translation.en: Even more remarkably though, the fact that 15 month-olds didn't do this suggests that these 18 month-olds had learned this deep, profound fact about human nature in the three months from when they were 15 months old.
translation.zh: 但更让人值得关注的是， 15个月大的宝宝们没有这种意识 说明18月大的懂得了 一个人性的奥秘 而当他们3个月前还没有意识到。