Index Finger Movement Imitation by Human Neonates: Motivation, Learning, and Left-Hand Preference

Abstract

Imitation of a fine motor movement, index finger protrusion, was examined in 39 neonates using an ethologically based objective coding system. Results confirmed that imitation of finger movements exists, and infants demonstrated "learning" as imitation developed through an incomplete imitation stage. Neonatal imitation was more frequently left-handed, an early sign of laterality in motivation to be investigated further. The existence of index finger imitation in human neonates indicates that volitional control of individuated finger movements develops much earlier than previously thought. The differential increase of index finger protrusion movements during the imitation periods suggests that this behavior is not an automatic response triggered by general arousal but instead is a true indicator of purposeful neonatal imitation. The cognitive developmental approach in the first half of the 20th century (1) assumed that imitation of observed actions occurs at the earliest from 10 -12 mo of age, based on learning and experience. Since the 1970s, a series of studies (2-9) has confirmed that infants even as young as a few hours old can imitate proprioceptively guided behaviors. Despite these findings, neonatal imitation remained a controversial "fuzzy phenomenon" (10). Several studies failed to replicate the phenomenon (11-14), and it was even regarded as artefact by some researchers (15). The confusion about neonatal imitation in part originates from the fact that most movements of neonates were regarded as unintentional until Van der Meer et al. (16) showed that newborn infants can purposefully control their arm resistance against small forces. Recent research showed that most neonatal behaviors, including neonatal reflexes, such as rooting, sucking, and imitation, are flexible and goal-directed behaviors (17). Nagy and Molnar (18,19) reported that neonates not only are able to imitate tongue protrusion gestures but also started to initiate the previously imitated gestures and to engage in long-lasting imitation/initiation "conversation" with the experimenter. Imitations and initiations were coupled with opposite heart rate changes during these dialogues and may indicate a prospective control of a new movement (heart rate increase during imitations) and an attention to an expected reply (heart rate decrease during initiations).Imitation is still lacking an ethologic, and neurophysiologic description in neonates. Why newborn infants imitate and how they can do it are still unanswered questions, although various models have been proposed. Imitation has been described as an unconditioned reflex, a circular reaction (20) or a secondary circular reaction (1), and as an innate releasing mechanism (21). It has been explained as a product of associative learning (22) or instrumental learning (23). Recent explanations include the theory of intermodal mapping (3,24) and the mirror neuron system model (25,26). Although these models successfully explain several aspects of neonatal imitation, none of them is able to describe ...

Sobre a relação entre filogenia e ontogenia no desenvolvimento da lateralidade na infância

“…Particularmente durante o desenvolvimento infantil, têm sido observados comportamentos precocemente lateralizados. Estudos com fetos e neonatos evidenciam o estabelecimento precoce de preferência pelo uso de uma das mãos (de Vries et al, 2001;Michel & Harkins, 1986;Michel, Ovrut, & Harkins, 1985;Rönnqvist & Domellof, 2006) e a manifestação de características comportamentais que denotam desempenho mais refinado com um lado do corpo em comparação com o lado contrário (Caplan & Kinsbourne, 1976;Domellöf, Rönnqvist, & Hopkins, 2007;Nagy et al, 2005). Essas evidências têm sido interpretadas como indício de que assimetrias estruturais na arquitetura dos hemisférios cerebrais estão na raiz do desenvolvimento da lateralidade humana.…”

Associative sequence learning: the role of experience in the development of imitation and the mirror system

“…It has been widely assumed that the human ability to solve the correspondence problem is innate (Meltzoff & Moore 1977Meltzoff & Decety 2003;Nagy et al 2005;Nagy 2006). This assumption is based primarily on data suggesting that newborn infants can imitate a range of different movements (discussed below).…”

Preferência manual na ação de alcançar em bebês em função da localização espacial do alvo

“…Embora a manualidade da mãe seja um elemento potencialmente importante no desenvolvimento da lateralidade infantil, por efeito de comportamento imitativo dos bebês (cf. Fagard & Lemoine, 2006;Nagy et al, 2005), os dados aqui apresentados sugerem que outros aspectos possuem maior peso no estabelecimento da preferência manual em estágios iniciais do desenvolvimento motor. Em consonância com o efeito de alcances ipsilaterais aqui observado, a disposição espacial de brinquedos no espaço de permanência do bebê poderia ser um aspecto importante da lateralização do comportamento manual, assim como outros elementos que tornem o ambiente cotidiano do bebê assimétrico.…”

“…O experimentador apresentava os brinquedos ao bebê com as duas mãos, para prevenir que a mão usada pelo experimentador influenciasse a escolha da mão pelo bebê (cf. Fagard & Lemoine, 2006;Nagy et al, 2005).…”