How Smart Are You?
Five cognitive biases we all fall for

We’re all perceptive. We can think for ourselves, and for that matter, think clearly. Or can we?
Our brains can do a lot, but they’re prone to errors — and not just when we’re tired. When we feel alert and sharp, we can still make bad decisions. What gives?
Our minds can all succumb to cognitive bias, or an error in thinking. Learning to recognize these biases can help you avoid them in the future. Here are five you may have come across, and how to combat them.
1. The halo effect
Say you meet someone at a party, and he shakes your hand and makes friendly conversation. You leave with the impression that he’s a good person, kind and trustworthy.
Then you meet someone else, who seems distant. You might think he’s cold, rude, or shifty.
You’ve fallen into the trap of the halo effect, in which we make broad assumptions (knowingly or unknowingly) about someone based on a little information we know.
For example, when we meet someone we consider attractive, we may also assume that they’re intelligent and kind. This type of thinking can lead to attractive people doing better in performance reviews, even if other people worked harder.
To combat this, try to get to know a person better before making assumptions. A friendly person may not always have your best interests at heart; similarly, a shy person could be very trustworthy and honest.
2. The backfire effect
Imagine you’re talking to someone who believes that the sky is yellow. You begin arguing with them that they’re incorrect, but they won’t budge. To prove your point, you present them with a study that shows that the sky is, in fact, blue.
Rather than accept your point, the person becomes even more steadfast, arguing that this only proves their point that the sky really is yellow, and everyone else is trying to cover it up. What gives?
What you’re seeing here is the backfire effect, in which presenting evidence against someone’s claim actually makes them feel more correct. It’s common in political arguments.
When someone strongly holds a belief, to the point where it’s part of their identity, it’s hard to shake it. In the face of doubt, people will often build up a mental wall around their belief, rather than admit they’ve been wrong the whole time.
To prevent the backfire effect, try to keep an open mind. We aren’t always going to be correct, so evaluate new information carefully. If someone’s trying to persuade you of something, think about their side and what is making them believe what they do.
And if you see someone showing signs of the backfire effect in an argument, understand that they have a strongly held belief, and it’ll be extremely difficult to try to change their mind.
3. The Diderot effect
Also known as the “hedonic treadmill,” this occurs when we buy something, which leads us to want to buy something else, and so on.
Basically, it’s If You Give a Mouse a Cookie, but with shopping.
This effect is named for a philosopher, Denis Diderot, who started buying new possessions to upgrade his lifestyle and went on a spending spree.
To avoid this: Think about why you’re making purchases. Buy clothes that go with what you already have, for instance, instead of ones that will require more items to match them.
If you get a sudden windfall or increase in income, you may be tempted to scale up your lifestyle. In some cases, it’s worth investing in new purchases. However, don’t do so just because money is burning a hole in your pocket — or because of the Diderot effect.
4. The sunk cost fallacy
The sunk cost fallacy can happen in business, relationships, or daily personal decisions. A classic example is an old car. If you spend $1,000 fixing your car, you may be reluctant to sell it later on, because you’ve put so much money in it — even if selling it might be a good decision.
Or maybe you’re in a job you hate. You know you could probably find a better job elsewhere … but you already know everyone at this job. You’ve spent a lot of time there. It would be throwing all that effort away to work somewhere else, right?
To counter this, think about what you’d do if you hadn’t spent any past effort or money on your situation. If the item was a gift, or you had just started the job, would you still keep it?
When we’re in a hole, the best thing to do is stop digging. Don’t worry about the past, but think about the future.
5. The Einstellung effect
The Einstellung effect occurs when people who are newly encountering a problem can solve it easier than experts.
You’ve seen this effect in movies when the experts are scratching their heads trying to solve a problem, and a newcomer breezes in and immediately offers a solution.
This can be a problem in areas like healthcare, where “This is how we’ve always done it” attitudes can keep people from seeing new solutions to problems.
In the biography Elon Musk: Tesla, SpaceX, and the Quest for a Fantastic Future by Ashlee Vance, there’s an anecdote in which a young Elon Musk presents a way for a bank to make money. They refuse; they’re set in their ways, doing things that always worked for them. And they kept on doing the same things, while Musk went on to help create PayPal.
Why is this the case? When we’ve been doing something a long time, we tend to stick with what works, and use mental shortcuts. An outsider has to grasp everything individually, and can see what insiders can’t. They see the individual trees, not the forest, and so they can more easily blaze a trail through it.
As you can see, our minds aren’t always perfectly rational. But when we make errors, we often do so in patterns. The next time you see a cognitive bias, you can identify it and try to work around it.