10 Mental Traps That Sabotage You Without You Even Noticing (II)
Distilling books - Number 10
Welcome to Mental Garden. The following letter is part of our “Distilling Books” collection, in which we extract the most revealing ideas from literature. For the complete library, click here.
🏷️ Categories: Behavior, Decision making and biases.
Did you land here by chance?
If you haven’t read the first part of this journey through 10 mental traps that sabotage your decisions (by the brilliant Dan Ariely), do yourself a favor and start there.
👉 Click here to read the first part
In that piece, we explored how context distorts your perception, how prices can anchor your thinking, why “free” disarms you, and how your environment affects your ability to reason. This is the second half of the journey.
Let’s continue the adventure…
6. Procrastination is a bad strategy
We all procrastinate. The problem is thinking we do it because we’re lazy.
Nope. We do it because we haven’t designed systems to help us avoid it, and so we fall prey to instant gratification. To prove his theory, Ariely divided his students into three groups for a simple experiment.
6.1. The deadline experiment
No deadlines: This group had full flexibility; they just had to submit three papers by the final day of class.
Self-imposed deadlines: Students chose their own deadlines. Each day late would deduct 1% from their grade.
Externally imposed deadlines: Ariely gave this group three firm deadlines, evenly spaced throughout the semester.
Result? Group 3 scored the highest grades.
Less freedom, less self-deception: While self-imposed deadlines helped, externally imposed ones worked better. Many students failed to space their work well, which hurt the quality.
Parkinson’s Law: Work expands to fill the time available. If you have two weeks, you’ll take two weeks. If you have two days, you’ll do it in two days.
Design your calendar as if you don’t trust yourself — that’s exactly what will save you.
7. You overvalue what’s yours
Someone gives you a mug. The next day, someone offers to buy it. You refuse — unless they pay a small fortune. But if you saw that same mug in a store… you wouldn’t buy it.
That’s the endowment effect.
7.1. The Basketball Ticket Case
Ariely observed a real-world case and decided to test the psychological theory...
At Duke University, there’s a deep passion for the basketball team. Tickets are extremely coveted — so much so that front-row seats are distributed via lottery; you can’t even buy them directly.
He wanted to see whether students who won tickets (i.e., gained ownership through the lottery) would value them more than those who didn’t.
They called students who had won tickets and asked how much they'd be willing to sell them for.
Then they called students who hadn’t won, asking how much they’d pay to buy one.
Result? If it’s mine, it’s worth millions.
Students who didn’t win were willing to pay an average of $170. They mentioned other ways to spend the money, like watching the game in a sports bar and saving the rest.
Students who did win demanded an average of $2,400 to sell. They justified it with the experience’s importance, the memories it would create, and the uniqueness of being there.
The mere feeling of “owning” something multiplies its perceived value tenfold.
Don’t ask how much something is worth.
Ask if you’d value it the same if it weren’t yours.
8. Loss Aversion Controls You
We’d rather avoid losses than gain equivalent rewards.
8.1. The Virtual Doors Experiment
Simple game: Participants played a computer game where they had to click on doors (red, blue, or green) to earn money. Each click inside a door gave a small monetary reward. The more clicks, the more money.
The only rule: If a door wasn’t visited within a certain number of clicks, it would disappear.
Goal: Maximize total clicks (i.e., money).
Result?
Most participants wasted a lot of clicks trying to keep all the doors open.
Yet they all admitted they’d realized each door gave the same payout per click.
In other words, they could’ve focused on just one door and made more money.
But the urge to keep their options open cost them.
That’s loss aversion: the irrational fear of losing options hurts so much that we’d rather keep all of them — even if that means real losses.
That’s the price of not choosing: you lose time, money, and focus.
Moral: Learn to say “no.” Set limits. It’s incredibly powerful.
9. Your Expectations Shape Your Reality
Ever noticed how something tastes better just because it’s more expensive?
Ariely did a beer experiment to prove the power of expectations.
9.1. The Beer Experiment
He offered people two beers: One was a classic Budweiser. The other, the “MIT Brew,” had a secret ingredient added: balsamic vinegar.
Three groups:
No info: This group tasted both beers without knowing anything.
Told beforehand: This group was informed about the vinegar before tasting.
Told afterward: This group was told after tasting.
Result?
When they didn’t know about the vinegar, they preferred the MIT Brew. If they were told beforehand, they rejected it immediately. And if they learned about the vinegar after, they still liked it.
Expectations shape your taste. Same as with the Pygmalion effect.
What you expect to feel changes what you actually feel.
Taste isn’t just on the tongue — it’s in the mind too.
I’ve always heard this from fruit vendors: “People buy with their eyes.” The more I study psychology, the more I understand it. Doesn’t matter if the fruit is good — what matters is that it looks good. Same with vinegar in beer.
Your expectations can ruin an experience — or make it unforgettable.
10. Price Changes the Experience
Dan Ariely proved the placebo effect’s power with shocking simplicity.
He gave participants a supposed painkiller called Veladone-Rx. In reality, it was just vitamin C. He offered the same product at two different prices:
Group 1: Told it cost $2.50 per dose.
Group 2: Told it cost $0.10 per dose.
Result? Exactly what you'd guess.
Those who took the expensive version reported far more pain relief than the low-price group. That’s the power of price: We don’t just pay more when we think something is valuable — we also feel it works better when it’s expensive.
Same goes for quality and performance in products.
Price activates the placebo effect.
Think about how wild that is: Not only did they get vitamin C and believe it was a painkiller — they believed it was better just because it cost more.
That’s how easy it is to convince someone that something is superior.
Now you know: we’re not rational.
Not you. Not me. Not your boss. Not your partner. But the most dangerous thing isn’t being irrational — it’s believing you’re not. The good news? These biases aren’t random. They’re systematic. If you understand them, you can predict them.
And if you can predict them… you can avoid them.
✍️ Your turn: Which of these mental traps has affected you the most?
In my case, I’d say number 9. I’ve often promised myself to approach things without expectations — because when I do have them, they’ve ruined entire experiences for me.💭 Quote of the day: “Our irrational behaviors are neither random nor senseless. They are systematic and predictable.” — Dan Ariely, Predictably Irrational
See you in the next letter! 👋
References 📚
Ariely, Dan (2008). Predictably Irrational, Harper Collins.