Imagine that you need to drive a nail into a wall so you can hang a framed photo. Unable to find a hammer, you spend a significant amount of time searching your house to find the missing tool. A friend comes over and suggests using a metal wrench instead to pound the nail into the wall. Why didn't you think of using the metal wrench? Psychologists suggest that something known as functional fixedness often prevents us from thinking of alternative solutions to problems and different uses for objects.