin, 144(5), 453–500. https ://doi.org/10.1037/bul00 00143

de Klerk, C. C., Lamy‐Yang, I., & Southgate, V. (2018). The role of sensorimo‐ tor experience in the development of mimicry in infancy. Developmental Science, 22(3), e12771. https ://doi.org/10.1111/desc.12771

Ferrari, P. F., Bonini, L., & Fogassi, L. (2009). From monkey mirror neu‐ rons to primate behaviours: Possible ‘direct’ and ‘indirect’ pathways. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1528), 2311–2323. https ://doi.org/10.1098/rstb.2009.0062

Field, T. M., Woodson, R., Greenberg, R., & Cohen, D. (1982). Discrimination and imitation of facial expressions neonates. Science, 218(4568), 179–181. https ://doi.org/10.1126/scien ce.7123230

Gallese, V. (2001). The ‘shared manifold’ hypothesis: From mirror neu‐ rons to empathy. Journal of Consciousness Studies, 8(5–6), 33–50.

Gallup, G. G. (1970). Chimpanzees: Self‐recognition. Science, 167(3914), 86–87. https ://doi.org/10.1126/scien ce.167.3914.86

Haith, M. M. (1998). Who put the cog in infant cognition? Is rich interpre‐ tation too costly? Infant Behavior and Development, 21(2), 167–179. https ://doi.org/10.1016/S0163‐6383(98)90001‐7

Heimann, M. (1989). Neonatal imitation, gaze aversion, and mother‐in‐ fant interaction. Infant Behavior and Development, 12(4), 495–505. https ://doi.org/10.1016/0163‐6383(89)90029‐5

Heimann, M. (2002). Notes on individual differences and the assumed elusiveness of neonatal imitation. In A. N. Meltzoff & W. Prinz (Eds.), The imitative mind: Development, evolution, and brain bases (pp. 74– 84). New York: Cambridge University Press.

Heimann, M., Nelson, K. E., & Schaller, J. (1989). Neonatal imitation of tongue protrusion and mouth opening: Methodological aspects and ev‐ idence of early individual differences. Scandinavian Journal of Psychology, 30(2), 90–101. https ://doi.org/10.1111/j.1467‐9450.1989.tb010 72.x

Henrich, J., & McElreath, R. (2003). The evolution of cultural evolution. Evolutionary Anthropology: Issues, News, and Reviews, 12(3), 123–135. https ://doi.org/10.1002/evan.10110

Heyes, C. (2010). Where do mirror neurons come from? Neuroscience & Biobehavioral Reviews, 34(4), 575–583. https ://doi.org/10.1016/j. neubi orev.2009.11.007

Heyes, C. (2016a). Homo imitans? Seven reasons why imitation couldn't possibly be associative. Philosophical Transactions of the Royal Society B: Biological Sciences, 371(1686), 20150069. https ://doi.org/10.1098/ rstb.2015.0069

Heyes, C. (2016b). Imitation: Not in our genes. Current Biology, 26(10), R412–R414. https ://doi.org/10.1016/j.cub.2016.03.060

Hoehl, S., Keupp, S., Schleihauf, H., McGuigan, N., Buttelmann, D., & Whiten, A. (2019). ‘Over‐imitation’: A review and appraisal of a de‐ cade of research. Developmental Review, 51(1), 90–108. https ://doi. org/10.1016/j.dr.2018.12.002

Horner, V., & Whiten, A. (2005). Causal knowledge and imitation/emula‐ tion switching in chimpanzees (Pan troglodytes) and children (Homo sapiens). Animal Cognition, 8(3), 164–181. https ://doi.org/10.1007/ s10071‐004‐0239‐6

Iacobini, M. (2009). Imitation, empathy, and mirror neurons. Annual Review of Psychology, 60, 653–670. https ://doi.org/10.1146/annur ev.psych.60.110707.163604

Johnson, S., Slaughter, V., & Carey, S. (1998). Whose gaze will infants fol‐ low? The elicitation of gaze‐following in 12‐month‐olds. Developmental Science, 1(2), 233–238. https ://doi.org/10.1111/1467‐7687.00036

Jones, S. S. (1996). Imitation or exploration? Young infants' matching of adults' oral gestures. Child Development, 67(5), 1952–1969. https :// doi.org/10.2307/1131603

