What is mental accounting?
Richard Thaler's definition of mental accounting has three parts. Each has been tested separately, and a 2025 replication supported eleven of seventeen classic problems.
Answer to the question
What is mental accounting?
Mental accounting is the set of habits people use to organise, evaluate and keep track of money, an idea developed by Richard Thaler. It has three parts: how outcomes are weighed, which account a sum is filed in, and how often accounts are checked. Each part departs from the assumption that money is fungible.
Key takeaways
- Thaler (1999) describes mental accounting in three parts: how outcomes are perceived and weighed, which account a sum is filed in, and how often accounts are checked and how widely they are drawn.
- Thaler (1985) added transaction utility, the pleasure or sting of a deal apart from the worth of the goods, to prospect theory's coding of gains and losses.
- Hastings and Shapiro (2013) found that households moved to lower octane petrol by more than a fall in spending power explains, which counts against treating petrol money as interchangeable with other income.
- Thaler, Tversky, Kahneman and Schwartz (1997) found that participants who evaluated their investments less often took more risk, and those with the most frequent feedback took the least risk and earned the least.
- Li and Feldman (2025) re-ran 17 problems from Thaler (1999) with 1,007 participants: 11 were clearly supported, 3 mixed and 3 not supported. The lost ticket effect shrank, from 88 and 46 per cent to 90 and 77 per cent, and the calculator problem did not replicate.
Richard Thaler named mental accounting in a paper in Marketing Science, and Daniel Kahneman, whose Thinking, Fast and Slow is where many readers first meet the idea, credits him for it. It is the set of habits people use to organise, evaluate and keep track of money.
Each habit departs from a rule economists treat as basic, that money is fungible, meaning a unit of it is worth the same whatever its source or intended use. Thaler's 1999 paper in the Journal of Behavioral Decision Making sets the habits out in three parts. The first concerns how outcomes are perceived and weighed, the second which account a sum is filed in, and the third how often the books are checked and how widely they are drawn. This article takes them in that order, then looks at how the classic demonstrations fared when they were run again.
Thaler's Definition in Three Parts and a Lost Ticket Problem
The first full statement of mental accounting came in a 1985 paper in Marketing Science. It starts from the way the value function of prospect theory codes gains and losses, adds transaction utility, which is the pleasure or sting of a deal as distinct from what the goods are worth, and then brings in household budgeting. The paper closes with implications for pricing. Transaction utility gives a name to the feeling that a good deal is a gain in its own right.
The 1999 paper widened the frame of mental accounting. Its abstract describes income and spending as tagged by source and by purpose, with expenses grouped into categories such as housing or food and sometimes held to a budget. It also describes accounts being checked at different intervals, daily, weekly or yearly, and drawn narrowly or broadly, a feature it calls choice bracketing. The abstract argues that every one of these features breaks fungibility, which is why mental accounting changes the choices people make.
Kahneman discusses the best-known demonstration in Thinking, Fast and Slow. It is a pair of problems from Amos Tversky and Kahneman's 1981 paper in Science. In one, a person has lost a ten-dollar ticket to a show and decides whether to buy another. In the other, the person has lost a ten-dollar bill on the way and decides whether to buy a ticket. The money at stake is the same in both. In the original study, 46 per cent would buy a second ticket and 88 per cent would buy a ticket after losing the cash.
The mental accounting reading is that a replacement ticket is charged to the same account as the first one, so the evening seems to cost twenty dollars, while lost cash belongs to no account in particular. Kahneman adds a caution of his own. Regret and frustration are real consequences, and they are themselves shaped by framing, so he questions whether treating the two versions as equivalent is the right standard for calling the difference an error.
Why Petrol Money Is Not Just Money to Households
The strongest field evidence for mental accounting concerns the second part, the filing of money into categories. Household records of petrol purchases gave Justine Hastings and Jesse Shapiro their test, reported in the Quarterly Journal of Economics in 2013. When petrol prices rose, households moved to a lower octane grade by more than the fall in their spending power could explain. The authors reject the idea that money set aside for petrol is interchangeable with the rest of a household's income, and report that a model in which spending is governed by a budget for the category fitted the data well.
A household can treat money for petrol as a separate pot, and its purchase records show it.
That result comes from what people bought, not from what they said they would do in a survey. The wider evidence from purchase records, including coupons, labelled budgets and food benefits, is audited in our earlier piece [Mental Accounting and the Easy Money](https://thewhyweproject.com/articles/mental-accounting-and-the-easy-money), which also covers the cases that point the other way.
