Signatures of contextual interference in implicit sensorimotor adaptation

Contextual interference refers to the phenomenon whereby a blocked
practice schedule results in faster acquisition but poorer retention of
new motor skills compared to a random practice schedule. While contextual
interference has been observed under a broad range of tasks, it remains
unclear if this effect generalizes to the implicit and automatic
recalibration of an overlearned motor skill. To address this question, we
compared blocked and random practice schedules on a reaching task in which
we used a feedback perturbation method that isolates implicit adaptation.
The degree of implicit adaptation was quantified as the change in hand
angle in the opposite direction of the perturbation, and retention was
quantified as the percent of adaptation remaining after visual feedback
was extinguished. In two experiments, participants tested under a random
practice schedule exhibited slower implicit adaptation, but better
retention compared to participants tested under a blocked practice
schedule, the signature of contextual interference. These results indicate
that contextual interference is not limited to the acquisition of new
motor skills but also applies to the implicit adaptation of established
motor skills.