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Publications (79)
Human movement takes place in both space and
time so that measures of movement accuracy in space are made
with respect to time, and vice-versa providing a foundation to
the proposal of the complementarity of spatial and temporal
error in aiming movements. We examined this hypothesis in
both the standard Fitts and Peterson discrete movement speedacc...
Human movement takes place in both space and time, and measures of movement accuracy in space are always made with respect to time, and vice-versa. The Fitts’ aiming protocol can be interpreted as filling space with time and the reciprocal paradigm as filling time with space. Purpose: Here we examined the effects of target movement time on the emer...
The specificity and generality of practice effects are central issues in motor learning, retention and transfer. The current study implemented the piecewise linear map model to analyze practice effects on five different target time conditions in discrete timing tasks. Five individualized target times were constructed and tested for eighteen adult h...
There is a long-held view that discrete movements aimed to a target are composed of a sequence of movement units (sub-movements) that have different roles in motor control (e.g., initial impulse, error correction and movement termination) depending on the task constraints (e.g., spatial-temporal requirements). Here we report findings from the manip...
In this paper we review studies that have identified collective variables (order parameters) in movement coordination, control and skill with emphasis on whole-body multiple joint degree of freedom (DF) tasks. Collective variables of a dynamical system have been proposed formally and informally from a diverse set of perceptual-motor tasks, from whi...
In complex adaptive systems approaches to perceptual-motor control the mapping between the different categories of task dynamics: namely, task outcome, collective variable, neuromuscular synergies and individual joint configurations is a central theoretical issue, that has been primarily studied in bimanual tasks. Here we report an investigation in...
In discrete aiming movements the task criteria of time-minimization to a spatial target (e.g., Fitts, 1954) and time-matching to a spatial-temporal goal (e.g., Schmidt et al., 1979) tend to produce different functions of the speed-accuracy trade-off. Here we examined whether the task-related movement speed-accuracy characteristics were due to diffe...
For the past 65 years, researchers have applied the Fitts’ Law extensively to understand the tradeoff of speed and accuracy of human movements. The literature, however, often showed discrepancies between the end points distributions and the target sizes that also indirectly lead to the different movement amplitudes. In addition, the arrangement of...
We investigated fencers’ perception of affordances of the opponent by asking them to estimate the reach-ability (length of lunge) of the opponent that varied in height and moved toward them in different paces. Their task was to initiate a backward step at the moment that they perceived to be reached by the opponent in a lunge attack. All trials wer...
There is preliminary evidence that there are several types of submovements in movement aiming that reflect different processes of control and can result from particular task constraints. The purpose of the study was to investigate the effect of movement space and time task criteria on the prevalence of different submovement control characteristics...
Spreadsheet presenting number of submovements for each individual in five space-time conditions.
(XLSX)
Spreadsheet presenting type of submovements for each individual in five space-time conditions.
(XLSX)
We investigated the coordination of balance and propulsion processes in learning to ride a unicycle through a principal component analysis (PCA) of the nature and number of functional degrees of freedom (DOF) in the movement coordination patterns. Six participants practiced unicycle riding on an indoor track for 28 sessions over separate days. The...
Woodworth’s (1989) initial investigation distinguished the role of a current control phase from the discontinuous trajectory of movement and showed that it is a main factor for movement accuracy. The existence of submovements underlying movement kinematic trajectory has been the focus of many studies. Here we contrast 3 direct and objective movemen...
The speed-accuracy trade-off has been a long standing interest in the field of motor behavior and cognitive psychology. The essence of the speed-accuracy relation is that with an increase in movement speed there is a concomitant decrease in movement spatial accuracy. However, human movement always take place in both space and time, it has been show...
S-Shaped change in performance outcome has long been considered to be a pathway of motor learning, but there is little or no evidence for it. The experiment investigated the hypothesis that S-shaped motor learning as reflected in the task outcome is a product of a transition in the movement coordination dynamics as a function of practice acting as...
Recent studies have shown more than one time scale of change in the movement dynamics of practice. Here, we decompose the drift and diffusion dynamics in adaptation to performing discrete aiming movements with different space-time constraints. Participants performed aiming movements on a graphics drawing board to a point target at 5 different space...
Learning and development over the lifespan influence the dynamics of the human motor system. Our ideas about the dynamics of motor learning and development are grounded in the phenomena of the continuous evolution of movement patterns and outcomes over multiple time scales. In this review, we present examples of time scales distinguishing propertie...
The purpose of this study was to investigate the hypothesis that a self-organized criticality (SOC) practice condition would have a higher improvement rate in performance outcome than a typical progressive difficulty of practice regimen. The roller ball task was used where participants undergo a phase transition from failure to successful performan...
Current literature suggests that mindful learning is beneficial to learning but its links with motor learning is seldom examined. In the present study, we examine the effects of learners' mindfulness disposition on the self-controlled learning of a novel motor task. Thirty-two participants undertook five practice sessions, in addition to a pre-, po...
This study investigated whether the level of practice interacts with the initial conditions (here manipulated as preparatory movements) and task difficulty (ball angular velocity and friction) in determining the stability of movement coordination for a roller ball motor task. Practice level and task difficulty were manipulated as two control parame...
It is well established that there is an increased amount of intraindividual variability with aging in a variety of behavioral contexts. Here, we elaborate from a self-organization and dynamic systems framework to investigate the relevant time scales of variability as a function of aging and their relation to the changes in the amount and structure...
