Representativeness
One of the most important tasks our minds perform is categorizing things. We need to know the difference between “food” and “not food”, for example, and to eat one and not the other. We also use categories to make predictions: “I don’t recognize that animal, but it’s big and has long canines, so it might be the kind that eats people”. One way we make these categorizations is by using the representative heuristic. We decide how to classify things based on how well they match our mental representation of other things in that category. That’s awfully abstract, so here’s an example: if I see a large, muscle-bound man in athletic gear walking down the street while vigorously chewing gum, I figure he’s more likely to be a football coach than an accountant, because he matches my mental representation of a coach much better.
The problem is, he might be an accountant. Making judgments based on representativeness is useful, but it can lead us astray. Imagine that you see a small, neatly dressed man in glasses, reading a book. Take a second to think: is that guy more likely to be a librarian or an electrician? Librarian, right? Not so fast. There are actually 16 times as many male electricians as male librarians in the United States. So he’s probably more likely to be an electrician, even if he doesn’t fit the stereotype. This kind of error is called the base rate fallacy, and the representative heuristic is usually to blame for it. We ignore the base rate--the frequency of occurrence--of things (librarians and electricians, in this case) and make judgements based on representativeness.
The word “bias” usually means something different when we’re talking about cognitive biases than when we’re talking about biased perceptions of groups of people. But in this case, the two kinds of biases are linked. After all, representativeness is really just another word for “stereotype”. We probably can’t avoid stereotypes altogether, but we can let our System 2 minds step in and say, “Wait a minute, let’s not jump to conclusions about people.” Not everybody matches a stereotype and not all stereotypes are accurate.
Availability
Let’s look at another common heuristic. Consider this question: are there more words in English with the letter “k” as the first letter, or the third letter? Most people guess that more words start with a “k”, but in fact words with “k” as the third letter are three times as common. People get it wrong because words that start with “k” are easier to call to mind. This is called the availability heuristic. We estimate how common things and events are by how easily they come to mind--by how available they are to consciousness.
But this can be a pretty unreliable method, especially in the days of mass media. For example, if you live in the United States, take a couple of seconds to answer this question: Which worries you more, that you or a family member could be a victim of:
1. A mass shooting
2. A fatal accident
It’s no secret that the United States has a problem with mass shootings. Every few weeks some deranged person kills multiple people, and the tragedy dominates the national news for a few days. Not surprisingly, many people are far more worried about mass shootings than fatal accidents. But consider this: according to the Congressional Research Service*, between 1999 (the year of the Columbine shooting) and 2013, 1,554 people were killed in mass shootings. In the same time period, 1.73 million people were killed in accidents. That means the average American was over a thousand times as likely to die in an accident as in a mass shooting. The top accidental causes of death were car crashes, accidental poisonings (including overdoses--these have risen in recent years), and falls. All three are hundreds of times as likely to kill the average American as mass shootings. Indeed, twice as many people are killed in bicycle crashes as in mass shootings. Yet people worry far more about mass shootings than these other causes, because mass shootings are more memorable. The more common causes of death don’t make the news as much, precisely because they’re so common.
To be clear, I’m not saying that mass shootings aren’t a terrible problem, and I’m not making any argument about gun policy in the US. I’m just saying we shouldn’t let the availability heuristic distort our thinking about what’s most dangerous. Why? Because misunderstanding what’s dangerous is itself dangerous. For example, after the 9/11 terrorist attacks, many Americans were afraid to fly, so they drove instead, even though driving is much more dangerous than flying. It’s been estimated that this caused about 1600 extra traffic fatalities in the year after 9-11. This is another case where a lack of critical thinking actually killed people.
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* The CRS report defines a “public mass shooting” as an incident where 4 or more people are killed. This may be a little too restrictive. If you use the definition of a mass shooting by the Gun Violence Archive, which defines a mass shooting as “four or more people shot/killed” and add up deaths for 2014-2016 (the only years that overlap between the Gun Violence Archive and Centers for Disease Control data) there were 1084 deaths in those shootings. Even with this much more expansive definition, the average American in these years was over 100 times as likely to die of poisoning or in a car crash as in a mass shooting. Slightly more people were killed in mass shootings in these three years than bicycle accidents (928 people). None of this is to say that gun homicide in general isn’t a big problem. In 2014-2016, there were 38,402 gun homicides--the fifth-highest cause of death by injury. https://fas.org/sgp/crs/misc/R44126.pdf
** https://www.cdc.gov/injury/wisqars/index.html
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