@proceedings {529,
	title = {Impact of visual error augmentation methods on task performance and motor adaptation},
	year = {2009},
	pages = {793-798},
	abstract = {<p>We hypothesized that augmenting the visual error feedback provided to subjects training in a point-to-point reaching task under visual distortion would improve the amount and speed of adaptation. Previous studies showing that human learning is error-driven and that visual error augmentation can improve the rate at which subjects decrease their trajectory error in such a task provided the motivation for our study. In a controlled experiment, subjects were required to perform point-to- point reaching movements in the presence of a rotational visual distortion. The amount and speed of their adaptation to this distortion were calculated based on two performance measures: trajectory error and hit time. We tested how three methods of error augmentation (error amplification, traditional error offsetting, and progressive error offsetting) affected the amount and speed of adaptation, and additionally propose definitions for {\textquotedblleft}amount{\textquotedblright} and {\textquotedblleft}speed{\textquotedblright} of adaptation in an absolute sense that are more practical than definitions used in previous studies. It is concluded that traditional error offsetting promotes the fastest learning, while error amplification promotes the most complete learning. Progressive error offsetting, a novel method, resulted in slower training than the control group, but we hypothesize that it could be improved with further tuning and indicate a need for further study of this method. These results have implications for improvement in motor skill learning across many fields, including rehabilitation after stroke, surgical training, and teleoperation.</p>},
	attachments = {https://mahilab.rice.edu/sites/default/files/publications/529-Celik2009ICORRpublished.pdf},
	author = {Ozkan Celik and Powell, Dane and O{\textquoteright}Malley, M.K.}
}
@proceedings {674,
	title = {Intermittency of slow arm movements increases in distal direction},
	year = {2009},
	pages = {4499-4504},
	address = {St. Louis, MO},
	abstract = {<p>When analyzed in the tangential speed domain, human movements exhibit a multi-peaked speed profile which is commonly interpreted as evidence for submovements. At slow speeds, the number of the peaks increases and the peaks also become more distinct, corresponding to non-smoothness or intermittency in the movement. In this study, we evaluate two potential sources proposed in the literature for the origins of movement intermittency and conclude that intermittency is more likely due to noise in the neuromuscular system as opposed to a central movement planner that generates intermittent plans. This conclusion is based on the assumption that the central planner would be expected to introduce similar levels of intermittency for different joints, while accumulating noise in the neuromuscular circuitry would be expected to exhibit itself as increase in noise in distal direction. We have used a 3D motion capture system to record trajectories of fingertip, wrist, elbow and shoulder as five participants completed a simple manual circular tracking task at various constant speed levels. Statistical analyses indicated that movement intermittency, quantified by a number of peaks metric, increased in distal direction, supporting the noise model for origins of intermittency. Movement speed was determined to have a significant effect on intermittency, while orientation of the task plane showed no significance.</p>},
	attachments = {https://mahilab.rice.edu/sites/default/files/publications/674-Celik2009IROS.pdf},
	author = {Ozkan Celik and Gu, Qin and Deng, Zhigang and O{\textquoteright}Malley, M.K.}
}
