ReadOasis Step 3

Professor Harry Harlow thought that he had created a difficult puzzle. He placed a hinge on a block of wood. A hook held the hinge closed. A pin blocked the movement of the hook. To open the hinge you first had to remove the pin, then swing the hook around. It looked simple enough, but the puzzle wasn?t meant for a person. He and his researchers planned to give the puzzle to eight rhesus monkeys. Harlow put the puzzle in the cage and watched what happened.

Within days ...