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

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Or even just funny things, like if somebody put like "Hammertime" on a stop sign.

或者，有趣的是，好像有人把“哈姆时间”（美国真人秀）画在停车标志牌上。

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