Some people can play chess blindfolded. There is a popular method of memorizing which has one visualize the placement of objects in a familiar space. Both of these seem absurd to me, as I can at best conjure a fleeting glimpse of an object in greyscale. When I calculate chess tactics I do so in a manner which seems almost kinesthetic, as if I’m feeling the movements of the pieces, and I have to look at the board while I do it. When I memorize things, like poems or the digits of pi, I just repeat them until each element of the sequence magically evokes the next. There is no visualization.