layout: post
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title: "The Availability Heuristic "
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imagefeature: "kahneman-HI.jpg"
imagecredit: Princeton University
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Imagine you've just opened a hypothetical 2,000-word blog post (or essay). I'd like to ask you two questions about your expectations for this piece of writing. Don't spend too much time deliberating about these; trust your instincts.

First, how many words do you expect to see that follow the form -----n- (seven letters with an "n" in the 6th spot, which we will call Group 1)?

1.	0
2.	1-2
3.	3-4
4.	5-7
5.	8-10
6.	11-15
7.	16 or more

Second, how many words do you expect to see that follow the form ----ing (seven letters ending in "ing", which we will call Group 2)

1.	0
2.	1-2
3.	3-4
4.	5-7
5.	8-10
6.	11-15
7.	16 or more

Here's a picture of Nobel Laureate Daniel Kahneman so you can come up with your answers before reading ahead.

![kahneman-HI.jpg](/images/kahneman-HI.jpg)

As some of you will have noticed, every word that fits into the Group 2 must also be in Group 1 (in other words, every "----ing" word is also a "-----n-" word). It is also likely that the passage contains a few Group 1 words that don't follow the Group 2 pattern. So logically, the passage must contain as many Group 1 words as Group 2 words, and probably more Group 1 words.

Feel like you might need to rethink your guesses? You're not alone. If you predicted there would be more Group 2 words than Group 1 words, you probably fell victim to the availability heuristic. 

The availability heuristic is a mental shortcut where people estimate the frequency of an event according to how easy it is to think of supporting examples. In this case, it's easy to think of examples of Group 2 words. Simply come up with an appropriate verb and add the "-ing" as in running, jumping, or dancing. The form of Group 1 isn't as obviously associated with a certain segment of words as Group 2. Focusing on just the "n" might lead you to come up with words like someone, actions, or husband. However, these take more work to think of than the Group 2 words (unless, of course, you notice that you can use Group 2 words for Group 1).

Because it's so much easier to think of examples of Group 2 words, most people estimate that they will occur much more frequently in a text. When the aforementioned Kahneman and collaborator Amos Tversky conducted this experiment, the median estimate for Group 1 was 4.4 words while the median estimate for Group 2 was 13.4 words. 

As the above example shows, the availability heuristic has some powerful effects on our ability to think rationally. Here are some other places where it makes an impact.

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## **When facts aren't facts: Who cleans more?**

If you've ever had a roommate, you've probably experienced the feeling that you're doing more than your share of some tasks (or maybe every task). You might be surprised to learn that your evaluation of this may be influenced by the availability heuristic. 

In one study, researchers asked married couples to estimate how responsible they were for 20 relevant activities like making breakfast, caring for children, and cleaning the house. They also included negative activities such as causing arguments.

In 16 of 20 activities, the combined responsibility that couples attributed to themselves showed statistically significant overestimation (the other four had nonsignificant differences--none showed underestimation). In other words, when you add up the credit the husband takes and the credit the wife takes, you get a number greater than 100% of the responsibility for the activity. Noteworthy is that this trend held true for both positive and negative activities, showing it's not simply a matter of narcissism.

When considering what portion of a shared task we're responsible for, it's easier to think of examples where we performed the task rather than someone else. As a result, we tend to overestimate how much we've really done. 

Keep this in mind next time you feel certain your roommate is freeloading off of your generosity. Then again, maybe (s)he really is a useless bum.

---


## **When opinions aren't opinions: What do you think of BMWs?**

Not only does the availability heuristic affect our memories, it can also influence our opinions. 

In another study, researchers asked participants to perform one of four tasks: 

1.	List one reason to buy a BMW (One-For)
2.	List one reason not to buy a BMW (One-Against)
3.	List ten reasons to buy a BMW (Ten-For)
4.	List ten reasons not to buy a BMW (Ten-Against)

Following this, participants were asked questions about their evaluation of BMWs.

Perhaps unsurprisingly, the results showed that those in the One-For group gave BMWs higher ratings (5.6 out of 7) than those in the One-Against group (4.7). Asking participants to give a reason in favor reminded them of what they like about the cars while asking them to give a reason against reminded them of what the negatives. However, the surprise came when participants in the Ten-For group reported lower opinions (4.4) of BMWs than those in the Ten-Against group (5.9). In other words, asking them to list ten reasons caused a reversal of what was observed when asking them to list only one. 

Why did this happen? Remember that the availability heuristic causes us to feel that things that are easier to think of support for are more true. Generating one reason to like or dislike a BMW is a breeze; coming up with ten takes a lot of work. Our brain says _"Thinking up that list was [easy/hard], so that must be a [correct/incorrect] position."_

The key idea here is that our opinions can be influenced and manipulated by the cognitive ease of supporting or refuting them. In fact, they're pliable enough that the ease of a related task can be enough to affect them. The idea that humans can be systematically irrational has grown in popularity over the last several years. Studies like this one reveal that we don't even know our own preferences. 

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To conclude, I'd like to say that most of the time, the availability heuristic works in our favor. Without it, we'd have to conduct a mini-survey every time we wanted to estimate something, so it saves a ton of cognitive resources and time. Let's say I'm driving and when my light turns green, I catch a glance of another car going a little too fast towards his red light. My memory quickly references the (easily available) time I almost got hit by a car running a red, and tells me this driver is liable to do the same. I elect to wait until he either passes the intersection or slows down enough to where I know he will stop. In this scenario, I'm thankful for the extra second I get from using this heuristic and I don't care about the difference between a 25% and 75% chance the car runs the light. Speed, not precision, is what matters here. That said, we should be mindful of how availability can affect our perceptions and behaviors.

One final note, in case you were curious: _Of the 1,219 words in this post, 20 (1.6%) are in Group 1 (including the first) and 10 (0.8%) are in Group 2._