Checking the Books Too Often Changes Risk-Taking
The third part has its own experiment. Thaler, Tversky, Kahneman and Alan Schwartz tested myopic loss aversion in a 1997 paper in the Quarterly Journal of Economics. The term covers a stronger reaction to losses than to gains combined with frequent evaluation of results. Two predictions were supported in a task where participants learned from experience. Those who evaluated their investments less often accepted more risk, and so did those whose payoffs were raised enough to remove losses. The participants who received the most frequent feedback took the least risk and earned the least money.
The width of the account matters as well as its timing. Treating each decision as a separate account is the territory of [narrow framing](https://thewhyweproject.com/articles/what-is-narrow-framing), and the sunk cost fallacy, which Kahneman derives from mental accounting, is a case where an earlier outlay keeps an account open. Our piece on [the sunk cost fallacy](https://thewhyweproject.com/articles/what-is-the-sunk-cost-fallacy) takes that case on its own.
Seventeen Classic Problems, Run Again in 2025
A registered replication in Royal Society Open Science put seventeen mental accounting problems from Thaler's 1999 review back to the test in 2025. Mengfei Li and Gilad Feldman ran them on 1,007 participants recruited online in the United States, roughly 500 per problem. Eleven were clearly supported, three received mixed support and three received none. Four predictions that had never been tested were added, of which two were supported, one was mixed and one was not.
The two problems above fared differently. The lost ticket effect replicated, though much smaller: 90 per cent of those who had lost cash bought a ticket, against 77 per cent of those who had lost the ticket. The calculator problem did not replicate. In the original, 68 per cent would travel to another store to save five dollars on a cheap item and 29 per cent on an expensive one. In the replication the figures were 11 and 7 per cent, with no meaningful difference between conditions.
Taken part by part, the evidence for mental accounting is firmer than it is taken whole: it is strongest where one component of Thaler's definition is tested at a time, and weakest where one vivid problem is asked to stand for the lot. Sorting money is not in itself a mistake, and Kahneman's own caution about regret applies to every one of these problems. What the research tests is whether a particular boundary, such as a ticket, a petrol budget or a reporting interval, changes what people choose, and where the evidence is strongest it has changed choices in purchase records as well as in surveys.
Common questions
What is mental accounting?
Mental accounting is the set of habits people use to organise, evaluate and keep track of money. Richard Thaler described it as having three parts: how outcomes are perceived and weighed, which account a sum is filed in, and how often accounts are checked. Each part breaks the assumption that money is fungible.
Who came up with mental accounting?
Richard Thaler developed the idea, with a 1985 paper in Marketing Science and a 1999 review in the Journal of Behavioral Decision Making. Daniel Kahneman and Amos Tversky's framing problems supplied some of its best-known demonstrations, and Kahneman credits Thaler for the idea in Thinking, Fast and Slow.
Is mental accounting irrational?
The research does not settle it. The same people who treat a lost ticket and lost cash differently may be reacting to real regret, as Kahneman notes. A 2025 replication supported eleven of seventeen classic problems, including a smaller lost ticket effect, and did not support the calculator problem.
Sources
Kahneman, D. (2011). Thinking, Fast and Slow. New York: Farrar, Straus and Giroux. Seed book; vault hub Books/Thinking Fast and Slow.
Thaler, R. (1985). “Mental accounting and consumer choice.” Marketing Science, 4(3), 199-214. doi:10.1287/mksc.4.3.199 https://doi.org/10.1287/mksc.4.3.199
Thaler, R. H. (1999). “Mental accounting matters.” Journal of Behavioral Decision Making, 12(3), 183-206. doi:10.1002/(SICI)1099-0771(199909)12:3<183::AID-BDM318>3.0.CO;2-F https://doi.org/10.1002/(SICI)1099-0771(199909)12:3<183::AID-BDM318>3.0.CO;2-F
Tversky, A., & Kahneman, D. (1981). “The framing of decisions and the psychology of choice.” Science, 211(4481), 453-458. doi:10.1126/science.7455683 https://doi.org/10.1126/science.7455683
Hastings, J. S., & Shapiro, J. M. (2013). “Fungibility and consumer choice: Evidence from commodity price shocks.” The Quarterly Journal of Economics, 128(4), 1449-1498. doi:10.1093/qje/qjt018 https://doi.org/10.1093/qje/qjt018
Thaler, R. H., Tversky, A., Kahneman, D., & Schwartz, A. (1997). “The effect of myopia and loss aversion on risk taking: An experimental test.” Quarterly Journal of Economics, 112(2), 647-661. doi:10.1162/003355397555226 https://doi.org/10.1162/003355397555226
Li, M., & Feldman, G. (2025). “Revisiting mental accounting classic paradigms: Replication Registered Report of the problems reviewed in Thaler (1999).” Royal Society Open Science, 12(9). doi:10.1098/rsos.250979 https://doi.org/10.1098/rsos.250979