Well, put a pretty face here, an ugly face here, see if the baby prefers to look at the pretty one.

在这边放一张漂亮的脸庞,在这边放一张丑陋的脸庞,观察婴儿是否更喜欢注视漂亮的那个

耶鲁公开课 - 心理学导论课程节选

If the baby really sees it as different, the baby will look longer, and you could use that as a measure of what babies find different.

如果婴儿认为此物与之前出现物体不同,婴儿的注视时间会变长,你可以将注视时间变长,视为婴儿发现物体间区别的一种标志

耶鲁公开课 - 心理学导论课程节选

If they all look the same to the baby, the baby will just continue to tune out, but if the red looks different the baby will perk up.

如果对于婴儿来说,两种颜色没有差别,他就仍然不予理会,但如果他觉得红色与绿色不同,那他就会重新活跃起来

耶鲁公开课 - 心理学导论课程节选