Deanna Kennedy, M.S.
Coordinating movements between the limbs is important for many activities of daily living and sport specific skills. Buttoning your shirt, opening a bottle, driving your car, and serving a tennis ball are tasks that involve some type of coordination between the limbs. Although these examples of bimanual movements are relatively easy for most individuals to produce, other more complex coordination patterns have proved to be quite difficult. Bimanual tasks like playing the piano or guitar, for example, underscore the difficulty that can be associated with complex bimanual coordination patterns.
The traditional view is that the difficulty in producing complex bimanual coordination patterns is related to neuromuscular constraints. That is, we have an inherent tendency to produce the same movement in time with each limb. To illustrate this tendency, try tapping each hand on a table in an alternating fashion. Easy? Speed up your tempo. When you do so, there will come a point in which you begin to tap each hand together.
More recent research, however, has pointed toward perceptual and attentional factors imposed by the testing environment to explain the difficulty with complex bimanual coordination patterns. For example, Mechsner and colleagues demonstrated that a 4:3 polyrhythm could be performed relatively well when the perceptual information was manipulated to establish perceptual symmetry. Participants were required to move two visible flags by turning levers hidden under the table. The gears for one flag were set at 1:1 so that each full turn of the lever resulted in one full circle of that flag while the gears for the second flag were set at 4:3 requiring a ¾ turn of the lever to produce one full revolution of that flag. The participants were told to turn both flags together. It took participants approximately 20 minutes to do so. It is important to note, that this flag pattern actually produced a 4:3 bimanual coordination pattern, a complex pattern that was once thought difficult or near impossible to perform without extensive practice.
Another perceptual manipulation involves the use of Lissajous plots. Lissajous plots integrate the position of the two limbs into a single point, much like a video game. For example, one limb may control up and down movement of a cursor while the other limb controls back and forth movement of the same cursor. When provided this type of integrated feedback and other distractions are reduced, individuals can effectively perform a variety of complex bimanual coordination patterns that were once thought difficult or near impossible to perform, within a few minutes of practice.
The use of Lissajous plots allow for the successful performance of complex bimanual tasks because the integrated information reduces attentional demands by allocating attentional focus to a single point rather than splitting attention between the two limbs and provides information to guide the participants performance. In fact, when provided this type of integrated perceptual information, performing complex coordination tasks can be as easy as following the yellow brick road from Munchkinland to the Emerald City.
For Further Reading:
- Kovacs AJ, Buchanan JJ, Shea CH (2010). Impossible is nothing: 5:3 and 4:3 multi-frequency bimanual coordination. Experimental Brain Research, 201, 249-259.http://download.springer.com/static/pdf/397/art%253A10.1007%252Fs00221-009-2031-y.pdf?auth66=1403292514_fa62854051fdecf23b87f7487ce6b167&ext=.pdf
- Mechsner F, Kerzel D, Knoblich G, & Prinz W. (2001). Perceptual basis of bimanual coordination. Nature, 414, 69-73. http://www.nature.com/nature/journal/v414/n6859/pdf/414069a0.pdf
- Wang C, Kennedy DM, Boyle JB, & Shea, CH (1995). A guide to performing difficult bimanual coordination task: just follow the yellow brick road. Experimental Brain Research, 230, 31-40. http://download.springer.com/static/pdf/320/art%253A10.1007%252Fs00221-013-3628-8.pdf?auth66=1403292601_19652764dec5ecb1f60daa14676b9fa9&ext=.pdf