thinkingispower.com
Guide to the Most Common Cognitive
Biases and Heuristics
Melanie
27–35 minuter
Our brains have to process an infinite amount of stimuli and make
an endless number of decisions. So to save time and mental
energy, our brains rely on heuristics, or short-cuts. Think of
heuristics like guidelines, or rules of thumb: they’re usually good
enough most of the time, but they can result in errors.
Cognitive biases are systematic errors in thinking that interfere
with how we reason, process information, and perceive reality.
Basically, biases deviate our thinking away from objective reality
and cause us to draw incorrect conclusions.
Biases and heuristics are part of our automatic or intuitive system
of thinking, so they occur without our awareness. But because they
impact nearly all of our thinking and decision making, familiarity
with the most common errors is a great way to become a better
critical thinker.
[Before reading about individual biases and heuristics, the following
post is strongly recommended: Should you trust your intuition? The
elephant and rider inside your mind]
A note on how to use this post: This page is a resource of the most
common cognitive biases and heuristics, and is not intended to be
read from top to bottom. Feel free to share the graphics to help
others learn more about how to be better thinkers.
A very brief background
Cognitive biases and heuristics were first described by Amos
Tversky and Daniel Kahneman in the 1970s. While Tversky died in
1996, Kahneman won the 2002 Nobel Prize in Economics for their
work, which he later summarized in his best-selling (and must-read)
book, Thinking, Fast and Slow.
Resources
Positive Psychology: Cognitive biases defined: 7 examples and
resources
The Decision Lab: Cognitive biases
Effectivology: Cognitive biases: What they are and how the affect
people
Big Think: 200 cognitive biases rule our everyday thinking. A new
codex boils them down to 4. (Updated Codex)
Confirmation Bias
Definition and explanation: Confirmation bias refers to the
tendency to search for, interpret, and remember information that
confirms our beliefs. In short, we prefer information that tells us
we’re right…and we’re more likely to remember the hits and forget
the misses.
In a world full of too much information, our brains need to take
short-cuts. Unfortunately, some of these short-cuts can lead us
astray. In the case of confirmation bias, the short-cut is: Does this
piece of information support what I already think is true? If so, we
assume there’s no need to question it.
Of all the biases, confirmation bias is the most powerful and
pervasive, constantly filtering reality without our awareness to
support our existing beliefs. It’s also self-reinforcing: because
confirmation bias makes it seem like our beliefs are supported by
evidence, we grow even more confident we’re right, and thus the
more we filter and ignore information that would change our mind.
[Learn more: The person who lies to you the most…is you]
A prime example of confirmation bias plays out in our modern
media environment, where we’re able to select news organizations
and even the types of stories that validate our worldview. With the
help of algorithms that learn our preferences, we can get trapped in
filter bubbles, or personal information ecosystems, where we’re
served more and more content that reaffirms our existing beliefs
and protected from evidence that we’re wrong. (We really don’t like
being wrong.) In essence, we assume our news feed is telling us
about reality, when the reality is it’s telling us about us.
Confirmation bias is also one of the biggest reasons we fall for
“fake news.” Why bother spending time and energy fact checking
that viral video or news story or meme when it already fits with what
you believe? It feels true, so it must be!
Another example of confirmation bias is the common (but mistaken)
belief that the full moon impacts behavior. Indeed, the full moon is
often blamed by nurses and doctors for an increase in hospital
admissions and the police for an increase in crime. (It’s fun to note
that the root of the words lunacy and lunatic come from the Latin
luna for moon.) To be clear, there is no good evidence that the
moon has any of these impacts.
So why then does this belief persist? Imagine a teacher who
believes in the full moon effect. He notices his students seem to be
a little rambunctious and thinks, “It must be a full moon.” If it is a full
moon, he confirms – and probably becomes even more confident in
– his belief. If it’s not a full moon, he quickly interprets their behavior
differently or blames it on something else. And in the future, he’s
much more likely to remember the examples that supported his
belief and forget the others.
[Learn more: “Why do we still believe in ‘lunacy’ during a full
moon?”]
