Yeou-Teh Liu

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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 accounted for(More)
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 attractor(More)
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 further(More)
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 condition over 5(More)
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(More)
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 life span.(More)
Two experiments investigated a new approach to decomposing the contributions of spatial and temporal constraints to an integrated single space-time performance score in the movement speed-accuracy relation of a line drawing task. The mean and variability of the space-time performance error score were lowest when the task space and time constraint(More)
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 a control(More)
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 about an(More)
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 there is no(More)