Humans exhibit many individual differences when it comes to establishing and maintaining social relationships. These differences can drastically impact an individual's psychological well-being (cite). Being able to detect such differences at an early age could pave the way for earlier interventions and treatment plans than those currently in place (cite). Sensitivity to social cues could in turn have ramifications for an infant's cognitive, social, and emotional development (Feldman, 2007). The concept of neonatal imitation, an infant's ability to match actions within their first four-weeks of life, has been a heated topic for over thirty-five years (39) (cite). An infant's knack to imitate is a vital learning process to aid children in acquiring a certain behavior. Mirroring behaviors such as mouth opening (MO) or tongue protrusion (TP) are early social interactions that may promote social bonding between a mother and infant, support intersubjective interactions, and provide opportunities for infants to learn about social communication norms (Paukner, 2014). Although infants imitate many different things, MO and TP are the most replicated actions (cite). This imitative phenomenon occurs during a period in which infant humans develop new social abilities, such as spontaneously vocalizing or smiling at others. The ability to be socially engaged within the first 4-weeks of life, imitating factors such as MO and TP, is an interrelated factor with cognitive skills as age progresses (cite). It is important to explore this correlation as infants as it is rare to find a newborn behavior that indicates later social behavior. Children with Autism Spectrum Disorder (ASD) tend to have a limitation in cognitive functioning (45; 46) and early mediations can be implemented if indicators are present within an infant's first few weeks of life.
Imitation is a copiously yet dispersed topic due its multidisciplinary origins (35). As previously noted, neonatal imitation is an infant's ability to match a model's specific action more than when presented with a control action within their first four-weeks of life (36). The most important concept of neonatal imitation, making it an important topic to research, is the relationship to atypical neurodevelopmental patterns as the child grows older. Research has shown that roughly 50% of both Nonhuman Primates (NHP), particularly macaque monkeys, and humans imitate (51; 36; 35; 52; Ferrari et al., 2009b; 53). Although there is not much research in humans, in macaque monkeys it has been shown that neonatal imitation predicts both social interest and social skills (Capitanio, 1999, 2002; Capitanio et al., 2008; Dettmer et al., 2016; Ferrari et al., 2009a; Feczko et al., 2016; Machado et al., 2015; Sclafani et al., 2016; Simpson et al., 2016b). Monkeys who exhibit neonatal imitation are found to be more attentive at 1-week-of-age compared to non-imitators and in turn tended to look to faces at 2-4 weeks of age (39; 44). Talk about why monkeys do everything earlier (2-4 weeks compared to 2-months). Nonhuman primates (NHP) and humans are phylogenetically close and have similar neonatal imitation developmental patterns to NHP (50; 42 or 43) and possible underling mechanisms (41; 48; 39; 49). With that being said, the present NHP studies bring about the argument if there are parallels in human infants-whether or not humans are capable of neonatal imitation and if it corresponds to social ability later on in life.
Infant Monkey Studies
Monkey Studies
-Why rhesus monkeys are relevant
-Studies on rhesus monkeys
First monkey study was in 2007 by Pierre
" Found differences in their motor development í reaching, grasping movement
" Define imitation in the first paragraph
" Individual differences in terms of monkeys
-then say there is this one study; this will compare primates to humans so it will make sense to see this parallel & that it's not crazy we do things that monkeys do – create the parallel between monkeys and humans
In 2014, a study on rhesus macaque monkeys demonstrated that neonatal imitation performance may be an early measure of social attention biases and might potentially facilitate the identification of infants at risk for atypical social development (Paukner et al., 2014). Macaque infants were first assessed for neonatal imitation of lip-smacking and TP movement in the first week of life. Macaques engage in neonatal imitation during mother-infant interactions (Ferrari et al., 2009a) and, similar to human infants, about 50% of macaques perform poorly on neonatal imitation tests (Paukner, Ferrari & Suomi, 2011). In ordr to analyze how imitators and non-imitators process faces, the macaques were examined between the 10-28 days using eye tracking technology to measure the number of fixations and duration of fixations to the overall face, but more specifically the eye and mouth areas of the avatar. Paukner found that an individual's social and communicative abilities, even very early in life, appear to be related to a visual preference for the eye area in a neutral Still Face.
Shortly after birth and throughout the first months of life, rhesus macaques (Macaca mulatta) have superior visual acuity compared to humans (Ordy, Latanick, Samorajski, & Massopust, 1964). Rhesus macaque mother-infant pairs often gaze at each other's eyes, intently and intimately, during the first month of infants' lives (Ferrari, Paukner, Ionica & Suomi, 2009a). These interactions often lead to the mother grooming the infant, either with her hands or her mouth (Ferarri et al., 2009a). All of these factors make NHP an excellent model for investigating the basic mechanisms early in life that underlie the emergence of social and cognitive skills.