How to overcome confirmation bias: Confirmation bias is
amongst the most prevalent and influential of all the biases, so it’s
important that critical thinkers try their best to reduce its impact.
Here are a few tips:
• Learn to recognize when you’re prone to confirmation bias, such as
when a belief is tied to strong emotions and/or you’re confident
you’re right. So slow down and don’t let your emotions guide your
reasoning. And avoid overconfidence! The more certain you are
that a belief is true, the less likely you are to question it.
• Be open to being wrong! The more tightly we hold our beliefs, the
more contradictory evidence is viewed as a threat. But if you can’t
change your mind with new evidence you’ll never be able to learn.
Instead, separate your beliefs from your identity: You aren’t wrong,
the belief is.
• Go one step further and search for evidence that would prove you
wrong. In today’s information-saturated environment, if you’re
looking for evidence that you’re right, you will find it. So instead,
search for disconfirming evidence! If the belief is true it will
withstand scrutiny.
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Dunning-Kruger Effect
Definition and explanation: Have you ever noticed that those who
know the least are often the most confident? It has a name: the
Dunning-Kruger effect.
The Dunning-Kruger effect is a cognitive bias in which people
overestimate their knowledge or abilities, resulting in undeserved
overconfidence. Essentially, poor performers are unable to
recognize their own mistakes and limits, so they assume they’re
awesome. The reason is that (paradoxically) the skills and
knowledge required to be competent at a task are the same skills
needed to evaluate one’s own competence. Basically, ignorant
people don’t know enough to recognize how ignorant they are.
But why are the incompetent so overconfident? Contrary to what
many people believe, an ignorant mind is not a clean slate. Our
brains are constantly trying to make sense of the world, using prior
knowledge and experiences. Once we form beliefs and narratives,
confirmation bias kicks in, and we unconsciously seek out
information that supports our ideas. The result is a mind cluttered
with misleading experiences, random facts, and intuitions that feels
a lot like knowledge. And this powerful sense of false knowledge is
what leads to overconfidence.
You’ve almost certainly witnessed the Dunning-Kruger effect. From
dreadful American Idol contestants who can’t fathom why the
judges laughed, to ignorant social media commentators LOUDLY
proclaiming their opinions, it can be both hilarious and frustrating.
That said, it’s important to keep in mind that all of us are prone to
this bias. Think for a moment about something you’re really good
at. It might be fixing cars, breeding Basset hounds, baking bread, or
playing Call of Duty…. anything you’re an expert in. Now consider
what the average person knows (or doesn’t). It’s probably not
much, and some of it is probably wrong. They probably don’t even
realize how much there is to know.
Now consider that you’re that ignorant in basically every other area.
I hope you’re humbled by that realization. We are all blind to our
ignorance. We are all overconfident idiots.
There are real consequences to overconfidence. Not only do the
incompetent overestimate their skills, they’re unable to recognize
true expertise. And if you already know everything, why would you
learn? Or change your mind?
[Learn more: Overconfident Idiots: Why Incompetence Breeds
Certainty]
How to overcome the Dunning-Kruger effect: At the root of the
Dunning-Kruger effect is a lack of self-awareness. Essentially, we
are unable to objectively evaluate our own knowledge and
competence. Therefore one key solution is metacognition, or being
aware of our thought processes, with the goal of assessing and
improving our understanding and performance.
Also important is intellectual humility, or the recognition that you
might be wrong. Be curious about what you don’t know. Ask for
feedback from experts, and be open to incorporating their
suggestions. Most issues are more complicated than we think, and
understanding their complexity and nuance requires deep
knowledge and expertise. If the answer seems simple and obvious
to you, and yet somehow experts have “missed” it, consider it might
be you that’s wrong.
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Availability Heuristic
Definition and explanation: The availability heuristic is a mental
short-cut in which we estimate how likely or important something is
based on how easily we can think of examples. However, because
we are more likely to remember events that are recent, vivid, or
emotional, we overestimate the likelihood of certain events and
may make poor decisions.
