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Summary of replies to posting on relearning of a modified task.

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  • Summary of replies to posting on relearning of a modified task.

    Dear list members,

    Thank you very much to those who replied to my question on the relearning of a modified task. This is a summary of the replies received for those who are interested. My original question follows the replies.


    D. Gordon E. Robertson, Ph.D. 01/08/02 08:16am
    My guess is that it will require relearning. There is a quick way of training the subjects. Put a force transducer on the oar (boat) or cable (ergometer) and feedback the pulling force to the subject via an oscilloscope or similar device. The biofeedback will permit the subjects to learn the task swiftly and allows you to compare the effectiveness of the stroke in a more detailed way.

    Jim Patton 01/08/02 12:03pm
    The answer, based on the recent findings in reaching studies, is that performance may not be quite as good, but should be learned quite rapidly.
    Research shows that subjects tend to are able to compensate for forces experienced at neighboring workspace locations. However, the effect decays smoothly and quickly with distance from practised locations. here's some papers to look at:

    Thoroughman, KA and Shadmehr, R (2000) Learning of action through adaptive combination of motor primitives. Nature 407: 742-7.

    Shadmehr, R and Moussavi, ZM (2000) Spatial generalization from learning dynamics of reaching movements. Journal of Neuroscience 20: 7807-15.

    Gandolfo, F, Mussa-Ivaldi, FA and Bizzi, E (1996) Motor learning by field approximation. Proceedings of the National Academy of Sciences of the United States of America 93: 3843-6.

    Wesley Pryor 01/08/02 02:04pm
    I'm working in an area with some similarities to your own. I have some ideas about your question, one of which is to see for yourself by taking EMG, but you will have to give me more time to think about my response.

    Paul Ostic 01/09/02 02:22am
    I have no experience that would suggest whether the task would have to be relearned. But I would suggest that it might not be too onerous to include a protocol to evaluate the effects of learning. It would suggest testing for repeatability at +10 and -10 degrees, and if the repeatability is good over several trials and does not show a trend in one direction, then conclude that training/learning is not a factor in your test.

    Antony Hodgson 01/09/02 10:17am
    In our work on reaching movements, we often have a subject learn to make a point to point movement while interacting with a robotic arm programmed to apply various force patterns to the subject's hand. We typically use a paradigm where we switch the characteristics of the force patterns at a certain point in time and then observe the subject learning the new pattern. We also occasionally apply perturbations on random trials and observe how long it takes a subject to return to baseline performance. The time it takes to learn a new force pattern can range from 2 or 3 repetitions up to a hundred or more, depending on the complexity of the new pattern (eg, see Reza Shadmehr's papers for examples of difficult patterns). We often use modestly different patterns and subjects typically take 10-20 movements to fully adjust to the new pattern. For less pathological pattern changes, such as your example of angling the ankle a small amount, I would expect to see full adaptation in under ten trials, if rowing is anything at all like reaching (caveat emptor!). After a subject has learned a field and receives a single unexpected perturbation, they typically return to baseline performance after two or three additional movements.

    Dave Collins 01/08/02 03:48pm
    I am copying the abstract to my dissertation below......

