Objective: The motor skill performance and learning in older adults are of a great importance. The primary purpose of this study was to determine whether older adult’s explicit knowledge effect on implicit learning and motor performance and which are typical for rehabilitation and skills acquired in older adults.

Materials & Methods: In this comparative study a serial reaction time task by using software was applied for studying implicit and explicit motor learning in 15 older adults received intentional and 15 older adults received incidental instruction in a randomly chosen. In this task 4 squares with different colors appeared on the monitor and subjects were asked to press its defined key immediately after observing it. In the first day subjects practiced 8 motor blocks (4 patterned blocks, then 2 random blocks and finally 2 patterned blocks). Two next day subjects practiced a retention test consisted of 2 patterned blocks. Implicit group were not provided with any explanation about the sequence of squares and explicit group receive explanation about the sequence of squares and blocks. All subjects were right handed and no history of neurologic disease or musculoskeletal dysfunction. Date was analyzed by Independent T test and ANOVA.

Results: The results indicated that Block time differences of second block with eight and tenth blocks (two next days) were significant and similar in both groups. Final stage of Task (7-10 blocks) was significant slower in explicit than implicit groups that show significant higher learning in implicit groups but no difference in performance improvement with explicit groups (P<0.001).

Conclusion: High motor learning (defined as stable decrease of block times) in implicit older adults group shows explicit knowledge was enabled negative effects on implicit learning, although implicit and explicit groups wasn’t significant difference performance.