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Rein R.,German Sport University Cologne | Bril B.,Groupe de Recherche Apprentissage et Contexte | Nonaka T.,Kibi International University
American Journal of Physical Anthropology | Year: 2013

Stone tool-use and manufacture is seen as an important skill during the evolution of our species and recently there has been increased interest in the understanding of perceptual-motor abilities underlying this skill. This study provides further information with respect to the motor strategies used during stone knapping. Kinematics of the striking arm were recorded in expert and novice knappers while producing flakes of two different sizes. Using Uncontrolled Manifold Analysis, the results showed that knappers structure joint angle movements such that the hammer trajectory variability is minimized across trials, with experts displaying significantly smaller variability compared with novices. Principal component analysis further revealed that a single component captures the complexity of the strike and that the strike is governed by movements of the elbow and the wrist. Analysis of movement velocities indicated that both groups adjusted movement velocities according to flake size although experts used smaller hammer, wrist, and elbow velocities in both flake conditions compared with novices. The results suggest that while the gross striking movement is easy to replicate for a novice knapper, it requires prolonged training before a knapper becomes attuned to the finer details necessary for controlled flaking. © 2013 Wiley Periodicals, Inc.


Nonaka T.,Groupe de Recherche Apprentissage et Contexte | Bril B.,Groupe de Recherche Apprentissage et Contexte | Rein R.,German Sport University Cologne
Journal of Human Evolution | Year: 2010

The aim of the current study was to provide detailed data on the skill at controlling conchoidal fracture, data that may be used to help infer the processes responsible for generating the technological diversity observed in Early Stone Age sites. We conducted an experiment with modern stone knappers with different skill levels and systematically analyzed not only the products of flaking (i.e., detached flakes) but also the intentions prior to flaking, as well as the actions taken to control the shape of a flake through direct hard-hammer percussion. Only modern stone knappers with extensive knapping experience proved capable of predicting and controlling the shape of a flake, which indicated the significant difficulty of controlling the shape of flakes. Evidence was found that knowing the consequence of a strike given to a core at hand requires the acute exploration of the properties of the core and hammerstone to comply with the higher-order relationship among potential platform variables, kinetic energy of the hammerstone at impact, and flake dimension that reflects the constraints of conchoidal fracture. We argue that without this ability, controlling the shape of a flake or the organized débitage of flakes observed in some of the Early Stone Age sites may not have been possible. We further suggest that, given the difficulty and the nature of the skill, the evidence of precise control of conchoidal fracture in the Early Stone Age record may be indicative of the recurrence of a learning situation that allows the transmission of the skill, possibly through providing the opportunities for first-hand experience. © 2010 Elsevier Ltd.


Rein R.,German Sport University Cologne | Nonaka T.,Kobe University | Bril B.,Groupe de Recherche Apprentissage et Contexte
PLoS ONE | Year: 2014

The earliest direct evidence for tool-use by our ancestors are 2.6 million year old stone tools from Africa. These earliest artifacts show that, already, early hominins had developed the required advanced movement skills and cognitive capacities to manufacture stone tools. Currently, it is not well understood, however, which specific movement skills are required for successful stone knapping and accordingly it is unknown how these skills emerged during early hominin evolution. In particular, it is not clear which striking movements are indicative of skilled performance, how striking movement patterns vary with task and environmental constraints, and how movement patterns are passed on within social groups. The present study addresses these questions by investigating striking movement patterns and striking variability in 18 modern stone knappers (nine experienced and nine novices). The results suggest that no single movement pattern characterizes successful stone knapping. Participants showed large inter-individual movement variability of the elementary knapping action irrespective of knapping experience and knapping performance. Changes in task- and environmental constraints led knappers to adapt their elementary striking actions using a combination of individual and common strategies. Investigation of striking pattern similarities within social groups showed only partial overlap of striking patterns across related individuals. The results therefore suggest that striking movement patterns in modern stone knappers are largely specific to the individual and movement variability is not indicative of knapping performance. The implications of these results for the development of percussive traditions are discussed. © 2014 Rein et al.


Rein R.,Groupe de Recherche Apprentissage et Contexte | Button C.,University of Otago | Davids K.,Queensland University of Technology | Summers J.,University of Tasmania
Motor Control | Year: 2010

The present paper proposes a technical analysis method for extracting information about movement patterning in studies of motor control, based on a cluster analysis of movement kinematics. In a tutorial fashion, data from three different experiments are presented to exemplify and validate the technical method. When applied to three different basketball-shooting techniques, the method clearly distinguished between the different patterns. When applied to a cyclical wrist supination-pronation task, the cluster analysis provided the same results as an analysis using the conventional discrete relative phase measure. Finally, when analyzing throwing performance constrained by distance to target, the method grouped movement patterns together according to throwing distance. In conclusion, the proposed technical method provides a valuable tool to improve understanding of coordination and control in different movement models, including multiarticular actions. © 2010 Human Kinetics, Inc.


Bril B.,Groupe de Recherche Apprentissage et Contexte | Bril B.,University of Paris Descartes | Parry R.,Paris-Sorbonne University | Parry R.,French Institute of Health and Medical Research | And 2 more authors.
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2015

Various authors have suggested similarities between tool use in early hominins and chimpanzees. This has been particularly evident in studies of nutcracking which is considered to be the most complex skill exhibited by wild apes, and has also been interpreted as a precursor of more complex stoneflaking abilities. It has been argued that there is no major qualitative difference between what the chimpanzee does when he cracks a nut and what early hominins didwhen they detached a flake from a core. In this paper, similarities and differences between skills involved in stone-flaking and nut-cracking are explored through an experimental protocol with human subjects performing both tasks. We suggest that a ‘functional’ approach to percussive action, based on the distinction between functional parameters that characterize each task and parameters that characterize the agent’s actions and movements, is a fruitful method for understanding those constraints which need to be mastered to perform each task successfully, and subsequently, the nature of skill involved in both tasks. © 2015 The Author(s) Published by the Royal Society. All rights reserved.


