To be, or not to be, Ay there's the point. –William Shake-speare, The Tragicall Historie of Hamlet, Prince of Denmarke (Reference Shake-speare1603)
More detailed investigation of many phenomena in human behaviour often reveal a variety of mechanisms to be involved. This paper provides a helpful overview of the conflicting literature on the neonatal imitation of tongue protrusion-retraction and a scholarly summary of much of the related neuroscience. With the focus primarily on oropharyngeal movements, I propose that the ontogeny of orofacial central pattern generators for suckling provides a sufficient explanation for this phenomenon. I take the view that the ontogeny provides a unitary explanation and support for the argument focussed on this small component of the repertoire of behaviours observed in caregiver-infant dyads.
Keven & Akins (K&A) state that “orofacial stereotypies are crucial to the maturation of aerodigestion in the neonatal period but also unlikely to co-occur with imitative behavior” (target article abstract). I accept that these movements are central to achieving the process of suckling and its nutritional end, but would suggest that because this is necessary, it is not necessarily a sufficient explanation. Their view reminded me of Polani and MacKeith's statement that “The newborn infant may be described as a tonic animal with oropharyngeal automatisms and neurovegetative mechanisms” (Polani & MacKeith Reference Polani, MacKeith, André-Thomas and Dargassies1960).
The newborn infant is typically alert, interested, and socially responsive in the early hours after birth. Physically neotenous, and helpless without adult assistance to access nutrition, warmth, and care, engaging a responsive adult caregiver is critical to its survival. This physical helplessness is associated with a lengthier period of postnatal brain growth than is seen in any other primate (see Coqueugniot et al. Reference Coqueugniot, Hublin, Veillon, Houet and Jacob2004; de Graaf-Peters & Hadders-Algra Reference de Graaf-Peters and Hadders-Algra2006), with rapid apoptosis and fine-tuning of the systems required for survival based on experience.
K&A state, moreover, that “If NI [neonatal imitation] promotes infant survival we should see the same behaviours in other nonhuman primates with similar social structure, state of maturation at birth, and communicative gestures” (sect. 2, para. 5). I would accept that such evidence is limited. This evidence is limited in part, however, because of the unique extent of our postnatal brain growth, and in part because of the limitations possible on such extrapolations (Clancy et al. Reference Clancy, Finlay, Darlington and Anand2007).
Newborn infants have learnt to recognise their mothers (Hepper Reference Hepper2015). They recognise her vocal characteristics (timbre, prosody, pitch); the timing of her reactions to others; her movement patterns, breathing, and heartbeat (see Ullal-Gupta et al. Reference Ullal-Gupta, der Nederlanden, Christina, Tichko, Lahav and Hannon2013; Webb et al. Reference Webb, Heller, Benson and Lahav2015). Her amniotic fluid is recognised by smell (Schaal et al. Reference Schaal, Marlier and Soussignan1998) as is her dietary intake (Schaal et al. Reference Schaal, Marlier and Soussignan2000). Olfactory-gustatory processes are part of social responsivity. Birth itself contributes to the development of suckling (see Alberts & Ronca Reference Alberts and Ronca2012). The infant's behaviour and responsivity takes place within the context of a rich multisensory social environment and is effected by early experiences. I take issue with the view that developmental psychology accounts of imitation support an extreme form of nativism.
Rather than a crudely simplistic ethological model of specific characteristics as fixed factors eliciting parental responses, successful navigation of the process of early development requires a finely attuned reciprocal process of interaction that we have called intersubjectivity (see Feldman Reference Feldman2015; Trevarthen & Aitken Reference Trevarthen and Aitken2001). Neonatal behaviour is not fixed but adjusts to elicit positive responses from carers (see Adamson et al. Reference Adamson, Als, Tronick and Brazelton1977). These factors are part of a complex pattern of interaction between infant and caregivers that evolves and is fine tuned by both caregiver and infant, enabling human survival.
A number of other behaviours seen in infancy have been subjected to similar scrutiny. Neonatal smiling, for example, was often discounted as “wind” and only interpreted as social by many researchers after the demonstration by Harriet Oster (Reference Oster, Ekman and Rosenberg1997) that social and nonsocial smiling could be clearly discriminated with the facial action coding system showing that, as well as getting wind, babies could really smile.
