In all plots, gray, blue, and red represent the control, acquired, and congenital groups, respectively. (A) Left: rose plot density histogram of the distribution of bias angles across the groups, the larger the arc the more individuals from that groups had a bias within the arcs angle range. We found no significant differences in bias angle between the groups (Watson-Williams circular test: F(2,48)=1.95, p=0.15). Right: Error bias and noise results. No significant group differences were found for bias (F(2,47)=2.40, p=0.1, BFIncl=0.72). The congenital group shows significantly more motor noise than amputees and controls (F(2,47)=14.15, p<0.001, ηp2=0.38; post hoc significance levels are plotted). (B) Initial directional error results. The congenital group has larger directional error in the initial phase of reaching (F(2,47)=8.01, p<0.001, ηp2=0.26; post hoc significance levels are plotted). (C) 1D localization task results. Participants placed their residual limb or artificial arm inside an opaque tube and were asked to assess the location of the limb using their intact arm. We found no localization differences between the acquired and congenital groups in either condition (BF10<0.33 for both). The gray line next to the y-axis shows the mean ± s.e.m of control group’s nondominant hand localization errors. (D) 2D localization task results. Using the same apparatus, participants performed reaches to visual targets without receiving visual feedback during the reach. We found no group differences in absolute error (F(2,44)=0.71, p=0.5, BFIncl=0.33). (E) Relationship between artificial arm motor noise and age at first artificial arm use artificial arm in the congenital group. See Figure 2—figure supplement 1 for plots with individual participants’ data points. *p<0.05, **p<0.01, ***p<0.001.
© 2010, Wilson et al. Panel D is reproduced from Wilson et al., 2010, published under the Creative Commons Attribution 4.0 International Public License.