I'm not sure what you mean by praise-free zone, so I'm not sure if I'm answering the right question here. When I made top 12 on the Putnam, the professors who were aware of it congratulated me; I don't think they congratulated people in general who made honorable mention, although possibly because that consisted of several people. In my lab, if someone wins an award we generally send out an e-mail to the lab mailing list congratulating them. A particularly clever insight will elicit someone saying "that's a nice way of thinking about the problem". (I should also note that I'm probably one of the more capable undergrads so I might receive more positive feedback than the average person.) Of course these sorts of things are difficult and probably only happen a few times a week (on the level of insights) and much rarer on the level of meaningful awards, so if you want someone to be praising you every time you do well on a problem set then MIT is probably not the place for you.

Re: MIT... well, I went there, but it was >20 years ago, so I can't speak to what it's like now with any significant credibility. That said, I am at least peripherally involved in its social milieu... in fact, I'm having my wedding reception there later this year... so I guess I'm not completely disconnected. The impression I get is that the "praise-free zone" nature of the place hasn't changed and isn't likely to. There's a strong cultural bias towards what I think of as the UNIX attitude towards feedback -- "there's no reason to provide any return values on success; if something had gone wrong we would have told you" -- which means that creating your own reward structure is an important skill.