We are currently seeing the development of second-person neuroscience and the technologies to enable dyadic neuroimaging and explore the interactive basis to human communication (Grossman Reference Grossman2015; Schilbach Reference Schilbach2015; Schilbach et al. Reference Schilbach, Timmermans, Reddy, Costall, Bente, Schlicht and Vogeley2013). This approach is being applied to other poorly understood social situations such as autistic spectrum disorders (see Rolison et al. Reference Rolison, Naples and McPartland2015).
The species homo sapiens is at the extreme on various evolutionary continua. Our neonatal ability to elicit care is highly developed. It seems to be the altricial state of our nonverbal communication that has enabled us to evolve so rapidly by ensuring that human infants have the capacity to both survive and to adapt to vastly different cultural and linguistic milieu.
Clearly, the phenomena which constitute neonatal imitation are overdetermined, and the aspects focused on by K&A do occur at an increased basal frequency in the early weeks as the infant develops the orofacial neuromuscular systems involved in feeding and coordinating this development with pandiculation. This increased early baseline prevalence is also true of the wider range of imitative behaviours (such as finger movements and lip pursing) seen in infancy and involved in many of the studies under discussion.
Confining the discussion to a frame of reference, in which an explanation is sought for tongue protrusion-retraction alone, is overly partisan and fails to embrace or account for the more general aspects of early behavioural synonymy. Although it fits within the authors' explanation of the development of orobuccofacial patterns involved in suckling, it fails to negate the parallel functions in interaction and the evolutionary survival pressures on development.
Changes to prevalence and capacity to perform different actions through early life, described in much of the Piagetian literature on development (Heimann & Plooij Reference Heimann and Plooij2003) have failed to be appreciated in much of the literature on infant imitation (see, for example, Oostenbroek et al. Reference Oostenbroek, Suddendorf, Nielsen, Redshaw, Kennedy-Costantini, Davis, Clark and Slaughter2016), and rarely adjust for background changes with age and development. I accept the point that Esther Thelen's meticulous work led to a revision in our understanding of stepping; however, I would suggest this has limited salience in discussing tongue protrusion.
It takes two to know one.–Gregory Bateson, “Old Men Ought to be Explorers” (in Nachmanovitch Reference Nachmanovitch1982)
To be, or not to be, Ay there's the point. –William Shake-speare, The Tragicall Historie of Hamlet, Prince of Denmarke (Reference Shake-speare1603)
More detailed investigation of many phenomena in human behaviour often reveal a variety of mechanisms to be involved. This paper provides a helpful overview of the conflicting literature on the neonatal imitation of tongue protrusion-retraction and a scholarly summary of much of the related neuroscience. With the focus primarily on oropharyngeal movements, I propose that the ontogeny of orofacial central pattern generators for suckling provides a sufficient explanation for this phenomenon. I take the view that the ontogeny provides a unitary explanation and support for the argument focussed on this small component of the repertoire of behaviours observed in caregiver-infant dyads.
Keven & Akins (K&A) state that “orofacial stereotypies are crucial to the maturation of aerodigestion in the neonatal period but also unlikely to co-occur with imitative behavior” (target article abstract). I accept that these movements are central to achieving the process of suckling and its nutritional end, but would suggest that because this is necessary, it is not necessarily a sufficient explanation. Their view reminded me of Polani and MacKeith's statement that “The newborn infant may be described as a tonic animal with oropharyngeal automatisms and neurovegetative mechanisms” (Polani & MacKeith Reference Polani, MacKeith, André-Thomas and Dargassies1960).
The newborn infant is typically alert, interested, and socially responsive in the early hours after birth. Physically neotenous, and helpless without adult assistance to access nutrition, warmth, and care, engaging a responsive adult caregiver is critical to its survival. This physical helplessness is associated with a lengthier period of postnatal brain growth than is seen in any other primate (see Coqueugniot et al. Reference Coqueugniot, Hublin, Veillon, Houet and Jacob2004; de Graaf-Peters & Hadders-Algra Reference de Graaf-Peters and Hadders-Algra2006), with rapid apoptosis and fine-tuning of the systems required for survival based on experience.
