Venting when angry leads to less happiness after the initial catharsis.
In romantic relationships, similar personalities attract, rather than opposites.
The blog Barking up the Wrong Tree also collects psychology experiments of this kind. The posts are often based on single studies, so I don't know how well-established they are, but it's often possible to reverse the result and invent a plausible explanation. Some examples:
Spending money on other people makes you happier than spending it on yourself
Heavy TV-watchers are less happy when given more channel options (which itself is an example of the general finding that having a large number of choices reduces happiness)
Chronically ill patients may be less happier if they hope for a cure
I don't think these are exactly what Eliezer is looking for - these are statements that go against our natural inclinations, whereas I think Eliezer is looking like things that are (as someone said) "obviously correct in both directions", i.e. stuff we could rationalize as true either way upon encountering it.
I'm writing the section of the rationality book dealing with hindsight bias, and I'd like to write my own, less racially charged and less America-specific, version of the Hindsight Devalues Science example - in the original, facts like "Better educated soldiers suffered more adjustment problems than less educated soldiers. (Intellectuals were less prepared for battle stresses than street-smart people.)" which is actually an inverted version of the truth, that still sounds plausible enough that people will try to explain it even though it's wrong.
I'm looking for facts that are experimentally verified and invertible, i.e., I can give five examples that are the opposite of the usual results without people catching on.
Divia (today's writing assistant) has suggested facts about marriage and facts about happiness as possible sources of examples, but neither of us can think of a good set of facts offhand and Googling didn't help me much. Five related facts would be nice, but failing that I'll just take five facts. My own brain just seems to be very bad at answering this kind of query for some reason; I literally can't think of five things I know.
(Note also that I have a general policy of keeping anything related to religion out of the rationality book - that there be no mention of it whatsoever.)