Perceptual‐cognitive control of bimanual coordination

Abstract

The author proposes and investigates the hypothesis that spontaneous bimanual coordination phenomena arise at a perceptual‐cognitive level, with the relevant muscles automatically, flexibly, and effortlessly tuned in service to perceptible movement properties. It has often been held that the powerful symmetry tendency in bimanual coordination originates at a motor command level. New evidence suggests that, at least in some paradigms, the symmetry tendency is actually a bias towards perceptible symmetry and seems thus directly and solely to be governed by a purely perceptual‐cognitive control principle. It is argued that this proposal extends to spontaneous bimanual coordination phenomena in general, whether that symmetry is the guiding principle, or whether a powerful role of perceptual and conceptual grouping principles other than symmetry are plausible. Neuronal wiring and biomechanical factors may influence the preferred coordination mode by way of their perceptible consequences. Interestingly, bodily bimanual interference can virtually vanish if the movement goal is suitably defined. In this case, interference is defined with regard to these movement targets or objects to‐be‐manipulated. The organizational costs of a given movement seem to be independent of the bodily action as such, but rather dependent on how the whole movement is strategically conceived and represented as a perceptible event in its environment. An effective representation can often be organized in a surprisingly sparse and economic way. In particular, a detailed and complete parameterization of the bodily movement is not necessary. Even bodily movements that are impossible to perform when instructed as such may be performed with ease if a simple perceptual cognitive reference structure for control can be conceived. In conclusion, I propose the hypothesis that simple bimanual coordination is entirely guided and controlled by the perceptual‐cognitive system. Moreover, a perceptual‐cognitive approach seems most promising as a unifying perspective for understanding voluntary movements of all kinds at all levels of organization.