Hello, everyone. I feel that I have taken an unusually circuitous route to becoming a rationalist. I started out close to rationalism in ideaspace, went really far, and then came all of the way back. I have to begin by saying how rationalism was 'epistemically proximal' to my early beliefs. After that, I'll show how far I went. Then, I'll show how I came back.
I think it can be said that my intellectual influences have been relatively epistemically favorable. I think it all started with the film adaptation of Jurassic Park when I was a kid; I think that it made me find joy in the merely real. If dinosaurs are that awesome, and they were dead and science brought them back, then science must be awesome! Then I became interested in outer space and all of the other things that kids automatically love when they love science. When I was older, like many others, I sometimes felt the urge to write science fiction. If I remember correctly, I was researching terraforming for one story, and then I came across a Wikipedia reference to Robert Freitas' respective estimations for how long it would take biological organisms and nanotechnological machines to sequester all of the carbon dioxide in the Venusian atmosphere. That led me to his book Xenology. Therein, he discussed various alternative forms of government that alien civilizations might use, and mentioned Robin Hanson's work on idea futures/prediction markets, proposing a form of government based on prediction markets called "futarchy." I didn't follow the Wikipedia page to Overcoming Bias, which really sucks because I think that this was right around the time that Eliezer was still posting on OB what later became the sequences, or around the time that LW was coming about.
Later, I got into lifehacks like mnemonics and speed reading and stuff, and I found the list of the best textbooks on every subject. I still didn't become a user or even a lurker.
Then, less great things happened.
I became an intellectual contrarian and decided that people hadn't 'given enough credit' to psychodynamic psychology and the historical contributions of psychoanalysis. It didn't help that there were people supporting this who are Nobel laureates and have written leading texts in the field of neuroscience, or that a lot of people are trying to shoehorn Freud's theories into neuroscience. Then I became a meta-contrarian and decided that Lacan was, as Prof. Chomsky would put it, a conscious charlatan, but that Sartre was alright. Then Sartre got me into existentialism, and existentialism got me into continental 'philosophy' in general. I decided that analytic philosophy (read: philosophy) and science were imposing themselves upon a domain in which they did not belong.
During this time, my friend, who is a huge Harry Potter fan, showed me Harry Potter and the Methods of Rationality. I was like, "That's cool," and didn't read it.
For a reason that I can't remember, I ended up looking up the textbook list again a few days ago, and, fortunately, I thought: "This is my fifth time here in as many years and I haven't seen what they have to say. Maybe I should give it a shot." And then LW convinced the everloving hell out of me.
To break up the awkward silence at the start of a recent Overcoming Bias meetup, I asked everyone present to tell their rationalist origin story - a key event or fact that played a role in their first beginning to aspire to rationality. This worked surprisingly well (and I would recommend it for future meetups).
I think I've already told enough of my own origin story on Overcoming Bias: how I was digging in my parents' yard as a kid and found a tarnished silver amulet inscribed with Bayes's Theorem, and how I wore it to bed that night and dreamed of a woman in white, holding an ancient leather-bound book called Judgment Under Uncertainty: Heuristics and Biases (eds. D. Kahneman, P. Slovic, and A. Tversky, 1982)... but there's no need to go into that again.
So, seriously... how did you originally go down that road?
Added: For some odd reason, many of the commenters here seem to have had a single experience in common - namely, at some point, encountering Overcoming Bias... But I'm especially interested in what it takes to get the transition started - crossing the first divide. This would be very valuable knowledge if it can be generalized. If that did happen at OB, please try to specify what was the crucial "Aha!" insight (down to the specific post if possible).