Mental Accounting
We treat money differently depending on its source or intended use.
Mental accounting is the set of cognitive operations used by individuals and households to organize, evaluate, and keep track of financial activities. The concept was first described by Richard Thaler. We treat money differently depending on its origin (earned vs. found) and purpose (grocery money vs. gambling money), despite the fact that money is fungible and a dollar is a dollar.
What it looks like in the wild.
- Everyday life Tax Refund Spending People spend tax refunds more freely than identical amounts from their salary because they mentally categorize it as 'found money'.
Someone has already built a business on this.
Biases are not only private errors. They are design targets — patterns deliberately engineered into interfaces because they reliably work.
- Games Virtual Currency Games introduce virtual currency (V-Bucks, Robux) to break the mental accounting connection between real money and in-game purchases, enabling higher spending.
Recognising a definition is not the same skill as spotting it.
Two scenarios from the app, with distractors drawn from the same family of biases — which is what makes them hard.
You get a $75 refund from an overcharged utility bill. You use it to order takeout for two nights in a row. You've been packing the same cheap lunch for work every day to save money.
Sophia finds a $10 bill in a library book. She uses it to buy a premium coffee, but she usually makes coffee at home to save.
Biases rarely arrive alone.
Understand more. Assume less.
188 biases, 18,869 scenarios, and a record of how you actually decide.
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