The first time I heard that the 60s were forty years ago, I literally counted the decades off on my fingers because I couldn't believe it. Yes, I know it's more like fifty years now, but I'm used to it.
I don't know if some periods of pop-cultural history are simply more remarkable than others and thus leave more vivid memories, or it just comes from aging. I am 37 and everything post-2000 is a blur. I don't think I could name more than one popular song esp. one I liked that was released after 2000. To me the difference between 1992 and 1996 was huge, such as techno-house went from underground to mainstream and transformed the whole musical landscape, 2000 to 2010 is like, meh, some hipster bands got more popular than some other hipster bands?...
There's a lot of background mess in our mental pictures of the world. We try and be accurate on important issues, but a whole lot of the less important stuff we pick up from the media, the movies, and random impressions. And once these impressions are in our mental pictures, they just don't go away - until we find a fact that causes us to say "huh", and reassess.
Here are three facts that have caused that "huh" in me, recently, and completely rearranged minor parts of my mental map. I'm sharing them here, because that experience is a valuable one.