Predictably Irrational · Dan Ariely

Predictably irrational examples

Curated by · reviewed 2026-05-30

We don't err randomly — we make the same illogical mistakes in consistent, predictable ways. Knowing the patterns lets you design around your own quirks.

What is predictably irrational? Read the full idea →

5 examples of predictably irrational

  1. The power of FREE

    People grab a worse free item over a better cheap one, every time — irrational, but predictably so.

  2. The decoy option

    Adding a deliberately bad third choice reliably pushes people to the pricey one.

  3. Relativity in pricing

    We can't judge value in isolation, so a 'compared to' anchor predictably sways us.

  4. Ariely's experiments

    Across thousands of people, the irrational choice repeats — which means it can be anticipated.

  5. The pain of paying

    An all-inclusive resort feels better than itemised bills, because we predictably hate each separate sting.

How to spot it in yourself

You'll forget most of this by next week.

That's just how memory works. Lock predictably irrational in with a 5-minute active-recall session — spaced repetition, no signup.

Try this idea free →

One tap adds it to your review queue — we bring it back right before you'd forget.

Related ideas