What Are the Most Common Cognitive Biases?


I was interested to know if there is some consensus on which are the MOST COMMON cognitive biases.

After doing some online searching, which even included a couple of academic papers, there seems to be no consensus on this (admittedly though, confirmation bias was often quoted as one the most common). Different sources tended to list different biases as being "common". In some sources, "common" cognitive biases were simply listed according to alphabetical order.

My guess is that there is probably no consensus on any kind of order of commonality, because the cognitive biases that will come into play really depend upon what kind of tasks / processing one is engaged in on any given day / time period.

Also, I do get the feeling that this is still an emerging field.

Any thoughts on this?

- Rick


Hey Rick,

It's a good question, but a hard one to address head-on because "common" may be too ambiguous or vague to be useful here. The discussions in the popular literature do tend to focus on a "top ten" list, but there are reasons why these show up over and over that may not have much to do with them being "more common" than other biases.

One reason is the way the literature has developed since Kahneman and Tversky's work in the early 1970s. They helped to define a research program and popularized some of the key heuristics ("availability", "representativeness", "anchor and adjust", "affect bias", ''framing", "overconfidence", etc.) and some classic applications in experiments that focused on biases in probabilistic reasoning and biases in decision-making, which was framed as a challenge to standard assumptions of rational choice theories commonly used in economics.

As the "biases and heuristics" research program was extended by other researchers, the pattern of growth looks something like a branching evolutionary tree, with later discussions referring back to the earlier work, and making new distinctions and introducing new biases.

So, just from a sociology of science perspective, those early biases are going to be disproportionately represented in the literature. They have a larger experimental base behind them, more commentary written about them, more examples to illustrate them ... so when the science finally makes it to the public in books and articles, those will be among the "most common" biases that people read about and talk about.

But the popularity of these biases may have little to do with how commonly they make a difference to our behaviour, or how important or consequential they are. That's a very different set of questions.

On these latter questions, there are two things to keep in mind. One is that most of the hundreds of cognitive biases that have been documented are connected to basic cognitive functions that are always operating, like software applications running in the background all the time. So in that sense, they're all "common".

The second thing to keep in mind is that some biases are linked hierarchically to others, and the ones deeper in the hierarchy really are in one sense more common, or more fundamental, than the ones higher up the hierarchy. The Gambler's Fallacy, for example, is a particular bias associated with probability judgments. But it's connected to the "availability heuristic", which is a much more basic and foundational cognitive shortcut. There are many distinct cognitive biases that have roots in the availability heuristic.

This fact, that some cognitive biases are more generic and foundational than others, is another way to talk about some biases being "more common" than others.

Your last comment is right on the mark. "The cognitive biases that will come into play really depend upon what kind of tasks / processing one is engaged in on any given day / time period". That's exactly right. Social biases are going to show up in social contexts, memory biases will show up in memory retrieval contexts, decision biases will show up in decision-making contexts, etc.

Thanks for the question, I hope this is helpful!