Do monkeys choose the more skillful hand in manual problem-solving?

To investigate the relationship between manual skills and hand preference in 4 female Japanese monkeys (Macaca fuscata), the technique of concurrent investigation of manual skills and hand preference was introduced. 4 female Japanese monkeys were required to take food out of a pipe using the left hand and right hand alternately. The performance time and the number of deviations from alternate sequence were recorded as measure of manual skills and hand preference. In the result, the preferred hand was not always consistently the skillful one; however, only one subject tended to choose the more skillful hand in problem-solving, and another subject learned the alternate sequence of reaching. The performances of two subjects indicated discrimination of both hands in Japanese monkeys is possible.