Persistence of primate hand preference despite initial training to the contrary.

Forty-six stumptail monkeys were tested for hand preference on a simple reaching task. Initial repeated reaches with the hand chosen for the first reach went unrewarded. All reaches following and including the earliest reach with the opposite hand were rewarded and were used to calculate overall hand preference for the task. A significant majority of the animals continued to prefer the hand initially used in unrewarded trials rather than the hand first receiving a reward. These results suggest that monkeys are predisposed to choose the hand preferred for a new task.