Beetle-sized (of the beautifully blue sort), at least.

Note also that the body the mind wears apparently (according to quirrel) does have an impact on the mind.

[...] Often I find that the best way to come up with new results is to find someone who's saying something that seems clearly, manifestly wrong to me, and then try to think of counterarguments. Wrong people provide a fertile source of research ideas.

-- Scott Aaronson, Quantum Computing Since Democritus (http://www.scottaaronson.com/democritus/lec14.html)

Can you say anything more substantive than that? It's plausible given the studies mentioned in Cialdini, an example of which follows:

Freedman and Fraser didn't stop there. They tried a slightly different procedure on another sample of homeowners. These people first received a request to sign a petition that favored "keeping California beautiful." Of course, nearly everyone signed since state beauty, like efficiency in government or sound prenatal care, is one of those issues no one opposes. After waiting about two weeks, Freedman and Eraser sent a new "volunteer worker" to these same homes to ask the residents to allow the big DRIVE CAREFULLY sign to be erected on their lawns. In some ways, the response of these homeowners was the most astounding of any in the study.

Approximately half of these people consented to the installation of the DRIVE CAREFULLY billboard, even though the small commitment they had made weeks earlier was not to driver safety but to an entirely different public-service topic, state beautification.

-- Robert Caildini, Influence: Science and Practice

I think you're leaving out another possibility: that they actually think they're right. This obviously doesn't apply to all cases, but I do think it's more common than you would think.

There's also a (related?) strong desire for consistency, which is explored in "Influence - Science and Practice" (Cialdini), which I found sheds some new light on the material in "How to win friends and influence people".

[Also, welcome to lesswrong]

And this sums up why I feel that respect for the silly beliefs of others is important: it sets the stage for the acceptable treatment of things that are confusing or silly.

It's not that you take the belief seriously, but rather that you take seriously the epistemic position that makes that belief seem sensible.

Oddly enough, the first song to come to mind when you said that was the chicken dance.

We're really good at this sort of group coordination: -20 karma for sure :)

Have you read http://lesswrong.com/lw/jj/conjunction_controversy_or_how_they_nail_it_down/?

They are rational to the extent they are interested and successful at achieving their goals.

Since so many poker opponents often decide at whim, we need to do more than just strategically analyze their actions relative to what they should be doing. We need to watch and listen and determine what they are doing.

--Mike Caro, Caro's Book of Tells