Coubard O.A.,The Neuropsychological Laboratory | Ferrufino L.,The Neuropsychological Laboratory | Nonaka T.,Kibi International University | Zelada O.,Higher University of San Simón | And 4 more authors.
Frontiers in Aging Neuroscience | Year: 2014

Understanding the human aging of postural control and how physical or motor activity improves balance and gait is challenging for both clinicians and researchers. Previous studies have evidenced that physical and sporting activity focusing on cardiovascular and strength conditioning help older adults develop their balance and gait and/or decrease their frequency of falls. Motor activity based on motor-skill learning has also been put forward as an alternative to develop balance and/or prevent falls in aging. Specifically dance has been advocated as a promising program to boost motor control. In this study, we examined the effects of contemporary dance (CD) on postural control of older adults. Upright stance posturography was performed in 38 participants aged 54-89 years before and after the intervention period, during which one half of the randomly assigned participants was trained to CD and the other half was not trained at all (no dance, ND). CD training lasted 4 weeks, 3 times a week. We performed classical statistic scores of postural signal and dynamic analyses, namely signal diffusion analysis (SDA), recurrence quantification analysis (RQA), and detrended fluctuation analysis (DFA). CD modulated postural control in older trainees, as revealed in the eyes closed condition by a decrease in fractal dimension and an increase in DFA alpha component in the mediolateral plane. The ND group showed an increase in length and mean velocity of postural signal, and the eyes open a decrease in RQA maximal diagonal line in the anteroposterior plane and an increase in DFA alpha component in the mediolateral plane. No change was found in SDA in either group. We suggest that such a massed practice of CD reduced the quantity of exchange between the subject and the environment by increasing their postural confidence. Since CD has low-physical but high-motor impact, we conclude that it may be recommended as a useful program to rehabilitate posture in aging. © 2014 Coubard, Ferrufino, Nonaka, Zelada, Bril and Dietrich.


Nonaka T.,Kibi International University | Bril B.,Groupe de Recherche Apprentissage et Contexte
Human Movement Science | Year: 2012

In human manual activities, the two hands are often engaged in differentiated roles while cooperating with each other to produce an integrated outcome. Using recurrence methods, we studied the asymmetric bimanual action involved in stone bead production by craftsmen of different skill levels, and examined (a) how the control of unilateral movement is embedded in that of a bimanual system, and (b) how the behavior of a bimanual system is embedded in the context of the function performed in the world. Evidence was found that the movements of the two hands of experts were functionally linked, reflecting the roles assumed by each hand. We further found that only the dynamics of bimanual coordination of experts differentiated the functional requirements of different sub-goals. These results suggest that expertise in this skilled bimanual action lies in the nesting of functionally specific adjustments at different levels of a control hierarchy. © 2010 Elsevier B.V.


PubMed | Groupe de Recherche Apprentissage et Contexte
Type: Journal Article | Journal: Journal of experimental psychology. Human perception and performance | Year: 2010

Tool use can be considered a particularly useful model to understand the nature of functional actions. In 3 experiments, tool-use actions typified by stone knapping were investigated. Participants had to detach stone flakes from a flint core through a conchoidal fracture. Successful flake detachment requires controlling various functional parameters simultaneously. Accordingly, our goals were twofold: (a) to examine the regulation of kinetic energy by varying the properties of the hammers and the goal, and (b) to characterize the difference in action regulation across skill levels. All groups were able to modify their actions according to changes in task goals, but only experts displayed fine-tuning to functional parameters (i.e., regulate actions according to changes in hammer weight in a manner that left kinetic energy unchanged). Expertise is considered to depend on the identification of the interactions between functional parameters.


PubMed | Groupe de Recherche Apprentissage et Contexte
Type: | Journal: Frontiers in human neuroscience | Year: 2012

As society ages and the frequency of falls increases, counteracting gait and posture decline is a challenging issue for countries of the developed world. Previous studies have shown that exercise and hazard management help to improve balance and/or decrease the risks for falling in normal aging. Motor activity based on motor-skill learning, particularly dance, can also benefit balance and decreases falls with age. Recent studies have suggested that older dancers have better balance, posture, or gait than non-dancers. Additionally, clinical or laboratory measures have shown improvements in some aspects of balance after dance interventions in elderly trainees. This study examined the impact of contemporary dance (CD) and of fall prevention (FP) programs on postural control of older adults. Posturography of quiet upright stance was performed in 41 participants aged 59-86years before and after 4.4-month training in either CD or FP once a week. Though classical statistic scores failed to show any effect, dynamic analyses of the center-of-pressure displacements revealed significant changes after training. Specifically, practice of CD enhanced the critical time interval in diffusion analysis, and reduced recurrence and mathematical stability in recurrence quantification analysis, whereas practice of FP induced or tended to induce the reverse patterns. Such effects were obtained only in the eyes open condition. We suggest that CD training based on motor improvisation favored stochastic posture inducing plasticity in motor control, while FP training based on more stereotyped behaviors did not.

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