  First, surprise does not require uncertainty, although it might first appear otherwise. If I think that something will happen and it does,  then I will not feel surprise. For example, if I think that my  friends have gathered at my apartment for my birthday, I will not  feel surprise when I come home and find them in my living room. Based on failed surprise parties, one may conclude that surprise requires  uncertainty. But this is too hasty. Surprise does not require that we be in a cognitive state of uncertainty. And it is fairly easy to see  why. I may be certain that my beer sits on the table in front of me,  but if it disappears when I reach for it, I will be surprised. Hence, I can feel surprise without uncertainty. To be mistaken is not the  same as to be uncertain. Surprise results from the sudden subversion  of an expectation, not the resolution of cognitive uncertainty. 