ABSTRACT
When people repeat a movement many times, they typically reproduce a stereotyped pattern (Atkeson & Hollerbach, 1985). This stereotypy is one way that the motor system solves the degrees of freedom problem (Bernstein, 1967). We asked 3 subjects to make pointing movements in 8 conditions representing trajectories along the sides of a square (Figure 1A). The position of the index finger was measured, and resampled every centimeter. Spatial paths of 16 movements in Condition 1 from start (S) to target (T) are shown in Figure IB, and 16 movements in Condition 6 are shown in 1C. Although the paths are fairly similar, there is both extrinsic variation in where the movements are located in space, and also intrinsic variation in their shapes. The experimental apparatus, and movement patterns https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315799506/e3000455-006b-47f3-8dc3-986527b32979/content/fig67_1_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
