Implicit learning of a perceptual-motor skill after stroke.

BACKGROUND AND PURPOSE A motor skill can be learned implicitly, without awareness of what is being learned. The purpose of this study was to examine the ability of adults who had unilateral stroke to learn implicitly a perceptual-motor task. SUBJECTS Subjects were 47 people who were poststroke and 36 control subjects. METHODS Participants performed sequences of hand movements in response to target lights in 2 conditions: a patterned sequence and a random sequence. Participants were not given explicit knowledge of the presence of the 2 conditions. Those who had stroke performed with the upper-extremity ipsilateral to the lesion. RESULTS Subjects who had stroke performed more slowly than control subjects. For both groups, times decreased with practice of the patterned sequence, increased with introduction of the random sequence, and decreased again with reintroduction of the patterned sequence. Group differences persisted in a retention test given the next day of the patterned sequence, and both groups showed decreased times over the course of the retention test. DISCUSSION AND CONCLUSION People with stroke are able to learn a perceptual-motor task even without explicit instructions regarding the patterned sequence embedded in the task.