One of the big difficulties that people face in problem solving is called functional fixedness. Certain types of problems require that we think of a novel use for an object in order to obtain the solution. Functional fixedness gets in the way by latching on to what we know about an object's normal use and refusing to let us think of anything else. For the ultimate success story in overcoming functional fixedness, think of MacGyver. For him, practically nothing has a fixed mundane use; paper clips become lock picks or radio antennae, and chewing gum can defuse a bomb.
Let's take a look at a few examples of functional fixedness-related problems:
Q: You are in a bare room. Two ropes hang from the ceiling; your job is to tie their ends together. Unfortunately, when you're holding the end of one rope, you can't reach the other one. A box of tools sits in one corner of the room, including a hammer, a saw, and a screwdriver. How do you tie the ropes together?
Once you've given that riddle plenty of thought, read the answer below:
A: If you had a counterweight, you could tie it to one of the ropes and start it swinging like a pendulum. Then you could grab the other rope, pull it towards the center, and catch the other rope as it swung toward you. In this case, you have to use one of the tools as the counterweight! (I'd advise against using the saw, though, unless you're a big fan of "The Pit and the Pendulum.")
How'd you do? People who have problems with that riddle tend to do so because of functional fixedness; hammers are usually for pounding nails, not swinging around on ropes. To solve the problem, you have to overcome your preconceived notions of what the tools are for.
Here's another riddle, to demonstrate how even a slight change in phrasing can contribute to a functional fixedness problem:
Q: You've arranged a romantic evening for you and your sweetheart. You told your darling to meet you at a local motel, and that your door will be the one with three candles standing on it at eye level. Okay, you great romancer, now how are you going to get the candles to stand on the door? All you brought to work with is a cardboard box containing three small candles, a book of matches, and a handful of tacks.
Once you've given that a good think, here's the same riddle, with one slight change:
Q: You've arranged a romantic evening for you and your sweetheart. You told your darling to meet you at a local motel, and that your door will be the one with three candles standing on it at eye level. Okay, you great romancer, now how are you going to get the candles to stand on the door? All you brought to work with are three small candles, a book of matches, a handful of tacks, and an empty cardboard box.
Now here's the answer (don't read until you're read for it):
A: Empty the box, if necessary. Use the tacks to pin the cardboard box to the door at eye level. Set the candles on top of the box, and light them with the matches.
Most people find the second phrasing of the problem easier to solve than the first; that's because of functional fixedness. In the first problem, you get hooked on the idea that the box is only there to hold the other stuff. In the second problem, since the box is already empty and not assigned a function, it's easier to think of it as a potential tool in solving the problem.
This is fascinating stuff on its own, but I wouldn't be bringing it up unless I could tie it in to something quirky, like a Japanese game show. This whole clip is entertaining, but in particular we get a functional fixedness problem right off the bat with the first contestant:
All the contestant has to do is pass through the hole. In this case, the first hole is shaped like a human caricature with a tiny body and giant head. It's obvious that the arms and legs of the person-hole are too small for anyone to fit through, but the contestant gets caught in the trap of functional fixedness. He tries to put his head through the head-hole, arms through the arm-holes, and legs through the leg-holes. It doesn't seem to occur to him to try to fit his whole body through the over-sized head-hole.
Unfortunately, though psychologists have come a long way in classifying different kinds of problem solving behavior (like functional fixedness), we've still got a ways to go before we understand the brain mechanisms behind such behaviors. But identifying a phenomenon is the first step to understanding it.
Can you think of any other examples of functional fixedness problems?