A bit more on the behavioral psychology definition of extinction:

If a given action is ignored or receives a negative consequence, it will be less likely to be produced next time the same situation arises. This process of decreasing the probability of a behavior occurring is called the extinction of the behavior.

Stan cries when he wants an apple, but instead of getting the apple, we all ignore him. Next time he wants an apple, he will probably try something other than crying.

In this example, the unwanted behavior is crying, the reinforcer for this behavior is the apple (or would be, if we were to give him the apple), and the negative consequence is not getting the apple. Of course, it gets a lot more complicated than that in practice. Stan is probably crying because he has cried before, and it worked. He'll probably try it at least a couple more times before he gives it up, and he'll probably be louder next time. And ignoring people isn't always the best way to get them to do what you want.

For example, let's say that I want to extinguish my daughter's obsessive playing of computer games. If I ignore her while she's playing, there will be no change in her behavior. This is because the reinforcer of her behavior does not come from me, but directly from the computer. I need to pair the playing of computer games with a negative consequence (or, more realistically in this example, take control of the reinforcer, i.e., get control over the computer).

On the other hand, if one of my students likes to swear in order to piss me off and get attention, I may not get far if I punish him for swearing. That only lets him know that his pissing-off-teacher program is right on track, and rewards him with the attention he desires. The stronger I make the punishment, the better he thinks he's doing! I'm better off ignoring his behavior.

Here's some factors that influence the effectiveness of extinction:

  • The control of reinforcers: Make sure you know what the reinforcers are, and that they can be controlled. If you want to stop Stan from crying when he wants apples, you need to make sure that no one gives him apples when he cries. Of course, you may be able to extinguish his crying behavior when it comes to dealing with you, but he'll still cry for everyone else.
  • Control the setting: Ignoring behavior can be very difficult in public places (restaurants, stores, movie theaters), especially when the behavior involves crying and screaming. Be prepared! Be ready to leave or wait it out, but don't give in. If Stan gets an apple only when he cries in public, then he's 1. more likely to try crying again, and 2. especially likely to try when he's in a public place. Also keep in mind that he might not want to go to the grocery store (for example), and if you decide to leave rather than make a scene, you've just taught him that, while he may not get an apple when he cries, he does get to leave the store. Now he has a new reason to cry!
  • Reward appropriate behavior: Extinction will work much better if it is paired with reinforcement for a positive behavior that meets the subject's needs -- that is, if Stan can get what he wants by asking politely, it will be much easier for him to give up crying. Extinction of bad behaviors will work much faster if good behavior is consistently and quickly rewarded (and praised). Don't make the extinction a battle with a winner and a loser -- there should be two winners, you and the subject. Make sure Stan can get his apple, and feel good about doing so.
  • Full disclosure: Things will probably move along a lot faster if the subject of extinction knows exactly what the rules are. "If you cry, you don't get an apple. To get an apple, you should ask 'can I please have an apple?'" If it looks like the behavior is about to start, feel free to remind the subject of the rules. ("You look hungry. Do you remember how to ask for an apple?")
  • Consistency!: Extinction will go faster for a behavior that has been continuously reinforced than for one that has been only intermediate reinforced. If you have intermediately reinforced a behavior, the subject has become more used to persisting, and will have learned that failure this time does not indicate that the behavior wont get him what he wants next time... or the time after that... or the time after that... This is another reason to Control the Reinforcers! Sometimes we accidentally move from continuous reinforcement (get an apple every time you cry) to intermediate reinforcement (get an apple occasionally when you cry) when trying to extinguish a behavior. This is bad, as it will make it harder to get rid of the behavior in the long run.

    Confused by intermediate reinforcement? A common example is a slot machine. You may lose $20 in an afternoon, slowly feeding it quarters. No one would walk up to a row of payphones and start popping quarters randomly into them, even though the end effect will likely be the same, and much faster. The difference is that the slot machines are intermediately reinforced. You don't really expect to get rich, but you do want to try just one more pull... because sometimes it pays off! Now compare the slot machine (intermediately reinforced) to an ATM (continuously reinforced). When the slot machine stops paying off, it could be quite a while before you notice -- and even when you notice, you may think that it only means that the big payoff is coming up any second now. But if an ATM doesn't give you cash, you get worried really quickly. If it happens even twice, you will likely start avoiding that machine. The intermediately reinforced slot machine will be given more chances than the (formally) continuously reinforced ATM. Likewise, intermediately reinforced bad behavior will reoccur more often than continuously reinforced behaviors once the reinforcers have been removed.

  • Extinction burst: a behavior will often become more common for a while before it starts to decrease (and hopefully disappear). When something stops working, people tend to try extra hard for a little bit, then give up. This may mean an increase of crying over days or weeks as Stan tries to get an apple, or a big 30 second flurry of scribbling as I try to get one more burst of ink out of my ball point pen. It would be a big mistake to give up on extinguishing a behavior in the middle of an extinction burst. That would mean that you have reinforced the more extreme level of behavior (it didn't work when Stan was whimpering pitifully for 2 minutes, but crying loudly for 10 minutes worked! Stan ain't no fool, and he now knows to go strait to the screaming, and stick with it!).

So, what with continuous vs. intermediate reinforcement and extinction bursts, there is one big rule to follow when you're trying to extinguish a behavior. Don't Give Up. If you start to withhold the reinforcer (i.e. the apple), but then relent and provided it after a later incidence of the behavior, you will have both taught the subject that if they try long enough they can break you down, and since the behavior was probably more intense and/or more frequent than usual during the extinction burst, you will have reinforced a worse, more obnoxious level of behavior than you originally had been dealing with.

Extinction of behaviors often produces frustration and anger, which produces aggression. Be ready for this, and be ready to wait it out. Other behaviors may increase along with the behaviors targeted for extinction (i.e. fits, crying, hitting, non-compliance, etc., etc.)

Behavior that seems to have been completely extinguished may reappear at a latter date. (tech speak: spontaneous recovery). Usually this spontaneously recovered behavior is more mild than the original behavior. Extinguish it again! It'll be easier this time.

We tend to unwittingly extinguish good behaviors all the time. A child tries to ask for something from his mother; she ignores him and keeps talking to her friend. He keeps saying Mom! Mom! Mom!. No response. Grabs hands. Starts crying. Gets attention! Talking in a normal voice and waiting patiently are both extinguished. Crying is reinforced, so crying will happen all the sooner next time. Eventually, it may be the first, and only, thing the child bothers to try. (I've seen this a hundred times. It's amazing that some children bother to speak at all).

I've talked about extinction as applied to kids, but it also applies to adults and animals. I've also focused more on ignoring behavior rather than punishing it, but punishment is also a fine path to the extinction of behaviors. My cat stopped eating the houseplants because every time he tried it, I squirted him. Ignoring him would not have been at all productive.