Figure 1.

Schematic view of the experimental setup. A, Experiment 1. The hand pad was located at 30 cm from the subject. The turntable randomly presented the objects 30 cm ahead from the hand pad. A screen, made from switchable transparent glass, was positioned between the subject and the turntable to control precisely the timing of object presentation. B, Experiment 2. Subjects had to grasp and lift a manipulandum with force sensors measuring the GF (red) and LF (blue). A hole under the table beneath the manipulandum contained a hollow steel cylinder. A load of 300 g was placed inside the cylinder and could be attached to the manipulandum to increase its weight without the subject being aware.