Second sight, or the ability to get glimpses of information from the spirit world, or next world, or ethereal, is often associated with Celtic peoples, such as the Irish, Welsh, Britons, and the like. It may well be an attribute of other peoples, such as American Indians, but I don't know as much about those groups.
Anyway, I think it's likely that those who can see what Dorothy sees likely have a measure of second sight.
I've also heard a variation of this called paroptic vision, which I suspect is much the same. I believe new age thought holds that paroptic vision sees into the ethereal/astral/whathaveyou by use of the third eye/pineal gland. I think it's more likely that paroptic vision, the ability to see the otherwise invisible world and its inhabitants, is tied to the minds eye and imagination.
Bhuddists hold that the imagination is a sense, just like the other five senses. The imagination, which I think is tied with the conscious, is tied with our ability to visualize and "make things up," but that does not mean that all imaginary things are made up. Indeed, some are quite real, and independant of us.
I'll stop. This post is long enough.