We had taught capuchin monkeys to reach a cup of food on a tray by pulling on a bar attached to the tray.

• 在那里，我们训练卡布钦猴（capuchinmonkey，译注：一种新世界猴）合作取食。放食物的杯子摆在笼子外面一个可移动的托盘上，托盘连著一根拉杆，伸进猴子笼里。