FIGURE 2.
Experimental protocol. (A) A diagram of the four sessions. Following the practice, each session consisted of a series of five blocks: (1) baseline/wash-up, (2) learning, (3) half-force estimation task, (4) half-position estimation task, (5) half-force estimation task, and then questionnaire periods. The baseline/wash-up employed the half-linear condition. Then, one of three types of stiffness profiles (linear, quadratic, logarithmic) was assigned pseudo-randomly after the baseline/wash-up. (B) A cartoon illustrating the repetitive movements to reach the target (Z = 12 cm, Fz = 30 kg⋅m/s2) and a test trial.