(A) GEMs for two different reaching tasks
(Dn/Tn = c and
DnTn = c), with typical data from
one subject. (B) Experimental normalized standard deviations for
all subjects, for each task after Day 1 and Day 2 of practice, for tangential
(δT) and perpendicular
(δP) deviations from each GEM. For
both tasks, subjects exhibited significantly greater variance in
δT than for
δP. However, this effect was more
pronounced for the D/T task (p <
0:0005) than for the DT task (p = 0:019).
(C) Stability multipliers (λ) for all
subjects estimated for each task after Day 1 and Day 2 of practice, for
δT and
δP deviations from each GEM. Subjects
exhibited significantly higher stability (smaller λ) for goal-relevant
δP fluctuations than for
goal-equivalent λT fluctuations for both
tasks (p < 0:0005). However, in contrast to the variability results
(B), these effects were slightly more pronounced for the
DT task than for the D/T task (adapted
from Smallwood et al., 2012). All error
bars indicate between-subject ±95% confidence intervals.