I'm going to go break my own rule about trying to avoid talking about stuff I don't know anything about now, although judging from previous posts, I won't be alone, unless the entire forum is composed of MIT professors.
I recently read Flatland, and if you're talking about a 4th visual spatial dimension then it's quite possible that it is there (along with any number of other visual spatial dimensions). The 4th dimension is perpendicular to the 3rd dimension. We either don't have the eyes built to see them, the brains that can interpret them, we're not in the right place to observe them or our universe is just not built that way.
However, you should still consult your nearest trans-dimensional being for further guidance. Baring that, walking up 4 dimensional staircase or staring at an Escher painting long enough should suffice. Consuming hallucinogenic drugs (in the name of science of course) may accelerate the process. If you're really desperate you could try emailing a mathematician who is focused in the field.
EDIT: changed visual to spatial (forget you snackbar)