translation.en: And the food is not important -- she does get a tiny reward, like one raisin for a correct response -- but she will do it for nothing, if you tell her beforehand.
translation.zh: 而且食物对她并不重要——她确实会得到一丁点儿的奖励， 比如每一次正确的反应，她会得到一颗葡萄干—— 但是你要是跟她事先讲明，没有食物她也心甘情愿。