Moving effortlessly in three dimensions: does Donders' law apply to arm movement?

Abstract

Donders' law, as applied to the arm, predicts that to every location of the hand in space there corresponds a unique posture of the arm as defined by shoulder and elbow angles. This prediction was tested experimentally by asking human subjects to make pointing movements to a select number of target locations starting from a wide range of initial hand locations. The posture of the arm was measured at the start and end of every movement by means of video cameras. It was found that, in general, the posture of the arm at a given hand location does depend on the starting location of the movement and that, consequently, Donders' law is violated in this experimental condition. Kinematic and kinetic factors that could account for the variations in arm posture were investigated. It proved impossible to predict the final posture of the arm purely from kinematics, based on the initial posture of the arm. One hypothesis was successful in predicting final arm postures, namely that the final posture minimizes the amount of work that must be done to transport the arm from the starting location.

Getting a grip: different actions and visual guidance of the thumb and finger in precision grasping

“…From this we calculated the amplitude of maximal lateral deviation (LatDev max ) of the thumb and the finger on each movement, with positive values representing rightward deviations. Taking the shortest Euclidean path (i.e., with zero deviation) in moving each digit from its start to end positions can be considered 'ideal' with respect to optimizing energetic costs (Soechting et al 1995).…”

Computational approaches to motor control

“…Although a fully extended arm obeys this law [51], there are some minor violations for armpointing movements, involving both shoulder and forearm rotations [52]. For unexpected target shifts, the final arm posture is neither more variable nor different from the one in the absence of such a shift [53], and can be accounted for by a model involving the minimization of kinetic energy [52]. Different forms of Donder's law apply to the upper and lower arm during pointing [54•].…”

Posture-based or trajectory-based movement planning: a comparison of direct and indirect pointing movements

“…Various models have been proposed to explain the plan ning and execution of arm movements (Feldman & Levin, 1995;Gielen, Vrijenhoek, Flash, & Neggers, 1997;Harris & Wolpert, 1998;Soechting, Buneo, Herrmann, & Flanders, 1995;Rosenbaum, Loukopoulos, Meulenbroek, Vaughan, & Engelbrecht, 1995;Rosenbaum, Meulenbroek, Jansen, & Vaughan, 2001;Uno, Kawato, & Suzuki, 1989). These mod els can be classified into two categories.…”

“…The final posture of the arm results from the selected trajectory. Examples of models within the trajectory-based category are the minimum-work model (Soechting et al, 1995), the minimum torque-change model (Uno et al, 1989), and the minimum-variance model (Harris & Wolpert, 1998). The knowledge model to postu late a new model to account for the cure of Rosenbaum et al, (1995Rosenbaum et al, ( , 2001) is a special case within this classification scheme.…”

“…Soechting et al (1995) compared the predictions of Donders' law and the minimum-work hypothesis with experimental data. In 3 Sentence added to clarify point by Reviewer 2 their study participants were instructed to point towards tar gets starting from different positions in 3-D space.…”