Movement-Sequence Observation in Healthy Adults: Motor and Cognitive Effects on Effector-Independent Performance

Studies examining the effects of action observation (AO) on ipsilateral versus contralateral upper limb (UL) motor performance have reported mixed findings. Furthermore, the extent to which the cognitive component of sequence observation contributes to AO-related improvements in motor sequence execution remains unclear. The investigators aimed to determine whether observing unilateral UL reaching movement (RM) sequences affects UL RM performance in an effector-dependent or effector-independent manner in healthy adults and to determine the contribution of the cognitive aspect, particularly sequence memory, to the motor performance. Sixty participants randomly participated in a single-session intervention of (1) observing RM sequences with the non-dominant left UL (AO group); or (2) observing identical light switches sequences (SO group); or (3) observing nature films (Nature Observation (NO) group). Sequential RMs of both the left and right ULs (ipsilateral and contralateral to the observed movements, respectively) toward the light switches were tested before and immediately after the intervention, and retested after 24 h.