Mind & Psychology Series

Why Your Brain Lies to You: Three Mental Traps That Sabotage Decisions

We think we are rational, but our minds use shortcuts that often lead to failure. Understanding Survivorship Bias, Confirmation Bias, and Sunk Cost.

We like to think of ourselves as rational human beings. We look at the facts, weigh the pros and cons, and make sensible choices.

Unfortunately, modern psychology tells us that’s often not true. Our brains are designed to be efficient, not perfectly accurate. To save energy, the brain uses "shortcuts" to process information quickly. Most of the time, these shortcuts work fine. But sometimes, they lead us wildly astray, causing us to make irrational decisions with our money, our health, and our relationships.

These errors are called "cognitive biases." Here are three of the most common traps that affect nearly everyone, every day.

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1. Survivorship Bias: The Error of the Visible

Survivorship Bias is the logical error of concentrating on the people or things that "survived" some process and overlooking those that did not. Because the failures are often invisible, we assume the survivors represent the whole picture.

The "Billionaire Dropout" Example

We study the college dropouts who became billionaires (like Gates or Zuckerberg) and conclude that dropping out is a good strategy. The Logical Error: We ignore the thousands of students who dropped out with similar ambition but ended up in debt or unemployed. To understand success, you must also study failure to see what the winners did differently.

The Missing Bullet Holes (The Classic WWII Example)

During World War II, the military analyzed planes coming back from battle. They saw that the returning planes were covered in bullet holes on the wings and tail. They decided to reinforce those areas with more armor.

However, a statistician named Abraham Wald stopped them. He argued they were looking at the survivors. The planes hit in the wings came back; the planes hit in the engine or cockpit never returned. Therefore, the military needed to put armor where there were no bullet holes on the survivors.

Survivorship Bias Plane Diagram

Figure 1: The Wald Diagram. We must protect the areas where the survivors have NO damage, because hits there are fatal.

2. Confirmation Bias: The "I Knew It All Along" Trap

Imagine you have a slight headache. A worrying thought pops into your head: What if this is something serious?

You go to Google and type in your symptoms. The search results show ten links. Nine of them say it’s probably dehydration or tension. One link near the bottom mentions a rare, scary brain condition. Which link do you click first?

If you’re like most people, you click the scary one. Why? Because it matches the fear you already had.

What It Is

Confirmation Bias is the brain’s annoying habit of only paying attention to information that agrees with what you already believe, while ignoring or rejecting anything that challenges those beliefs.

We hate being wrong. It feels uncomfortable physically and mentally. So, our brain subconsciously acts like an overly enthusiastic defense lawyer, filtering out evidence that might prove the "other side" right.

Everyday Examples

  • Politics and News: This is why political arguments at the dinner table are useless. If you dislike a certain politician, you will only tune into news channels that criticize them. If they do something good, your brain dismisses it as a "stunt." If they do something bad, your brain says, "Aha! See? I knew they were terrible." You aren't getting informed; you are getting validated.
  • First Impressions: If you meet someone and decide you don't like them within the first minute, your brain will spend the rest of the conversation looking for reasons to justify that dislike, ignoring their good points.

The Danger: Confirmation bias creates "echo chambers." If you only ever listen to people who agree with you, you stop learning and you become overconfident in your own opinions, even when they are wrong.

How to Beat It: The next time you feel absolutely certain about something, stop and ask yourself: "If I were wrong, what would the evidence look like?" Actively look for information that proves you wrong. It hurts, but it’s how you get smarter.

Confirmation Bias Illustration

Figure 2: Filtering Reality. The brain blocks out facts (circles) that don't fit our square beliefs.

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3. The Sunk Cost Fallacy: The "Throwing Good Money After Bad" Trap

Imagine you paid $20 for a movie ticket. Forty minutes into the film, you realize it is the worst movie you have ever seen. You are bored and frustrated.

Do you walk out of the theater? Most people stay. Their reasoning is: "Well, I already paid $20. If I leave now, I waste that money."

What It Is

This is the Sunk Cost Fallacy. It is the mistake of continuing a behavior or endeavor just because you have already invested time, money, or effort into it—even when continuing will only make things worse.

A "sunk cost" is a cost that has already been paid and cannot be recovered. That $20 for the ticket is gone whether you stay or leave. By staying, you are not "saving" the money; you are just adding wasted time on top of wasted money.

Everyday Examples

  • The Money Pit Car: You have an old car that keeps breaking down. You just spent $1,000 fixing the transmission. Two weeks later, the engine dies, and it will cost another $2,000 to fix. You think, "I have to fix it, otherwise I wasted that $1,000 on the transmission last month!" In reality, you should probably cut your losses and buy a reliable car, rather than pouring more money into a bottomless pit.
  • Bad Relationships or Jobs: People stay in miserable relationships or dead-end jobs for years simply because they’ve "already put so much time into it." They are letting their past investment destroy their future happiness.
  • Overeating: Eating the rest of a meal even though you are stuffed, just because you paid for it and "don't want it to go to waste." (Your body is not a trash can—the food is wasted anyway).

The Danger: The Sunk Cost Fallacy chains you to your past mistakes. It stops you from quitting things that aren't working, causing you to lose even more time and money in the future.

How to Beat It: Forget the past. It’s gone. Ask yourself this magical question: "If I had not already invested time/money in this, would I still start doing it today?" If the answer is no, then cut your losses and walk away.

The Takeaway

Our brains are wired to protect our egos (Confirmation Bias) and to hate losing things we already have (Sunk Cost Fallacy). These instincts were probably useful for survival thousands of years ago, but in the modern world, they often lead to bad choices.

You can’t turn these biases off completely, but you can become aware of them. The next time you find yourself ignoring facts you don't like, or sticking with a bad situation just because it's familiar, pause. That’s just your brain trying to take a lazy shortcut. Don't let it.

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