Adding pieces to the puzzle: a commentary

In Jensen's theme paper she did an excellent job of outlining and explaining ways in which motor developmentalists can use the tools of biomechanics and engineering to address research questions. We extend her thorough efforts in two ways. First, we highlight the communication value provided by the precision of biomechanics terminology, and second, we reinforce the need to embed motion (the kinematics and kinetics) in context and function in order to understand the complexity of behaviour. We illustrate how one biomechanical tool, mechanical models, can facilitate this and provide insight to the development of control. Copyright © 2005 John Wiley & Sons, Ltd.     

Carpal tunnel mechanics and its relevance to carpal tunnel syndrome

The carpal tunnel is an elaborate biomechanical structure whose pathomechanics plays an essential role in the development of carpal tunnel syndrome. The purpose of this article is to review the movement related biomechanics of the carpal tunnel together with its anatomical and morphological features, and to describe the pathomechanics and pathophysiology associated with carpal tunnel syndrome. Topics of discussion include biomechanics of the median nerve, flexor tendons, subsynovial tissue, transverse carpal ligament, carpal tunnel pressure, and morphological properties, as well as mechanisms for biomechanical improvement and physiological restoration. It is our hope that the biomechanical knowledge of the carpal tunnel will improve the understanding and management of carpal tunnel syndrome.     

Intention and Motor Representation in Purposive Action

Are there distinct roles for intention and motor representation in explaining the purposiveness of action? Standard accounts of action assign a role to intention but are silent on motor representation. The temptation is to suppose that nothing need be said here because motor representation is either only an enabling condition for purposive action or else merely a variety of intention. This paper provides reasons for resisting that temptation. Some motor representations, like intentions, coordinate actions in virtue of representing outcomes; but, unlike intentions, motor representations cannot feature as premises or conclusions in practical reasoning. This implies that motor representation has a distinctive role in explaining the purposiveness of action. It also gives rise to a problem: were the roles of intention and motor representation entirely independent, this would impair effective action. It is therefore necessary to explain how intentions interlock with motor representations. The solution, we argue, is to recognise that the contents of intentions can be partially determined by the contents of motor representations. Understanding this content‐determining relation enables better understanding how intentions relate to actions.     

Children show limited movement repertoire when learning a novel motor skill

Examining age differences in motor learning using real‐world tasks is often problematic due to task novelty and biomechanical confounds. Here, we investigated how children and adults acquire a novel motor skill in a virtual environment. Participants of three different age groups (9‐year‐olds, 12‐year‐olds, and adults) learned to use their upper body movements to control a cursor on a computer screen. Results showed that 9‐year‐old and 12‐year‐old children showed poorer ability to control the cursor at the end of practice. Critically, when we investigated the movement coordination, we found that the lower task performance of children was associated with limited exploration of their movement repertoire. These results reveal the critical role of motor exploration in understanding developmental differences in motor learning.     

The early development of human mirror mechanisms: evidence from electromyographic recordings at 3 and 6 months

In primates and adult humans direct understanding of others' action is provided by mirror mechanisms matching action observation and action execution (e.g. Casile, Caggiano & Ferrari, 2011). Despite the growing body of evidence detailing the existence of these mechanisms in the adult human brain, their origins and early development are largely unknown. In this study, for the first time, electromyographic (EMG) measures were used to shed light on the emergence of mirror motor mechanisms in infancy. EMG activity was recorded while 6‐ and 3‐month‐old infants watched two videos displaying an agent reaching for, grasping and bringing an object either to the mouth or to the head. Results indicate that the motor system of 6‐month‐olds, but not 3‐month‐olds, was recruited and selectively modulated during observation of the goal‐directed actions, favoring the idea that mirror mechanisms driving action understanding gradually emerge during early development.     

Towards explaining the “how” of positive orientation: The beliefs‐affect‐engagement model

As a higher order latent construct, positive orientation captures the common core of an individual's beliefs concerning oneself, life, and the future. This article aims at explaining how positive orientation may relate to activity engagement and stimulate persistence in action. It presents the beliefs‐affect‐engagement model, postulating that positive orientation stimulates positive affect, which in turn fosters activity engagement. A distinction between the trait and state components of positive orientation also is made, and specific mechanisms explaining engagement and persistence concerning the trait and two state components of each construct (relatively stable and temporal‐specific aspects of a state) are discussed. The proposed model may contribute to further development of the positive orientation theory.     

