Perceptual basis of bimanual coordination

Abstract

Periodic bimanual movements are often the focus of studies of the basic organizational principles of human actions. In such movements there is a typical spontaneous tendency towards mirror symmetry. Even involuntary slips from asymmetrical movement patterns into symmetry occur, but not vice versa. Traditionally, this phenomenon has been interpreted as a tendency towards co-activation of homologous muscles, probably originating in motoric neuronal structures. Here we provide evidence contrary to this widespread assumption. We show for two prominent experimental models-bimanual finger oscillation and bimanual four-finger tapping-that the symmetry bias is actually towards spatial, perceptual symmetry, without regard to the muscles involved. We suggest that spontaneous coordination phenomena of this kind are purely perceptual in nature. In the case of a bimanual circling model, our findings reveal that highly complex, even 'impossible' movements can easily be performed with only simple visual feedback. A 'motoric' representation of the performed perceptual oscillation patterns is not necessary. Thus there is no need to translate such a 'motoric' into a 'perceptual' representation or vice versa, using 'internal models' (ref. 29). We suggest that voluntary movements are organized by way of a representation of the perceptual goals, whereas the corresponding motor activity, of sometimes high complexity, is spontaneously and flexibly tuned in.

Multilevel coordination stability: Integrated goal representations in simultaneous intra-personal and inter-agent coordination

“…Given that sequences of tones close in pitch are more likely to be perceived as a single stream than sequences of tones separated by large pitch differences (see Bregman, 1990), the results of Summers et al suggest that bimanual coordination is more stable when the two hands are controlled with reference to integrated rather than independent movement goals (also see Klapp, Hill, Tyler, Martin, Jagacinski, & Jones, 1985;Jagacinski, Marshburn, Klapp, & Jones, 1988;Summers, 2002). This phenomenon generalizes across tasks and modalities, as benefits of integrated goal representations have also been observed in studies addressing the influence of transformed visual feedback on the stability of intra-personal coordination (e.g., Bogaerts, Buekers, Zaal, & Swinnen, 2003;Mechsner, Kerzel, Knoblich, & Prinz, 2001) and inter-agent coordination (e.g., Roerdink, Peper, & Beek, 2005). …”

From visuo-motor interactions to imitation learning: Behavioural and brain imaging studies

“…One might expect that increased stability of a newly acquired coordination pattern, such as a particular phase relationship between two effectors in rhythmical actions, would be indicative of genuine motor involvement during observation, similar to effector dependence, consistency of timing, and force field adaptation as reviewed above. However, the studies by Mechsner and colleagues (Mechsner, Kerzel, Knoblich, & Prinz, 2001;Mechsner & Knoblich, 2004) on immediate visuomotor interactions during performance of bimanual tasks would caution against such an interpretation. These authors proposed a largely perceptual basis for bimanual coordination and suggested that not motor coordinative states but perceptual goals are the dominant organizing principle in inter-limb coordination.…”

Goal‐based representation in repetitive bimanual movements

“…If so, these results suggest that the complexity of the in-and anti-phase movement patterns are malleable, and under appropriate conditions, anti-phase movements may become "simpler" than in-phase movements (see also Kelso, 1995;Mechsner et al, 2001). …”

“…While much of this work has focused on biomechanical factors (e.g., activation of homologous muscles), recent studies have pointed to the importance of higher level variables such as attention (Pellecchia & Turvey, 2001) and goal-based representations (Fink et al, 2000;Mechsner et al, 2001). Defining what is meant by the term "goal" can be difficult.…”