Only when I moved away from the US did I realize how there really is such a thing as an American psyche and that I was so American. Or maybe it is Californian, as that was the only thing I knew. When I was in California, I was just entrenched in the huge spectrum of personalities, characters, walks of life, shapes and shades of souls that I couldn't see the common thread other than in time and space (and even that is questionable and confined to only the apparent physical).
How I would describe the American psyche -- for all non-American, don't laugh because all things are relative. We were brought up to be so critical of American culture, for not having a culture other than capitalism and being extremely critical of our system. With a bit of distance and more means of comparison, I see that, yes, it is so immensely far from being perfect and things could be much improved and brought to par with, say, the more socialist European governments -- but actually, the US does many things actually quite well in comparison to elsewhere. So the American (or Californian) psyche -- open and relatively critically minded (remember that the entire country was flooded by wanderers fleeing from the status quo back home -- and yes, true, collective memory is very short-lived, but the spirit, I think remains because there is still less of a solid social status quo to anchor onto compared to the Old World) , undeterred by the same degree of unknowns and height of obstacles that might deter others (and hence the seemingly constantly "cheery-ness", which is not the same as happiness, leading to the false interpretation that Americans are superficial because no one can be so happy and chirpy all the time for real) -- so all in all you have a state of doers. You ask why there are differences but do not judge them until you see why.
Political Satire
Daily Show
Tonight Tomorrow
* Some weekly campus humor: The Heuristic Squelch
* More weekly humor (political satire): The Onion
Radio stations
Anything NPR!