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.
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.