Consider the following examples:
• You’re at the beach, thinking about going into the water, and
images of shark attacks pop into your head. You sit and read a
book instead.
• You recently saw a plane crash on the news, and you were already
scared of flying, so you decide to drive on your next trip.
• You just watched a documentary about someone who won big on
the slot machines, so you plan a trip to the casino. Someone has to
win…it might as well be you!
• You’re worried about someone kidnapping your child because you
saw news coverage of an attempted abduction. Thankfully, the child
wasn’t harmed, but you don’t want to risk it. Today’s world is so
much more dangerous than it was when you were young.
In all of these cases, you assumed something was likely because
you could easily think of examples. Yet shark attacks are
exceedingly rare, flying is orders of magnitude safer than driving,
the chances of winning at the slots are miniscule, and there’s never
been a safer time to be a kid. By confusing ease of recall with the
truth, your brain misled you. And as a result you make poor
decisions.
One of the biggest influences on our perception of risk is news
coverage. By definition, the news covers events that are new and
noteworthy, and not necessarily things that are common. News
reports of murders and horrible crimes (or shark attacks and plane
crashes) can result in us thinking these events are more common
than they really are.
How to overcome the availability heuristic: The first step in
overcoming any heuristic is awareness. Remember, the goal is to
determine how likely something is in order to make better
decisions. Short-cuts help us think fast, but they aren’t always
reliable.
So slow down your thinking and don’t assume the first thing that
pops into your head is representative of reality. Try to identify the
stories your brain is using as evidence, and notice any emotions
connected to them. Then if possible, use statistics instead!
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anchoring effect
Written by Jon Guy
Other names: Anchoring heuristic
Definition and explanation: The anchoring effect refers to our
tendency to “anchor” to the first piece of information we learn about
something, and form our beliefs about that thing based on the
anchor. Newer information isn’t evaluated objectively, but, rather,
through the lens of the anchor. The anchoring effect is an extremely
common cognitive bias, and one that can interfere with our abilities
to make good decisions and objectively understand reality.
Therefore, understanding the anchoring effect can save us time,
money, and improve the quality of our thinking.
The anchoring effect occurs when we unwittingly cling to the first bit
of information we get about something. However, if we’re not
careful, anchoring can result in poor decisions that we may regret.
For example, you discover that the new car you’d like to purchase
costs an average of $25,500 (the anchor). So you take a trip to a
local dealership, and the salesperson offers to sell you the vehicle
for $24,000. “What an amazing deal,” you think, as you drive off the
lot in your new car. Later you learn that several other dealerships
around town are selling the same vehicle for $23,000! Since you
were anchored to the original $25,500, anything less sounded like a
good deal, and that anchor kept you from pursuing prices at other
local dealerships.
But as I mentioned earlier, anchoring can be tricky. Not only does it
affect many of our decisions, it can even affect decisions that are
made for us. For instance, if your doctor anchors to the first
symptoms you report about an illness, she might misdiagnose you
without pursuing other possible explanations. Or, if you’re waiting
on a decision from a jury on an insurance settlement case, their
decision on how much to award you might be influenced by a
strategically placed anchor.
Most people agree that taking care of our health is one of the more
important goals we pursue throughout our lives. But let’s say your
grandparents and great-grandparents were all very long-lived. You
might anchor to their longevity as an expectation of how long you
will live, without taking into consideration that they might have lived
much more healthy and active lifestyles than you do. Therefore, by
anchoring to one piece of information (how long they lived) and
ignoring other, more important pieces of information (how they took
care of themselves), you could wind up neglecting your own health
by eating poorly or exercising infrequently.
The anchoring effect is so powerful that the anchor doesn’t even
have to be relevant to the thing we’re making a decision about! For
example, researchers have shown that putting an expensive car on
a restaurant menu actually resulted in people spending more
money while dining there. Other researchers have shown that by
simply asking people the last two digits of their social security
number and then showing them a list of products, those whose last
two digits were higher were willing to pay more for the products
than those whose digits were lower.
