Most computer scientists won't notice and will completely
forget what you wore when it comes to decision making time. But the
wrong clothes might make a bad impression on some of them and you
might meet administrators or faculty from other department with
different standards of attire. You never want to give the appearance
that you are not taking the interview seriously.
On the other extreme I have seen candidates looking uncomfortable in
suits they clearly borrowed or bought off the rack. My suggestion,
dress as nicely as you feel comfortable. To be specific, I'd suggest
nice pants and a jacket with or without a tie for men. For women the
best I can say is dress professionally.
Don't feel afraid to ask the person hosting your visit about these
kinds of questions. The host generally wants you to succeed and can
tell you about who you will meet and any expectations they may have.
There is also a East Coast/West Coast difference here. If you wear a suit to an interview at Berkeley, you'll draw attention to your clothes. (This is not a desirable property!)
If you do choose to wear a suit, make sure it is freshly tailored. A misfitting suit makes quite a statement!
In my career, I have seen faculty candidates succeed who only wore tee-shirts and jeans. (In fact, on a percentage basis, those who wear tee shirts are more successful than those wearing suits -- although the sample size is too small to make any statistically significant statement.)
If you wear a suit to an interview at Berkeley, you'll draw attention to your clothes.
Interesting to hear that about Berkeley. I hope candidates (as well as invited speakers?) are told this in advance.
As for me, if I ever get an interview for a job I really care about, I'm going to spend the money on a great outfit that I would never waste money on otherwise. If it helps me in any way to get the job, the investment will have been well worth it.
Interviews are usually two days long with a talk on the first day. Since the interview talk is on the first day, a good plan is to dress up that day and then dress (neatly) on the second day in a way that is compatible with the way the faculty you meet on the first day are dressed. That way, you will implicitly be saying 'I am also one of you' and will likely feel more relaxed. For dressing up, I second Lance's suggestions, particularly that being comfortable in what you wear is important.
The last anonymous did not give good advice since what are you supposed to do, bring many different outfits, so that hopefully one matches what the faculty wears? Obviously, you have to plan all of your outfits in advance.
I used the word 'compatible'. That simply meant that if the faculty tend to be dressed up then you stick with your first day attire on day two and if they aren't then you dress more casually.
A few clarifications. First, there is no rule -- at Berkeley or any major research US university I know of. But wearing a suit in a place where faculty rarely wear suits makes you stand out.
I do not recall seeing women candidates wearing jeans. That question touches on a very important issue: the degree of latent sexism in the "computer science establishment." This is an important topic, and one which should be discussed.
Look at faculty web pages for that department. They (likely) have one of their favorite photos up though there is always the possibility they may have been caught on a bad hair day by an eager dept. web master's digital camera.
For photos that are OBVIOUSLY outdated extrapolate a likely contemporary fashion (assuming good living practices).
grade clothing by level of formality and fabric content. Compute a mean for each to obtain appropriate style and quality and finally choose color based on the current season.
While being a graduate student who is yet to live through this experience to tell the tale, I don't think you can ever go wrong with a really decent formal shirt and trousers with dress shoes. (E.g., light blue or white shirt with full sleeves, black or navy trousers, laced black shoes.) You will not look like somebody who does not take the interview seriously in such an outfit even if your interviewers are all dressed to their tees. More importantly, it is not just the dress but also your "manners" which can make or break how you come across at the interview. I.e., somebody in a great suit can come across as impolite or snobbish or even unconfident while somebody in a "milder" outfit can still connect with the interviewers. So the bottomline IMO is to stay in the middle on the dress side but focus on how you carry yourself. In the end, confidence and comfort will benefit you the most.
I'm a grad student in CS at the University of Minnesota, and here, faculty wear suits about 1% of the time. However, faculty candidates I've seen *always* wear suits.
To me, if a faculty candidate did not wear a suit, he/she unknowingly may put him/herself at a disadvantage. It may appear that the candidate does not take the job seriously or is somehow disrespectful to the school, as compared with the other candidates.
I formerly worked in a casual dress environment in IT at a corporation, and there job candidates typically wore suits, too. Even though they were more dressed up than those of us interviewing them, I didn't feel they were overdressed. Instead, their dress indicated they took the job seriously.
In my experience the academic garb always seems to consist more of sport coats that suits. I don't think that an interviewee would go wrong wearing a classic Navy blue blazer or sport coat, a nice tie and lighter colored trousers. I've worn this combo to what academics would consider pretty formal dinners and not felt out of place. If the VP of Academic affairs can wear it, why not?