Infant Human Studies
In 1989, Mikael Heimann demonstrated that, much like monkeys, roughly 50% of infants imitate and 50% do not. This study was a hallmark in neonatal history within humans as it was the first and last study to relay what was found in NHP and find significant results human infants. It was shown that babies who were neonatal imitators, compared to non-imitators, exhibited fewer looks away during face-to-face interaction with their mothers at 3-months of age. Heimann recognized the implications of neonatal imitation and that early cognitive abilities make the infant "socially attuned." When this study was conducted, however, the relationship between neonatal imitation and the infants' behavior while interacting face-to-face with their mother was shown to exist, yet it was difficult to foresee the particular relations one would expect.
AIM & Mirror Motor Neurons Hypotheses
Several hypotheses have been put forward to identify which mechanisms might underlie neonatal imitation. One of them, originally proposed for human neonatal imitation, claims that an active intermodal matching (AIM) hypothesis is responsible. According to this model, proposed by Meltzoff and Moore (1992, 1994), the perception and production of acts in human neonates can be represented within a common supramodal framework, enabling neonates to process visual and motor information cross-modally and subsequently perform the matching motor response. According to their argument, this 'like-me' mechanism allows neonates to automatically engage in social interactions and serve as a scaffold for understanding the international actions of others. Their view has come to be favored by many developmental psychologists, as it places neonatal imitation at the heart of social development.
" We know it's not a reflex because…. Give reference
" We know it's not arousal because…. Give reference
Imitation or something similar?
Many researchers have claimed that the phenomenon of neonatal imitation is described by a simple reflex (Abravanel & Sigafoods, 1984; Anisfeld, 1996; Jacobson, 1979). This view suggests that there is a high probability of an involuntary, reflexive triggering of a particular motor response. Ansifeld (1991, 1996) claimed that this imitative effect was not a flexible social behavior as Meltzoff and Moore (1997, 1983) described it. However, in Meltzoff and Moore's 19__ experiment, when the model opened their mouth, the infants responded with the same gesture, not by sticking their tongue out. In comparison, when the model stuck their tongue out, the infants stuck their tongue out. In addition, when the infant had a pacifier in their mouths while the experimenter stuck their tongue out, the infant still imitated the model after it was taken out a short while later.
Visual Following Patterns
Infant monkeys who imitate within their first week of life, compared to those who do not, spend more time looking to faces and especially the eye region at 2-4 weeks of age (Paukner et al., 2014). In human infants, babies who were neonatal imitators, compared to non-imitators exhibited fewer looks away during face-to-face interactions with their mothers at 3-months of age (Heimann, 1989). Although no recent studies have translated the results found in macaque monkeys to human infants, research does show that newborn infants, even around 9 minutes in age, turn their eyes and heads to follow a series of moving stimuli, mainly to face patterns rather than scrambled or blank stimuli. This is important because it negates the concern that arises regarded a newborns visual system. Research has shown that limitations in an infant's optical system could result in them not being able to adequately see the behavioral gestures of a model, let alone imitate them. However, in 1992, Hainline and Abramov argued that the newborn's visual system is mature enough to function efficiently in the first few weeks of life, and research demonstrated that infants may have an innate preference for faces and can visually track a face-like stimulus when only a few minutes old.
Plan of Action
More than 30 years of research on neonatal imitation has still not resolved questions about whether the phenomenon exists, how prevalent it is, and what it means. If neonatal imitation exists, it is possible that newborns have an innate capacity for communication and can be an early indicator for later social deficits. All of these reasons are why the continuation of this neonatal imitation's relationship to social ability later in life is key. A primary issue in neonatal imitation studies lie in lack of longitudinal data. A vast majority of studies have only tested newborns on a single occasion. Our study proposes a longitudinal approach to address this problem and ensure that testing is done when infants are in a suitable state. Infants are recruited through local events. For the current study, human infants were first assessed for neonatal imitation of mouth opening and tongue protrusion movements twice in the first four-weeks of life. Babies imitate many different stimuli, but MO and TP gestures are the most well replicated actions. To analyze how imitators and non-imitators process faces, we showed a video of a smiling girl. Using eye-tracking technology, we presented the smiling-video to the infants at 2-months of age and measured the number of fixations and duration of fixations to the overall face, but more specifically to the eye and mouth areas (Figure). Why 2 months of age. Based on Heimann et al.'s (1989) and Paukner, et al.'s (2014) finding that neonatal imitation performance predicts gaze aversion in human infants, we hypothesized that human infants who imitate mouth movement in the first four weeks of life would show increased scanning of the eye region (rather than the mouth region) when 2-months old. We further aimed to examine whether the type of movement infants imitated (tongue protrusion or mouth opening) made them particularly sensitive to the eye region when that movement (rather than a still face) was displayed.