How to overcome the anchoring effect: The anchoring effect is
an extremely pervasive bias, and even contributes to other biases.
Moreover, since anchoring happens outside of our conscious
awareness, interrupting the process can be rather challenging.
Therefore, it is important to understand the effects of anchoring, so
that we might stand a chance of overcoming them.
For example, thinking long and hard about an important decision
always sounds like a good idea, right? Intuitively, this makes sense.
However, if we’re merely thinking deeply about the anchor, we’re
just amplifying its effects, and probably digging ourselves even
deeper into our biases.
Fortunately, there are some strategies we can use to combat, if not
completely overcome, the anchoring effect, such as by practicing
metacognition. We are cognitive misers, which means overcoming
our biases requires us to maximize metacognition; an awareness
and understanding of our own thought processes. Or as I like to call
it, thinking about thinking.
Another strategy we can employ is to try to consider alternative
options. If you see t-shirts on sale for 3 for $10, consider that you
may only need one, or that you might not need any! Anything you
can do to interrupt the decision-making process can help to slow
down your thinking and give you the time you need to make a
better decision.
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Representativeness heuristic
Written by Jon Guy
Definition and explanation: The representativeness heuristic
doesn’t exactly flow easily off the tongue. Nonetheless, this
heuristic is well worth our attention. Like all heuristics, the
representativeness heuristic is a mental shortcut our brains take to
preserve its limited resources, in this case to make quick judgments
about the likelihood of something based on how similar it is to
existing mental categories.
The representativeness heuristic is an error of reasoning that
occurs when we make generalizations based on our mental models
of reality. To use a classic example, let’s say I told you that Mary is
a quiet, shy introvert who’s not very interested in getting to know
people and is also very detail oriented. Based on this description, is
it more likely that Mary is a librarian or a mechanic? Our gut tells us
that Mary is much more likely to be a librarian because her
characteristics sound more representative of our mental models of
librarians.
But the representativeness heuristic doesn’t just apply to our
perceptions of people. For example, imagine you’re going to your
friend’s house for the first time, and he tells you that he has two
dogs and one of them is occasionally aggressive. When you arrive,
you see that he has one pit bull and one pug, and, like many
people, you assume the aggressive dog is the pit bull. Later, you
learn that the pit bull is mild mannered, while the pug is the one
with the hot temper.
The reason most of us would assume the pit bull is more likely to
be aggressive is because of our mental constructs of both pit bulls
and pugs; that is, pit bulls have a (false) reputation for being
aggressive, while pugs do not. In this situation, we unwittingly
assumed that our mental construct was correct, and, as a result, we
misconstrued reality.
Perhaps the best example of the representativeness heuristic is
stereotyping. Stereotyping occurs when we make judgments about
all people within a group based on our mental construct of that
group. For instance, we might assume that all Indians enjoy spicy
foods, or all Native Americans are highly spiritual, or all rich people
are snobs, or all homeless people are drug addicts and alcoholics.
However, in each of these examples, our mental models will be
wrong much of the time, and so it’s up to us to think critically and
question the assumptions that lead our brains to misinterpret reality.
Heuristics are short-cuts our brains take to save energy.
Importantly, they aren’t necessarily bad and don’t always lead us
astray. Additionally, our brains categorize things (i.e. people,
places, events, objects, etc) based on our previous experiences so
we know what to expect and how to react when we encounter
something new in that category. If we didn’t categorize things, every
new thing we encountered would overwhelm us! So, while the
representativeness heuristic can cause us to misconstrue reality,
it’s also a valuable tool that helps us navigate our daily lives. Rather
than trying to determine if every moving car is potentially
dangerous, we draw on our mental models of moving vehicles, and
treat them all with caution. Likewise, if a grizzly bear was running
our way, we’d know we were in trouble, but if a tumbleweed was
speeding towards us, we’d know we have nothing to fear.