Jones, S. S. (2006). Exploration or imitation? The effect of music on 4‐ week‐old infants’ tongue protrusions. Infant Behavior and Development, 29(1), 126–130. https ://doi.org/10.1016/j.infbeh.2005.08.004

Jones, S. S. (2007). Imitation in infancy: The development of mimicry. Psychological Science, 18(7), 593–599. https ://doi. org/10.1111/j.1467‐9280.2007.01945.x

Jones, S. S. (2009). The development of imitation in infancy. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1528), 2325–2335. https ://doi.org/10.1098/rstb.2009.0045

Jones, S. S. (2017). Can newborn infants imitate? Wiley Interdisciplinary Reviews: Cognitive Science, 8(1–2), e1410. https ://doi.org/10.1002/ wcs.1410

Jones, S. S., & Yoshida, H. (2011). Imitation in infancy and the acquisi‐ tion of body knowledge. In V. Slaughter & C. A. Brownell (Eds.), Early development of body representations (pp. 207–225). Cambridge, UK: Cambridge University Press.

Keven, N., & Akins, K. A. (2017). Neonatal imitation in context: Sensorimotor development in the perinatal period. Behavioral and Brain Sciences, 40, e381. https ://doi.org/10.1017/S0140 525X1 6000911

Kokkinaki, T., & Kugiumutzakis, G. (2000). Basic aspects of vocal imita‐ tion in infant‐parent interaction during the first 6 months. Journal of Reproductive and Infant Psychology, 18(3), 173–187. https ://doi. org/10.1080/71368 3042

Lakin, J. L., Jefferis, V. E., Cheng, C. M., & Chartrand, T. L. (2003). The cha‐ meleon effect as social glue: Evidence for the evolutionary significance of nonconscious mimicry. Journal of Nonverbal Behavior, 27(3), 145–162.

Legare, C. H., & Nielsen, M. (2015). Imitation and innovation: The dual engines of cultural learning. Trends in Cognitive Sciences, 19(11), 688– 699. https ://doi.org/10.1016/j.tics.2015.08.005

Legerstee, M. (1991). The role of person and object in eliciting early imi‐ tation. Journal of Experimental Child Psychology, 51(3), 423–433. https ://doi.org/10.1016/0022‐0965(91)90086‐8

McKyton, A., Ben‐Zion, I., & Zohary, E. (2018). Lack of automatic imita‐ tion in newly sighted individuals. Psychological Science, 29(2), 304– 310. https ://doi.org/10.1177/09567 97617 731755

Meltzoff, A. N. (1996). The human infant as an imitative generalist: A 20‐ year progress report on infant imitation with implications for com‐ parative psychology. In C. M. Heyes & B. G. Galef (Eds.), Social learn‐ ing in animals: The roots of culture (pp. 55–77). New York: Academic Press.

Meltzoff, A. N. (2005). Imitation and other minds: The ‘like me’ hypoth‐ esis. In S. Hurley & N. Chater (Eds.), Perspectives on imitation: From neuroscience to social science (Vol. 2: Imitation, human development, and culture, pp. 55–77). Cambridge, MA: MIT Press.

Meltzoff, A. N. (2007). ‘Like me’: A foundation for social cog‐ nition. Developmental Science, 10(1), 126–134. https ://doi. org/10.1111/j.1467‐7687.2007.00574.x

Meltzoff, A. N., & Brooks, R. (2001). “Like me” as a building block for understanding other minds: Bodily acts, attention, and intention. In B. F. Malle, L. J. Moses & D. A. Baldwin (Eds.), Intentions and intention‐ ality: Foundations of social cognition (pp. 171–192). Cambridge, MA: MIT Press.

Meltzoff, A. N., & Decety, J. (2003). What imitation tells us about social cognition: A rapprochement between developmental psychology and cognitive neuroscience. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 358(1431), 491–500. https :// doi.org/10.1098/rstb.2002.1261

Meltzoff, A. N., & Moore, M. K. (1977). Imitation of facial and manual gestures by human neonates. Science, 198(4312), 75–78.

Meltzoff, A. N., & Moore, M. K. (1992). Early imitation within a functional framework: The importance of person identity, movement, and de‐ velopment. Infant Behavior & Development, 15(4), 479–505. https :// doi.org/10.1016/0163‐6383(92)80015‐M

     |  13 of 13REDSHAW Et Al.