Risky visuomotor choices during rapid reaching in childhood

Many everyday actions are implicit gambles because imprecisions in our visuomotor systems place probabilities on our success or failure. Choosing optimal action strategies involves weighting the costs and gains of potential outcomes by their corresponding probabilities, and requires stable representations of one's own imprecisions. How this ability is acquired during development in childhood when visuomotor skills change drastically is unknown. In a rewarded rapid reaching task, 6‐ to 11‐year‐old children followed ‘risk‐seeking’ strategies leading to overly high point‐loss. Adults' performance, in contrast, was close to optimal. Children's errors were not explained by distorted estimates of value or probability, but may reflect different action selection criteria or immature integration of value and probability information while planning movements. These findings provide a starting point for understanding children's risk‐taking in everyday visuomotor situations when suboptimal choices can be dangerous. Moreover, children's risky visuomotor decisions mirror those reported for non‐motor gambles, raising the possibility that common processes underlie development across decision‐making domains.     

Representation and learning in motor action – Bridges between experimental research and cognitive robotics

To gain a better understanding of the functionality of representation and categorization in action and interaction, it is fundamental that researchers understand how movements are represented in long-term memory. It is our position that human motor control requires that our actions be planned and represented in terms of intended perceptual effects and future task demands, and that the individual has a well-structured mental representation of the task so that the movement can be carried out successfully. Basic Action Concepts (BACs) are identified as major building blocks of cognitive representation in long-term memory, which are cognitive tools used to master the functional demands of movement tasks. In this paper, we consider relevant issues in research methodology and present an experimental method that can be used to assess action-relevant representational structures. This method permits us to observe the strong relationship between cognitive representation and performance in manual action. For example, the specific differences in the mental representations of participants are strongly related to skill level, as well as biomechanical and task constraints. We then discuss results from our learning experiments, where we have examined the development and changes in cognitive representation over time. From these experiments we have found that cognitive reference structures include task-specific spatial information, which provides the basis for action control in skilled voluntary movement. We have implemented these results on various robotic platforms. We argue that the insights gained from various experimental approaches in the field of cognitive psychology and motor control enable researchers to explore the possibilities and limitations of artificial control architectures in robot systems. Finally, we argue that this is not a unidirectional process. Researchers from the field of cognitive psychology and motor control can profit from the advances in technological systems, which enhance the understanding of human motor control in skilled voluntary action.     

Social Support in the Workplace and Training Transfer: A longitudinal analysis

Training transfer is crucial for workplace effectiveness, yet some of its social support antecedents are not well investigated. We examine the extent to which two forms of social support (from the organization and the supervisor) predict training transfer and propose several related processes explaining these influences. First, social support enhances training self‐efficacy, increases trainees' mastery (learning) goal orientation, and their motivation to transfer. In turn, we propose that these individual factors are positively related to training‐related cognitions. We test and confirm our model in a longitudinal study based on a sample of 111 employees. The results contribute to a better understanding of organization‐ and supervisor‐based social support as predictors of transfer, and clarify several important related mechanisms.     

From understanding others' needs to prosocial action: Motor and social abilities promote infants' helping

In the present study, we test the main hypothesis that infants' understanding of others' needs translates into helping behavior, when critical motor and social competencies have emerged, early in the second year. We assessed the understanding of others' needs in an eye‐tracking paradigm and the helping behavior of 10‐ (n = 41) and 16‐month‐olds (n = 37). Furthermore, we assessed the motor and social abilities of 16‐month‐olds. Critically, while infants understood others' needs already at 10 months, fine motor and social interaction skills moderated the link between infants' prosocial understanding and helping behavior at 16 months. This provides first evidence that infants' helping behavior relates to their understanding of others' needs. Furthermore, we found that fine motor, gross motor, and social interaction skills predicted early helping behavior by themselves. These findings highlight that the emergence of infants' helping behavior is the result of a developmental system that includes infants' understanding of others' needs and also their motor and social competencies. The link between infants' understanding of others' needs and their early helpful actions provide further support for the prosocial nature of early helping behavior.     

Understanding the effects of one's actions upon hidden objects and the development of search behaviour in 7‐month‐old infants

Infants' understanding of how their actions affect the visibility of hidden objects may be a crucial aspect of the development of search behaviour. To investigate this possibility, 7‐month‐old infants took part in a two‐day training study. At the start of the first session, and at the end of the second, all infants performed a search task with a hiding‐well. On both days, infants had an additional training experience. The ‘Agency group’ learnt to spin a turntable to reveal a hidden toy, whilst the ‘Means‐End’ group learnt the same means‐end motor action, but the toy was always visible. The Agency group showed greater improvement on the hiding‐well search task following their training experience. We suggest that the Agency group's turntable experience was effective because it provided the experience of bringing objects back into visibility by one's actions. Further, the performance of the Agency group demonstrates generalized transfer of learning across situations with both different motor actions and stimuli in infants as young as 7 months.     