K&A state, moreover, that “If NI [neonatal imitation] promotes infant survival we should see the same behaviours in other nonhuman primates with similar social structure, state of maturation at birth, and communicative gestures” (sect. 2, para. 5). I would accept that such evidence is limited. This evidence is limited in part, however, because of the unique extent of our postnatal brain growth, and in part because of the limitations possible on such extrapolations (Clancy et al. Reference Clancy, Finlay, Darlington and Anand2007).
Newborn infants have learnt to recognise their mothers (Hepper Reference Hepper2015). They recognise her vocal characteristics (timbre, prosody, pitch); the timing of her reactions to others; her movement patterns, breathing, and heartbeat (see Ullal-Gupta et al. Reference Ullal-Gupta, der Nederlanden, Christina, Tichko, Lahav and Hannon2013; Webb et al. Reference Webb, Heller, Benson and Lahav2015). Her amniotic fluid is recognised by smell (Schaal et al. Reference Schaal, Marlier and Soussignan1998) as is her dietary intake (Schaal et al. Reference Schaal, Marlier and Soussignan2000). Olfactory-gustatory processes are part of social responsivity. Birth itself contributes to the development of suckling (see Alberts & Ronca Reference Alberts and Ronca2012). The infant's behaviour and responsivity takes place within the context of a rich multisensory social environment and is effected by early experiences. I take issue with the view that developmental psychology accounts of imitation support an extreme form of nativism.
Rather than a crudely simplistic ethological model of specific characteristics as fixed factors eliciting parental responses, successful navigation of the process of early development requires a finely attuned reciprocal process of interaction that we have called intersubjectivity (see Feldman Reference Feldman2015; Trevarthen & Aitken Reference Trevarthen and Aitken2001). Neonatal behaviour is not fixed but adjusts to elicit positive responses from carers (see Adamson et al. Reference Adamson, Als, Tronick and Brazelton1977). These factors are part of a complex pattern of interaction between infant and caregivers that evolves and is fine tuned by both caregiver and infant, enabling human survival.
A number of other behaviours seen in infancy have been subjected to similar scrutiny. Neonatal smiling, for example, was often discounted as “wind” and only interpreted as social by many researchers after the demonstration by Harriet Oster (Reference Oster, Ekman and Rosenberg1997) that social and nonsocial smiling could be clearly discriminated with the facial action coding system showing that, as well as getting wind, babies could really smile.
We are currently seeing the development of second-person neuroscience and the technologies to enable dyadic neuroimaging and explore the interactive basis to human communication (Grossman Reference Grossman2015; Schilbach Reference Schilbach2015; Schilbach et al. Reference Schilbach, Timmermans, Reddy, Costall, Bente, Schlicht and Vogeley2013). This approach is being applied to other poorly understood social situations such as autistic spectrum disorders (see Rolison et al. Reference Rolison, Naples and McPartland2015).
The species homo sapiens is at the extreme on various evolutionary continua. Our neonatal ability to elicit care is highly developed. It seems to be the altricial state of our nonverbal communication that has enabled us to evolve so rapidly by ensuring that human infants have the capacity to both survive and to adapt to vastly different cultural and linguistic milieu.
Clearly, the phenomena which constitute neonatal imitation are overdetermined, and the aspects focused on by K&A do occur at an increased basal frequency in the early weeks as the infant develops the orofacial neuromuscular systems involved in feeding and coordinating this development with pandiculation. This increased early baseline prevalence is also true of the wider range of imitative behaviours (such as finger movements and lip pursing) seen in infancy and involved in many of the studies under discussion.
Confining the discussion to a frame of reference, in which an explanation is sought for tongue protrusion-retraction alone, is overly partisan and fails to embrace or account for the more general aspects of early behavioural synonymy. Although it fits within the authors' explanation of the development of orobuccofacial patterns involved in suckling, it fails to negate the parallel functions in interaction and the evolutionary survival pressures on development.
Changes to prevalence and capacity to perform different actions through early life, described in much of the Piagetian literature on development (Heimann & Plooij Reference Heimann and Plooij2003) have failed to be appreciated in much of the literature on infant imitation (see, for example, Oostenbroek et al. Reference Oostenbroek, Suddendorf, Nielsen, Redshaw, Kennedy-Costantini, Davis, Clark and Slaughter2016), and rarely adjust for background changes with age and development. I accept the point that Esther Thelen's meticulous work led to a revision in our understanding of stepping; however, I would suggest this has limited salience in discussing tongue protrusion.