A multiple time scales landscape model is presented that reveals structures of performance dynamics that were not resolved in the traditional power law analysis of motor learning. It shows the co-existence of separate processes during and between practice sessions that evolve in two independent dimensions characterized by time scales that differ by...
Multidimensional exploration of bimanual arm rotation
Haken, Kelso, & Bunz (1985) proposed relative phase (RP) to describe the bimanual coordination pattern, and observed pattern switching from anti-phase to in-phase by increasing the control parameter (frequency). Since then, many studies examined the bifurcation of rhythmic finger movement (M) a...
Complex motor tasks – such as skydiving or landing an airplane – require extensive training and practice of coordinated movement
sequences. But even once the task is learned, experience shows that the proper execution of the task is not guaranteed if
the task is to be performed years, months, or even days after its most recent execution. That is wh...
In this paper we review recent work from our studies of a nonlinear dynamics of motor learning that is grounded in the construct of an evolving attractor landscape. With the assumption that learning is goal-directed, we can quantify the observed performance as a score or measure of the distance to the learning goal. The structure of the dynamics of...
In this chapter we elaborate on the dynamical basis for the time scales of change in motor learning. It is known that in both oscillatory and growth/ decay processes the exponential characterizes the time scales of change. A few characteristic or even multiple time scales can arise from continually evolving landscape dynamics due to bifurcations be...
The change in behavior over time that reflects human motor learning and development has long been thought of as a consequence
of the evolving cycle of system stability and instability [16, 17, 37]. Over the last 25 years or so, the dynamics of this pathway of change in behavior has been modeled using the physical construct
of potential wells that h...
The authors investigated the time scales of the learning of a mirror-tracing task to reexamine G. S. Snoddy's (1926) original claim and the received theoretical view (A. Newell & P. S. Rosenbloom, 1981) that motor learning follows a power law. Adult participants (N = 16) learned the tracing task in either a normal or a reversed visual-image conditi...
This longitudinal study examined the prehensile development of infants (9-37 weeks) under different task constraints (object shape, size and texture). At 9 weeks of age, the infants did not reach or make contact with the objects, but all 10 infants showed goal directed prehensile movement by about 17 weeks. As they continued to age the infants furt...
Human movement reveals the hall mark characteristics of complex systems: namely, many interacting subsystems, multiple interactions within and between levels of analysis, emergence of movement coordination modes, and the exhibition of varying levels of the complexity of system output that continually evolve with learning and development over the li...
The experiments examined qualitative and quantitative changes in the dynamics of learning a novel motor skill (roller ball task) as a function of the manipulation of a control parameter (initial ball speed). The focus was on the relation between the rates of change in performance over practice time and the changing time scales of the evolving attra...
In this paper, we examine the role of degrees of freedom and their degeneracy in learning in the brain–computer interface paradigm. Though the traditional notion of degrees of freedom in motor learning gave emphasis to muscle and joint activity, the broader concept of dimensions of behavior is relevant to brain–computer interface learning where the...
In this commentary, the authors elaborate on the issue of going beyond curve fitting to the drawing of inferences about motor learning. They argue that the agenda of A. Heathcote and S. Brown (2004) is largely a theory-free, curve-fitting enterprise that can be useful for certain aspects of describing behavior change, but that its gold standard of...
This paper presents a unified dynamical systems theory of motor learning and development and addresses the normative order and timing of activities in the infant motor development sequence. The emphasis is on the role of intention in modulating the epigenetic landscapes to the emerging forms of infant motor development and how the evolution of attr...
The authors examined the function for learning a discrete timing task from a dynamical systems perspective rather than solely the traditional curve-fitting viewpoint. Adult participants (N = 8) practiced a single-limb angular movement task of 125 ms over 20 degrees for 200 trials. There was no significant difference in percentage of variance accoun...
A theoretical framework based on the concepts and tools of nonlinear dynamical systems is advanced to account for both the persistent and transitory changes traditionally shown for the learning and development of motor skills. The multiple time scales of change in task outcome over time are interpreted as originating from the system's trajectory on...
In 3 experiments, the authors examined movement space-time variability as a function of the force-time properties of the initial impulse in a movement timing task. In the range of motion and movement time task conditions, peak force, initial rate of force, and force duration were manipulated either independently or in combination across a range of...
In this paper we present a piecewise linear, stochastic map model for discrete timing tasks that describes the trial to trial strategies in relation to a threshold for adaptive change beyond which the dynamics is purely stochastic. The model is a basic difference equation with three parameters, slope, threshold, and noise amplitude that are conside...
Recent accounts of the speed/accuracy relation for motor
tasks have focused on the concept of motor output variability. We
outline the advantages of this approach and the limitation of
Plamondon's model in explaining movement error. We also
examine and present complimentary data for rapid timing tasks.
While these tasks do not meet the present...
The purpose of this study was to examine the influence of posture stability on one-hand catching in skilled adults. Ten female PE major college students participated in the experiment. They practiced the stabilometer task 20 trials a day, 3 days a week for 2 weeks. The balancing time, number of balls caught, as well as the movement kinematics of th...
INTRODUCTION: The movement characteristics of the butterfly stroke make it the most energy demanding style among the four styles in competitive swimming. Therefore the coordination between the arm and the leg becomes extraordinarily important for a successful butterfly swimmer. The aim of this study was to examine the difference of the arm-leg coor...
Self organized criticality (SOC) has been studied as a universal property of complex adaptive systems. In a series of experiments we could show that principles of SOC also apply to a complex class of motor learning tasks. These tasks (e.g., "Roller ball") are characterized by the fact that they do not only exhibit a simple improvement of score valu...