Meltzoff, A. N., Murray, L., Simpson, E., Heimann, M., Nagy, E., Nadel, J., … Subiaul, F. (2018). Eliciting imitation in early infancy. Developmental Science, 22(2), e12738. https ://doi.org/10.1111/desc.12738

Meltzoff, A. N., Murray, L., Simpson, E., Heimann, M., Nagy, E., Nadel, J., Subiaul, F. (2017). Re‐examination of Oostenbroek et al. (2016): Evidence for neonatal imitation of tongue protrusion. Developmental Science, 21(4), e12609. https ://doi.org/10.1111/desc.12609

Moore, R. (2013). Imitation and conventional communication. Biology & Philosophy, 28(3), 481–500. https ://doi.org/10.1007/s10539‐012‐9349‐8

Mundy, P., Block, J., Delgado, C., Pomares, Y., Van Hecke, A. V., & Parlade, M. V. (2007). Individual differences and the development of joint at‐ tention in infancy. Child Development, 78(3), 938–954. https ://doi. org/10.1111/j.1467‐8624.2007.01042.x

Nadel, J., & Butterworth, G. (1999). Imitation in infancy. Cambridge, NY: Cambridge University Press.

Nagy, E., & Molnar, P. (2004). Homo imitans or homo provocans? Human im‐ printing model of neonatal imitation. Infant Behavior and Development, 27(1), 54–63. https ://doi.org/10.1016/j.infbeh.2003.06.004

Nielsen, M. (2006). Copying actions and copying outcomes: Social learn‐ ing through the second year. Developmental Psychology, 42(3), 555. https ://doi.org/10.1037/0012‐1649.42.3.555

Nielsen, M., & Dissanayake, C. (2004). Pretend play, mirror self‐recogni‐ tion and imitation: A longitudinal investigation through the second year. Infant Behavior and Development, 27(3), 342–365. https ://doi. org/10.1016/j.infbeh.2003.12.006

Oostenbroek, J., Redshaw, J., Davis, J., Kennedy‐Costantini, S., Nielsen, M., Slaughter, V., & Suddendorf, T. (2018). Re‐evaluating the neonatal imitation hypothesis. Developmental Science, 22(2), e12720. https :// doi.org/10.1111/desc.12720

Oostenbroek, J., Suddendorf, T., Nielsen, M., Redshaw, J., Kennedy‐ Costantini, S., Davis, J., … Slaughter, V. (2016). Comprehensive lon‐ gitudinal study challenges the existence of neonatal imitation in hu‐ mans. Current Biology, 26(10), 1334–1338. https ://doi.org/10.1016/j. cub.2016.03.047

Paukner, A., Pedersen, E. J., & Simpson, E. A. (2017). Testing the arousal hypothesis of neonatal imitation in infant rhesus macaques. PLoS ONE, 12(6), e0178864.https ://doi.org/10.1371/journ al.pone.0178864

Paukner, A., Simpson, E. A., Ferrari, P. F., Mrozek, T., & Suomi, S. J. (2014). Neonatal imitation predicts how infants engage with faces. Developmental Science, 17(6), 833–840. https ://doi.org/10.1111/desc.12207

Paulus, M. (2011). Imitation in infancy: Conceptual considerations. Theory & Psychology, 21(6), 849–856. https ://doi.org/10.1177/09593 54310 395990

Paulus, M., Hunnius, S., Vissers, M., & Bekkering, H. (2011). Imitation in infancy: Rational or motor resonance? Child Development, 82(4), 1047–1057. https ://doi.org/10.1111/j.1467‐8624.2011.01610.x

Piaget, J. (1962). Play, dreams and imitation in childhood. New York: Norton.

Ray, E., & Heyes, C. (2011). Imitation in infancy: The wealth of the stimulus. Developmental Science, 14(1), 92–105. https ://doi. org/10.1111/j.1467‐7687.2010.00961.x

Redshaw, J. (2019). Re‐analysis of data reveals no evidence for neonatal imitation in rhesus macaques. Biology Letters, 15(7), 20190342. https ://doi.org/10.1098/rsbl.2019.0342

Simpson, E. A., Miller, G. M., Ferrari, P. F., Suomi, S. J., & Paukner, A. (2016). Neonatal imitation and early social experience predict gaze following abilities in infant monkeys. Scientific Reports, 6, 20233. https ://doi.org/10.1038/srep2 0233