    David R. Collins, Ph.D. University of Connecticut, 1999

    In the present research, the notion of a generalized motor program underlying movement coordination, and instantiated through learning, was interpreted as a coordination dynamics. Three experiments were directed at the potentially beneficial (positive transfer) and potentially adverse (interference) effects of practicing specific aspects of the dynamics on the dynamics as a whole. New measures based in statistical physics and nonlinear dynamics were introduced to evaluate these potential effects.
    The motor task was a bimanual coordination in which the oscillations of manipulanda in the left (L) and right (R) hands were synchronized. The oscillations were such that the end points of each manipulandum repeatedly transcribed a circle. The synchronized circular motions could occur in eight ways (e.g., L and R clockwise, L counterclockwise and R clockwise, and so on) divided into two sets of four by the direction of the left hand. A single potential function V in the bimanual relative phase (that is, a single dynamical rule) incorporates all eight relative-phase patterns and the
    Fokker-Planck equation relates the probability distribution P of relative phase to V.
    In Experiments 1 and 2, only one direction of the left hand was considered, limiting the studied coordination patterns to four in number. In Experiment 3, both rotation directions were considered. The design common to the experimental groups in all three experiments was practice on one pattern (the most simple or the most difficult) or all four patterns of one direction preceded by and followed by a test of all four patterns of one direction. At issue was how (a) the relative-phase probability distributions expressing the locations and strengths of the dynamics's attractors and (b) the recurrent
    structure expressing the determinism of the fine time-scale correlations of the four patterns, changed from pre- to post-test as a function of the specific practice.
    The results of the experiments suggest that the intervening practice, viewed as either facilitating (transfer) or impeding (interference), exerted a general, non-specific effect on the coordination dynamics. The harder coordination patterns (by an immediate post-test) and all patterns (by a delayed post-test) were affected by practice indifferent to the type of pattern that was practiced; specifically, they became more stable (but not more precise) and the component motions increased in dynamical complexity.
    The major lesson of the experiments and their results, however, was methodological. In respect to spatially and temporally complex motor skills, the successful application of more refined quantifiers of learning, transfer and interference processes requires a number of constraints on the experimental manipulations and data collection procedures that are, as yet, poorly understood. Identifying and clarifying them will have to be a primary task of future research. The steps to be taken in this respect constituted the larger part of the discussion. Hopefully, they will inform the next round of analyses directed at the acquisition and retention of movement patterns conducted with the modern tools of statistical physics and nonlinear dynamics.

    Jos Vanrenterghem 01/16/02 11:01pm
    I'm working on the standing vertical jump. We investigate the adjustment of coordination in submaximal executions, relative to the maximal execution. We have seen that subjects learn to jump submaximally in a very fast way, and are now trying to create a theory that fits to our findings. The Generalised Motor Program Theory (Schmidt, RA, 1975) fits into our findings, but we are now wondering how some other findings relate to it.

    Joseph F Seay 01/16/02 10:32am
    *I am working on publishing my thesis with Jim, and I actually looked at power output over different footstretcher positions also. I, however, looked at 5 deg pitches, as opposed to 2.5 deg increments. I did not research fine motor task acclimation, as you are now, and the way we handled acclimation was to allow the rower a five-minute warm-up period at the setting that would be used during their 6-min bout that day. During those 5 min, the rower could do some "power tens" (sets of 10 maximal strokes) to increase his/her intensity, but could not exceed 180 maximal strokes during their warm-up. Our feeling was that these folks row enough that 5 min pre-trial would not affect the testing bout, and that the rowers would not need much time at all to acclimate to the new position, since the stroke is essentially the same. We were also using ergometers, and footstretcher acclimation should probably be considered more carefully if the measurements are being taken in the shell itself (i.e., on the water).

    Dear list members,

    I am currently designing a research project which will involve altering the angle of the foot stretcher (plate a rower puts there feet on) in a boat looking at differences in force outputs. This angle will be altered in 2.5 degree increments. There will be a maximum of 4 increments in any one direction (planta flexion and dorsiflexion) therefore a maximum of 10 degrees change. The subjects will be elite rowers with a minimum of 5 years of rowing experience.

    My question is: Will a change of 2.5 deg at any one time in foot stretcher position require a relearning of the task? (Task = rowing stroke)

    Fisherman and Oxendine (1993) write in a Sport Psychology text that minor changes to technique (e.g. widening a batting stance) would require very little relearning. I have had difficulty finding any references to support this statement.

    Zanone and Kelso (1992) write that a pre-existing movement pattern rather than the learning of a new skill would meet behavioral demands of a modified task.

    Can someone point me in the direction of research that has shown stability of a movement pattern following minor variations in task alteration? or any other research that may assist me.

    Clara Soper
    PhD Candidate
    School of Community Health and Sport Studies
    Auckland University of Technology
    Private Bag 92006
    Auckland, New Zealand
    Tel: (+649) 917 9999 xtn 7848
    Fax: (+649) 917 9960

    "To realize one's destiny is a person's only obligation."
    -- from The Alchemist

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