Even though the representativeness heuristic can be a useful tool,
it’s still important for us to maintain our skepticism and practice our
critical thinking skills. While categorizing things assists our brains in
reducing its cognitive load, we need to remember that even our
mental constructs might be wrong, and understand how easily
stereotypes can become prejudices. Moreover, categorizing limits
our ability to see similarities and differences between different
things, and, when we pay too much attention to specific
boundaries, we further limit our ability to see the whole.
As the foregoing examples show, the representativeness heuristic
can affect our judgment in both trivial and nontrivial ways. It’s not
that big of a deal to incorrectly assume that the guy wearing a suit
is a businessman, when he’s actually a plumber headed to a
costume party. However, judging one individual based on a
stereotypical example is a major driver of racism, sexism, classism,
and even speciesism. Therefore, becoming better educated about
our mental shortcomings goes a long way toward making the world
a better place.
How to avoid the representativeness heuristic: Biases are part
of human nature, and oftentimes serve valuable purposes. As such,
completely avoiding the representativeness heuristic is unlikely, and
undesirable. However, there are several things we can do to
minimize the number of times we fall for it, as well as reduce its
effects when we inevitably slip up.
Awareness of our biases is bias kryptonite, so understanding when
we’re vulnerable, sharing what you’ve learned about it with others,
and developing critical thinking skills are excellent ways to avoid
this bias.
Finally, education can help us combat cognitive biases. Learning
formal logic, becoming a better statistical thinker, or studying other
errors of human cognition are all great ways to minimize our biases,
become better thinkers, and perceive reality on reality’s terms.
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Barnum Effect (aka Forer Effect)
Definition and explanation: If you’ve ever read your horoscope,
visited a psychic, or even taken a personality test and thought,
“Wow, that was so accurate! How did they know?!?”, you’ve likely
fallen for the Barnum effect. The Barnum effect describes the
tendency for people to believe that vague personality descriptions
apply uniquely to them, even though they apply to nearly everyone.
The Barnum effect is named after the famous showman P.T.
Barnum, but it was first described by psychologist Bertram Forer in
1948 (hence its other name). In an experiment on psychology’s
favorite “lab rat” (i.e. undergraduates), Forer gave his students
personality tests and told them he would analyze and provide each
with individualized feedback. Overall, the class rated their results as
very accurate (an average of 4.3 out of 5).
The kicker, of course, was that all students received the exact same
results, which included statements such as:
• You have a great need for people to like and admire you.
• You have a tendency to be critical of yourself.
• Disciplined and self-controlled outside, you tend to be worrisome
and insecure inside.
• At times you have serious doubts as to whether you have made the
right decision or done the right thing.
It’s not hard to understand why the students thought these
statements applied to them…they apply to nearly everyone. But the
students interpreted the generic statements as applying specifically
to them. Thus, they fell for the Barnum effect.
To understand why, let’s take a closer at the statements that
produce the Barnum effect. Barnum statements are general and
applicable to nearly everyone. But their vagueness is their
“strength,” as individuals each interpret them with their own
meaning. They’re also mostly positive, as we prefer being flattered
to hearing negative things about ourselves. And they often include
qualifiers, like “at times”, or simultaneously attribute opposing
characteristics, so that they’re almost never wrong.
Forer rightly attributed the results of his experiment to his students’
gullibility. But the truth is, we’re all gullible to some degree, which is
why the Barnum effect is frequently exploited by those seeking to
convince us they have deep insight into our personal psychology.
How to avoid falling for the Barnum effect: Your best line of
defense against the Barnum effect is awareness and skepticism.
• Be on guard for situations where vague information might be giving
the impression that results are specifically tailored to you, such as
fortune tellers, horoscopes, psychics, personality tests (e.g. MBTI),
online quizzes, and even Netflix watchlists.
• Remember to insist on sufficient evidence to accept any claim. Ask
yourself: Could this “personalized” feedback apply to others? Am I
falling for flattery? And importantly, do I want to believe? Skepticism
is the best way to protect yourself against being fooled…but no one
can fool us like we can.
Final note: While many people associate P.T. Barnum with the
saying “there’s a sucker born every minute,” there’s actually no
good evidence he said those words. For a phrase that describes
our tendency to be gullible, isn’t it ironic?
