There is a whole chapter on this in Simon Webb's book "Chess for Tigers". If you haven't read it, I recommend it. It's unlike any other chess book I've ever seen, and it's a very entertaining read.
Advice for rating anxiety/overconfidence when player matching.
Sort:
When you get paired against someone whose Elo is a fair bit higher than yours, remember that they have a lot more to prove (and lose) than you do. It's perfectly reasonable to expect that you'll lose, but that should motivate you to try extra hard to get an upset victory.
On the other hand, if you are the person with a higher Elo, don't get comfortable. You never know if a user who's lower than you is actually a person that's having a really bad day and doesn't know when to quit. Chances are you could be up against someone whose rating is way lower than it should be.
If this is hard for you to do, there is an option to hide your opponent's rating/username. This is actually much more useful when you reach the "titled player" stage, since that's where you're going to potentially encounter some very famous players, but maybe it'll help you as well.