Simpson, E. A., Murray, L., Paukner, A., & Ferrari, P. F. (2014a). The mir‐ ror neuron system as revealed through neonatal imitation: Presence from birth, predictive power and evidence of plasticity. Philosophical Transactions of the Royal Society, B, Biological Sciences, 369, 20130289. https ://doi.org/10.1098/rstb.2013.0289

Simpson, E. A., Paukner, A., Sclafani, V., Suomi, S. J., & Ferrari, P. F. (2013). Lipsmacking imitation skill in newborn macaques is predictive of

social partner discrimination. PLoS ONE, 8(12), e82921. https ://doi. org/10.1371/journ al.pone.0082921

Simpson, E. A., Paukner, A., Suomi, S. J., & Ferrari, P. F. (2014b). Visual attention during neonatal imitation in newborn macaque mon‐ keys. Developmental Psychobiology, 56(4), 864–870. https ://doi. org/10.1002/dev.21146

Slaughter, V., & McConnell, D. (2003). Emergence of joint attention: Relationships between gaze following, social referencing, imitation, and naming in infancy. The Journal of Genetic Psychology, 164(1), 54– 71. https ://doi.org/10.1080/00221 32030 9597503

Striano, T., & Bertin, E. (2005). Social‐cognitive skills between 5 and 10 months of age. British Journal of Developmental Psychology, 23(4), 559–568. https ://doi.org/10.1348/02615 1005X 26282

Striano, T., Stahl, D., & Cleveland, A. (2009). Taking a closer look at social and cognitive skills: A weekly longitudinal assessment between 7 and 10 months of age. European Journal of Developmental Psychology, 6(5), 567–591. https ://doi.org/10.1080/17405 62070 1480642

Suddendorf, T., & Butler, D. L. (2013). The nature of visual self‐recog‐ nition. Trends in Cognitive Sciences, 17(3), 121–127. https ://doi. org/10.1016/j.tics.2013.01.004

Suddendorf, T., Oostenbroek, J., Nielsen, M., & Slaughter, V. P. (2013). Is newborn imitation developmentally homologous to later social‐cog‐ nitive developments? Developmental Psychobiology, 55, 52–58. https ://doi.org/10.1002/dev.21005

Tomasello, M., Kruger, A. C., & Ratner, H. H. (1993). Cultural learn‐ ing. Behavioral and Brain Sciences, 16(3), 495–552. https ://doi. org/10.1017/S0140 525X0 003123X

Trevarthen, C., & Aitken, K. J. (2001). Infant intersubjectiv‐ ity: Research, theory, and clinical applications. The Journal of Child Psychology and Psychiatry, 42(1), 3–48.https ://doi. org/10.1111/1469‐7610.00701

Uzgiris, I. C., & Hunt, J. M. (1975). Assessment in infancy: Ordinal scales of psychological development. Urbana, IL: University of Illinois Press.

Wachs, T. D., Pollitt, E., Cueto, S., & Jacoby, E. (2004). Structure and cross‐contextual stability of neonatal temperament. Infant Behavior and Development, 27(3), 382–396. https ://doi.org/10.1016/j. infbeh.2004.02.001

Whiten, A., McGuigan, N., Marshall‐Pescini, S., & Hopper, L. M. (2009). Emulation, imitation, over‐imitation and the scope of culture for child and chimpanzee. Philosophical Transactions of the Royal Society of London B: Biological Sciences, 364(1528), 2417–2428. https ://doi. org/10.1098/rstb.2009.0069

Wooddell, L. J., Simpson, E. A., Murphy, A. M., Dettmer, A. M., & Paukner, A. (2019). Interindividual differences in neonatal sociality and emotion‐ ality predict juvenile social status in rhesus monkeys. Developmental Science, 22(2), e12749. https ://doi.org/10.1111/desc.12749

Worobey, J., & Blajda, V. M. (1989). Temperament ratings at 2 weeks, 2 months, and 1 year: Differential stablity of activity and emo‐ tionality. Developmental Psychology, 25(2), 257–263. https ://doi. org/10.1037/0012‐1649.25.2.257

S U P P O R T I N G I N F O R M AT I O N

Additional supporting information may be found online in the Supporting Information section at the end of the article. 

How to cite this article: Redshaw J, Nielsen M, Slaughter V, et al. Individual differences in neonatal “imitation” fail to predict early social cognitive behaviour. Dev Sci. 2019;00:e12892. https ://doi.org/10.1111/desc.12892