The scaling of human grip configurations.

The many degrees of freedom of the hand and arm afford the wide range and rich adaptability of human grip configurations in action. Several classification schemes of human grip configurations have been proposed, but none is based on scaling laws of physical biology, which are well established for other categorizations of fundamental physical activities such as locomotion. This study examined the preferred human grip configurations used to displace to a new location cubes that varied systematically in length (L), mass (M), and density (ML-3). The body-scaled equation K = log L + (log M)/h (where h refers to anthropometric measures of the hand) predicted the grip configurations used to displace objects. The findings suggest that information about the dynamic scaling relation is picked up visually and organizes the many degrees of freedom of the hand-arm complex in the coordination of prehensile grip configurations.