Dissociation of grip/load-force coupling during a bimanual manipulative assignment

The aim of the present study was to examine interlimb interactions of grasp ing forces during a bimanual manipulative assignment that required the exec ution of a drawer-opening task with the left hand and an object-holding tas k with the right hand. Compared with the unimanual performance, the grip/lo ad-force ratio of the object-holding task was shifted towards that of the s imultaneously executed drawer-opening task. This shows that force parameter ization of the dynamic activity interacted with that of the static activity . That the increased force ratio only involved modification of grip force, while load force was held constant, indicates a disruption of the commonly observed co-variation of both forces during a manipulative action. These da ta are consistent with the notion that the coordinative constraint between grip and load force is a flexible parameter.