HOW IS BODY ORIENTATION CONTROLLED DURING SOMERSAULTING

How body orientation is controlled during somersaulting was investigat ed in 2 experiments that analyzed the kinematics of 223 backward stand ing somersaults. In Experiment 1, open-loop, initial-condition (flight duration), and prospective (time to contact, or TC1) control strategi es were tested as candidates for the regulation of body moment of iner tia during the jump. Decreasing between-trials variability of body ori entation over time as well as a negative correlation between body angu lar velocity and TC1 suggested that the moment of inertia was regulate d prospectively. In Experiment 2, the visual basis for this regulation was examined by asking experts and novices to execute somersaults eit her with eyes closed or open. Results showed that the prospective regu lation observed in the vision condition disappeared in the no-vision c ondition with the experts, arguing in favor of a visual control during the jump. Such a coupling was absent with the novices, thus illustrat ing the role played by the perception-action cycle in the learning pro cess.