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 ...

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The empirical foundation of the 'placebo effect' is presented briefly, which is followed by the meta-analysis of the relatively few published reports that have investigated placebo effects in sports performance. Based on the analysis of the fourteen studies included in the meta-analysis, an overall medium effect size (0.4, 95% CI ranged from 0.24 to 0.56) was found. Homogeneity of effect sizes (χ 2 (13, N = 196) = 9.35, p = 0.75) and the feasibility of possible explanation models were also tested. In various sports (e.g. cycling, running, weightlifting) the investigation of the placebo effect on various physiological or performance measures (e.g. muscle power, heart rate, running speed) and psychological attributes (e.g. perceived exertion, post-experiment interviews) yielded significant results. Indeed, the common finding of the reviewed studies was that from the point of view of the athletes there is substantial performance enhancement as a result of different forms of placebos. However, the interpretation of some of the results may be limited by methodological shortcomings. Based on the reviewed articles and further questions emerging from them, methodological recommendations as well as possible research ideas are suggested for further inquiries in the area.Keywords: placebo effect, meta-analysis, expectation, belief, sport, physical exercise, mechanism, nocebo Placebo-Effekt im Bereich Sport: Metaanalyse: Die Grundlagen der Erforschung des Placebo-Effekts werden kurz geschildert, sodann werden die Ergebnisse unserer Metaanalyse vorgestellt, die auf Grundlage einiger Studien zur Untersuchung des messbaren Placebo-Effekts bei Sportleistungen durchgeführt wurde. Auf Grundlage der in die Metaanalyse integrierten 14 Studien wurde eine mittlere Wirkungsgröße festgestellt (0,4, mit 95% CI 0,24-0,56). Es wurden die Homogenität der Wirkungsgrößen (χ 2 (13, N = 196) = 9,35, p = 0,75), sowie die Möglichkeit der