Cash or credit: Exploring the pain of paying
Studies suggest the farther you are away from "real" money, the easier it is to spend it.
When you pay cash, you can "feel" the money leaving your control. This isn’t true with credit cards. Flipping a credit card up on a counter registers nothing emotionally.
Chalk it up to a concept called the pain of paying, says Dan Ariely, the author of Predictably Irrational: Imagine that a restaurant, rather than charge $30 per meal, charges by the bite, with a waiter standing tableside ringing up each morsel. That reminder would make for an extremely unpleasant meal.