Figure 9. Effects of increasing task difficulty on the speed and timing of the reach by priming the final desired orientation such as to evoke complex mental rotation of the stimulus.
(A) PD1 patients moved significantly slower than PD2 patients (median 0.65 m/s vs. 1.15 m/s, χ2 215.05, p<10− 48) according to the values of the hand’s maximum speed returning from the target to the resting position. (B) The timing of the maximum speed was not significantly different in the two patient groups (median 0.52 s, χ2 2.86, p>0.1) but both groups took longer to reach the velocity peak than NC’s did (median 0.35 s, χ2 123.5, p<10− 27).