[Learn more: Learn to be a psychic with these 7 tricks]
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Sunk cost fallacy
Written by Jon Guy
Other names: Escalation of commitment heuristic
Definition and explanation: The sunk cost fallacy describes our
tendency to stick with a decision we’ve invested resources into,
regardless of the increasing negative consequences of that
decision. If you’ve ever wondered why you continue watching a
boring movie, or why you proceed through a terribly uninteresting
book, it might be because of the sunk cost fallacy. The better we
understand the sunk cost fallacy, the more likely we are to catch
ourselves committing it and thus the better positioned we are to
prevent ourselves from continuing on with a losing course of action.
For many of us, once we’ve invested into something, it can be
really difficult to cut our losses, and instead, we end up “throwing
good money after bad.” For instance, if you’ve ever tried to bluff
your way through a hand of poker, you know just how hard it can be
to fold once you’re “pot committed.” However, instead of folding,
you up the ante, hoping that an even bigger bluff will prevent an
impending loss. But in life, the stakes are much higher than they
are in poker.
If the consequences of our actions have a negative impact, the
rational thing to do is stop engaging in that action. The problem is,
when we’ve spent time, money, or effort pursuing a decision, rather
than rationally looking at the negative consequences of continuing
to pursue that decision, we tend to look at it from the perspective of
“losing” that time, money, or effort. Of course, that time, money, or
effort is already gone (they are, after all, sunk costs), and
continuing with our commitment is unlikely to bring any of it back.
Typically, we commit the sunk cost fallacy because we don’t want to
“lose” our investment, even if we wind up more damaged than if we
had simply cut our losses. Put another way, it makes no rational
sense to continue losing simply because you’ve already lost,
especially since you can’t protect an investment you can’t get back
anyway.
The sunk cost fallacy can dramatically affect us as individuals, and
can hugely impact the course of our lives. For example, we might
stay in a relationship that isn’t good for us, or one we no longer
want to be in, because of how much we’ve invested into the
relationship. We might remain at a job we can’t stand, simply
because of how much work we’ve done for the company. We might
continue spending money fixing a run-down car, when it would
clearly be cheaper to buy a new one. Or we might remain in the
same social circle because of how much history we have with the
people in it, even though we no longer share the same interests or
values.
Additionally, the sunk cost fallacy has a number of systemic effects.
Oftentimes, government projects that don’t meet expectations
continue receiving funding simply because so much has already
been invested into them. Both Lyndon B. Johnson and George W.
Bush continued sending soldiers into losing wars, and spent billions
of dollars on what they both knew were hopeless causes. Thus,
when it comes to fallacious thinking, sometimes lives are literally at
stake.
Another pressing danger of the sunk cost fallacy is that it leads to
the snowball effect, wherein we try to protect our investments by
investing even more. The more we invest into something, the more
we feel like we need to commit to it, which means we’ll likely
expend more resources pursuing the endeavor.
How to overcome the sunk cost fallacy: Sometimes, when we
find ourselves in a hole, the best thing we can do is stop digging.
However, in order to do so, we must first recognize that we’re in a
hole. Therefore, awareness is our first line of defense against the
sunk cost fallacy. If you find yourself focused on prior losses rather
than current or future costs, you can use this awareness as a signal
to don your skeptical spectacles and think critically about your
situation.
In addition, we should also carefully consider whether the
investment we’re trying to protect is actually recoverable, or if it
truly is just a sunken cost. Therefore, it’s good practice to ask
yourself, “If there’s no way to get back what I’ve already put into
something, am I better off investing further, or is cutting my losses
the better option?”
Lastly, we should try to recognize the difference between making a
decision that’s based on our emotions, and making a decision that’s
based on reason. Emotions are both powerful and important drivers
of our decision-making, and, like it or not, we are emotionally tied to
the investments we make. Therefore, since decisions that are
based on emotions are not always in our best interest, thinking
critically about our investments becomes especially important.
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