Monday 24 October 2011

The learning of 90° continuous relative phase with and without Lissajous feedback: External and internally generated bimanual coordination

The primary aim of this experiment was to find out if reducing the amount of lissajous feedback would allow participants to develop an internal representation of the coordinated pattern, enabling them to effectively perform bimanual coordination tasks without any feedback.

Participants were randomly assigned to one of nine groups that differed in terms of the percent of time they received Lissajous feedback (100%, 50% or 0%). For the 50% feedback group Lissajous feedback was presented in a fading schedule (25–25–20–20– 15–15–10–10–5–5 s) for each consecutive trial. The feedback was provided at the beginning of each trial and withdrawn according to the schedule above.


Apriori comparisons indicated that after 5 minutes of practice, participants who received 50% feedback had considerably higher RMSE values on the no-Lissajous test compared with participants who received 100% feedback, t(12)=4.63, pb.05, on the Lissajous test. After 20 minutes of practice, participants who received 50% feedback performed just as well as the group who had received 100% feedback in a test with no Lissajous feedback.


More practice while receiving 100% Lissajous feedback did not help participants to develop an internal representation of the task or improve their ability to perform when the Lissajous feedback was present. On practice trials while receiving 50% Lissajous feedback participants seek out and process other sources of information necessary to perform the task. This could result in participants acquiring the capability to detect and correct errors. The result is improved performance on tests without extrinsic feedback.

5 comments:

  1. What is the Apriori comparison?

    Also when using the Lissajous Feedback was this with or without the permanent trace of the target relative phase present?

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  2. The apriori comparison was relative phase RMSE between participants receiving 50% feedback during acquisition on the no-Lissajous test and participants receiving 100% feedback during acquisition on the Lissajous test. These were compared using a t-test.
    Also Jack I’m not 100% sure about your second question, I found this bit of text in the article:

    “The Lissajous feedback was in the form of a cursor representing the joint position of the two limbs overlaid on a Lissajous template depicting the required phase relation between the limbs”

    Is that what you meant?

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  3. Yes thank you, the quote answers the question.
    I asked because in some papers the template shape in a Lissajous figure is classed as augmented feedback and in other papers it is classed as normal feedback. So I wanted to get it clear in my head what this study actually used in terms of Lissajous feedback.

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  4. How did the authors identify whether the learners had formed an internal representation of the task? Why do they think you need this representation?

    Some minor notes:

    Add a reference in APA format to the paper you're reviewing.

    What is RMSE? What is it measuring?

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  5. To identify whether the learners had formed an internal representation of the task they compared relative phase error and variability on delayed tests with and without feedback after various amounts of practice.
    The participants who practiced with reduced frequency feedback improved their performance considerably on the delayed no feedback test. After 20 minutes of practice, they were producing comparable results on relative phase errors and variability on the no-feedback test to the participants in the 100% feedback group on the feedback test.
    They say it’s important to not become dependent on the lissajous feedback because if you do, you only learn how to respond to that stimulus and it can block participants from processing other intrinsic information necessary for acquiring an internal representation of the test. The reduced feedback frequency forces participants to seek out and process other sources of information. This gives the participant the capability to detect and correct errors without feedback being provided.

    RMSE stands for Root Mean Square Error and it was used to measure the degree in which the goal relative phase was achieved e.g. 90 degrees.

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