"...situational influences often appear to do their work with little regard to the character or personality of the person in the situation... social psychologists have repeatedly found that both disappointing omissions and appalling actions are readily induced through seemingly minor situational manipulations."
This strikes me as relevant to the inevitable discussions about interview dress codes that pop up here during the job season. (For the record, I really enjoy those discussions, and how het up some Smokers get about it.) I think it's interesting how often it is stated (or implied) that there must be a character flaw (lack of virtue?) in interviewers who could be negatively influenced by the clothing (or makeup, or lack thereof) worn by the job candidate. This often appears in something resembling a defense of individual liberty in dress, with the implication being that anyone who is influenced by clothing must be petty, stupid, superficial, sexist, classist (choose your pejorative) if they let something like your suit (or lack thereof) influence their opinion of you as a job candidate.
It strikes me, though, that societal dress codes do their work in the background, like situational influences. The fact that I'm a feminist doesn't stop me from seeing some women's clothing as kinda trashy, for instance, even if the wearer is not, in fact, trashy. I can acknowledge your right to express yourself through your clothing without having to concede that, by the fashion norms of the moment, your clothing is kinda trashy. (And if I can see butt crack, I'm offended -- that goes for guys and gals.) There's a female scientist at the university where I teach. She has made some significant research contributions to her field. But before I knew that about her, I only knew what she looked like, and what she looked like to me is someone who, although young, has had a significant amount of plastic surgery, wears a huge amount of makeup, and wears hooker boots, all of which made it hard for me to take her seriously. I'm pretty liberal about clothing (except the aforementioned coin slots, as well as camel toes, and toe cleavage, which, I'll admit, is my personal bugaboo). I really, really like the fact that, as academics, we typically have more sartorial freedom than people in many other professions have, but were I on an SC interviewing such a candidate, I would probably have the same first impression, based only on her appearance. Her CV, of course, might tell a very different story, but given ten job candidates, all well-qualified (which is to say, all else being equal), her appearance might be a liability for me. And given that she's going to get half an hour of my time, there's a relatively small window of opportunity there to alter my impression.
The point is, when you show up for an interview, your appearance will make an impression (conscious or subconscious, good or bad) on the interviewers, and this impression may have nothing to do with their own character flaws, and everything to do with social norms and situational influences. One way to neutralize factors that are beyond your control, at least as far as clothing is concerned, is to (at least minimally) meet the expectations. This doesn't strike me as evil or onerous, nor as a violation of the individual liberty of someone who is on the job market, any more than expecting you not to behave like a complete asshat (even if you are a complete asshat) is too much to ask. By not drawing attention to your appearance (or asshattedness), you leave more attention for you and your work, no? (Actors -- male and female -- who have had too much plastic surgery distract me no end. I can't watch the performance when I'm continually distracted by the weird topography of their faces.)
There are cases, I would argue, where appearance-based biases would be far more troubling and pernicious: assumptions about skin color, sex, nationality, or disability, for example. But clothing is voluntary, and you have choices. My assumptions about your clothing may be wrong, but it is not unreasonable for me to make some assumptions. Is it?
This is, it's worth noting, a discussion other professions have too.