With me, it seems that I get new obsessions fairly often, but the old ones never really leave. I still really like them, they just aren't an obsession. (Well, not an Aspie obsession- still more of an obsession than a neurotypical's "obsession.") My mind gets cluttered but never is emptied.
My intensity of the obsession waxes and wanes, just like my OCD obsessions. Some days I barely think about it, and on other days, I try to slip the topic into conversation any way I know how. I'm very giddy when I'm having a day where I need to talk and talk about my obsession. And, on those days, it is all-consuming. I can't focus on anything else. But, for the most part, I can function and get my work done. I've always had more than one at a time. I honestly don't think I've ever just had one "special interest" at a time. Now, I only ever have one "special interest" that I need to talk and talk about, so maybe that's what you mean. (I can tell when an Aspie obsession cools off when I don't have the compulsion to talk and talk about it.) I have had both broad and specific obsessions, but mine are usually specific. Like, as a kid, I was obsessed with road signs and height requirements for amusement park rides. (Still love both, but the road signs aren't an obsession any more. The height requirements are, though, and if I go to an amusement park, learning those is as much fun to me as the actual ride.) I wasn't interested in cars or transportation- just the signs. My main obsession now is A Beautiful Mind, but that's specific, too. I'm not obsessed with movies/cinema, in general. The only "broad" obsession I have is biochemistry/anatomy/neuropsych. Just science. And American history, too. But for things that aren't science/history-related, my obsessions are pretty focused. Even within my science/history obsessions, I have focuses. Like the 1920's and cellular respiration.
-OddDuckNash4348-
_________________
Helinger: Now, what do you see, John?
Nash: Recognition...
Helinger: Well, try seeing accomplishment!
Nash: Is there a difference?