Tuesday, 9 August 2011

Overloading the system in everyday life


When studying perception-action systems in motor control, coordinated rhythmic movements are frequently used. With difficulty in performing non-0° movements sometimes viewed as a bottleneck in the ability to control movement. Whereby the control of movement is overloaded and consequently successful performance is prevented. However during the study of coordinated rhythmic movements, the tasks employed are often simple and small scale movements. When in reality much more complicated movements are successfully performed frequently and by almost everyone.
To most if not all able bodied people the task of walking could not be considered in any way shape or form intimidating, complicated or challenging. Walking is simply done with very little conscious effort until something perturbs the usual rhythm of walking; such as the need to adapt gait for traversing steps, ice or many different changing terrains for example. However even under these altered conditions walking is rarely considered difficult and successful gait is achieved the vast majority of the time. Furthermore the number of muscles that must be controlled in the off-phase rhythm of walking is far in excess of that used when simply coordinating the movement of a joystick to some external timing source. Therefore it seems irrational to suggest that during simple coordinated rhythmic movements such as controlling a dot on a computer screen the motor control systems of the body become overloaded.
Furthermore on that basis, in typing this, the precise movements of each of my digits with the accuracy required to successfully type letters in specific sequences to construct words would be near impossible. However, despite the lack of a strictly rhythmic nature of the movement it is most certainly coordinated. Whereby the timing of each finger movement may potentially be considered as dictated by the accuracy and timing of the previous finger. Consequently for both novice and expert typers the movement of up to 10 digits in sync with each other should overload the system. However typing on a keyboard and walking have remarkably high success rates. Therefore begging the question, why?
The ability to perform both these tasks may lie in the availability and usefulness of the required feedback. Typing and walking success may be considered examples of successful feedback in line with work by Wilson and Colleagues. In which the use of feedback and changing feedback conditions yields differing movement stability. This may be present in typing as the appearance of the letters and words on the screen is effectively instantaneous feedback, where a comparison of desired movements may be compared to the appearance of a word be it spelt correctly or not; Therefore providing feedback about the movement of the digits used during typing.
References;
Wilson, A.D., W. Snapp-Childs., & G.P. Bingham. (2010). Perceptual Learning Immediately Yields New Stable Motor Coordination. Journal of Experimental Psychology: Human Perception and Performance. 36(6), 1508-1514.
Wilson, A.D., W. Snapp-Childs., R. Coats., & G.P. Bingham. (2010). Learning a Coordinated Rhythmic Movement With Task-appropriate Coordination Feedback. Experimental Brain Research. 205, 513-520.

2 comments:

  1. 1. Most of the sentences in the first paragraph are fragments; they don't make complete sentences on their own.

    2. The point of the first paragraph doesn't quite become clear until the end of the second. You're trying to describe the argument that some authors make, namely that performing non-0° movements is hard because it somehow overloads the control system (you should cite some work in the 'homologous muscle groups' approach here, that's where it comes from). This doesn't pop.

    The chain of events is about right, but you need to draw it all out some:
    Coordinated rhythmic movement is a commonly used task for studying perception-action.
    Non-0° movements are hard.
    This is sometimes attributed to an overload in the control system.
    However, the typical lab version of this task is very simple, so this overload idea seems weird.

    Then paragraph 2 is an example of a common non-0° movement that we do without much effort.

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  2. Furthermore on that basis, in typing this, the precise movements of each of my digits with the accuracy required to successfully type letters in specific sequences to construct words would be near impossible.
    A couple of things: you say 'on that basis' but it's not clear what 'that' refers to. After a while you need to remind people of these things. Second, this sentence is organised in a confusing manner. 'Impossibility' is what the sentence is about: get that information up front and centre in the sentence.

    Suggested edit along those lines:
    "A second example of a more complex coordinated action is typing. If the 'overload' suggestion was accurate, it should be impossible for me to perform the precise movements of each of my digits with the accuracy required to type letters in specific sequences."

    Don't over do the use of 'however' and 'furthermore' and 'whereby'. Students love these words for some reason I have never understood :)

    You can often got back to a sentence and get rid if it without losing the transition. So "However, despite the lack of a strictly rhythmic nature of the movement it is most certainly coordinated." can become "These movements, while not strictly rhythmic, are most certainly coordinated." The link to the previous sentence is the movements you're talking about, so again I've put them up front.

    "Therefore begging the question, why?"
    The question is actually 'how?'. I'd say it that way, too: "The question therefore remains, 'how do we do these movements?' This was again a sentence that was left hanging a bit.

    "...line with work by Wilson and Colleagues. In which the use of feedback..."
    edit to "...line with work by Wilson and colleagues, in which the use of feedback..."

    "...be it spelt correctly or not; Therefore providing feedback..."
    I like semi-colons, but you have to be a bit careful in how you use them. I'd make this two sentences, "...be it spelt correctly or not. This would then provide feedback...". Also I spell it 'spelled', but I think this is a UK/US thing. Lots of journals require US spelling, so just be aware of this.

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