Sociomotor action control

Our actions affect the behavior of other people in predictable ways. In the present article, we describe a theoretical framework for action control in social contexts that we call sociomotor action control. This framework addresses how human agents plan and initiate movements that trigger responses from other people, and we propose that humans represent and control such actions literally in terms of the body movements they consistently evoke from observers. We review evidence for this approach and discuss commonalities and differences to related fields such as joint action, intention understanding, imitation, and interpersonal power. The sociomotor framework highlights a range of open questions pertaining to how representations of other persons’ actions are linked to one’s own motor activity, how specifically they contribute to action initiation, and how they affect the way we perceive the actions of others.     

The personality basis of justice: The five‐factor model as an integrative model of personality and procedural fairness effects on cooperation

Building upon the self‐based model of cooperation (De Cremer & Tyler, 2005 ), the present study investigates the relationship between the five‐factor model (FFM) and cooperation. Study 1 (N = 56), an experiment conducted in the laboratory, and Study 2 (N = 116), a field study conducted in an organisational context, yielded a moderator effect between neuroticism and procedural fairness in explaining cooperation. Study 3 (N = 177) showed that this moderator effect was mediated by the self‐uncertainty and relational variables proposed by the self‐based model of cooperation. It is concluded that the FFM is useful in explaining cooperation and contributes to a better understanding of (procedural) fairness effects. Moreover, the necessity to build integrative, multi‐level models that combine core and surface aspects of personality to explain the effects of fairness on cooperation is elaborated upon. Copyright © 2008 John Wiley & Sons, Ltd.     

Specialization of the motor system in infancy: from broad tuning to selectively specialized purposeful actions

In executing purposeful actions, adults select sufficient and necessary limbs. But infants often move goal‐irrelevant limbs, suggesting a developmental process of motor specialization. Two experiments with 9‐ and 12‐month‐olds revealed gradual decreases in extraneous movements in non‐acting limbs during unimanual actions. In Experiment 1, 9‐month‐olds produced more extraneous movements in the non‐acting hand/arm and feet/legs than 12‐month‐olds. In Experiment 2, analysis of the spatiotemporal dynamics of infants’ movements revealed developmental declines in the spatiotemporal coupling of movements between acting and non‐acting arms. We also showed that the degree of specialization in infants’ unimanual actions is associated with individual differences in motor experience and visual attention, indicating the experience‐dependent and broad functional nature of these developmental changes. Our study provides important new insights into motor development: as in cognitive domains, motor behaviours are initially broadly tuned to their goal, becoming progressively specialized during the first year of life.     

Understanding Fallible Warrant and Fallible Knowledge: Three Proposals

One of contemporary epistemology's more important conceptual challenges is that of understanding the nature of fallibility. Part of why this matters is that it would contribute to our understanding the natures of fallible warrant and fallible knowledge. This article evaluates two candidates – and describes a shared form of failing. Each is concealedly infallibilist. This failing is all‐too‐representative of the difficulty of doing justice to the notion of fallibility within the notions of fallible warrant and fallible knowledge. The article ends with a proposal for an improved (even if schematic) form of conception of fallible warrant and fallible knowledge.     

Relations between infants’ emerging reach‐grasp competence and event‐related desynchronization in EEG

Recent reports of similar patterns of brain electrical activity (electroencephalogram: EEG) during action execution and observation, recorded from scalp locations over motor‐related regions in infants and adults, have raised the possibility that two foundational abilities – controlling one's own intentional actions and perceiving others’ actions – may be integrally related during ontogeny. However, to our knowledge, there are no published reports of the relations between developments in motor skill (i.e. recording actual motor skill performance) and EEG during both action execution and action observation. In the present study we collected EEG from 21 9‐month‐olds who were given opportunities to reach for toys and who also observed an experimenter reach for toys. Event‐related desynchronization (ERD) was computed from the EEG during the reaching events. We assessed infants’ reaching‐grasping competence, including reach latency, errors, preshaping of the hand, and bimanual reaches, and found that desynchronization recorded in scalp electrodes over motor‐related regions during action observation was associated with action competence during execution. Infants who were more competent reachers, compared to less competent reachers, exhibited greater ERD while observing reaching‐grasping. These results provide initial evidence for an early emerging neural system integrating one's own actions with the perception of others’ actions.     

Joint action: bodies and minds moving together

The ability to coordinate our actions with those of others is crucial for our success as individuals and as a species. Progress in understanding the cognitive and neural processes involved in joint action has been slow and sparse, because cognitive neuroscientists have predominantly studied individual minds and brains in isolation. However, in recent years, major advances have been made by investigating perception and action in social context. In this article we outline how studies on joint attention, action observation, task sharing, action coordination and agency contribute to the understanding of the cognitive and neural processes supporting joint action. Several mechanisms are proposed that allow individuals to share representations, to predict actions, and to integrate predicted effects of own and others' actions.