There's sort of a period around the age of four, four and a half, where kids make the transition from failure to success.

儿童在大约四岁四岁半时,会发生从失败向成功的转变

耶鲁公开课 - 心理学导论课程节选

You start off with a transition period when you're falling asleep. We call that stage I.

一开始是过渡期,你开始进入睡眠状态，这是第一阶段。

耶鲁公开课 - 心理学导论课程节选