Mental Accounting
Why does someone who agonizes at a convenience store to save about $74 of their paycheck spend about $74 of New Year's gift money in a single day? Even though it's the same amount. The concept that explains this strange mind is 'mental accounting.'
What Is Mental Accounting?
Mental accounting refers to the psychological phenomenon in which people manage money in different mental 'accounts' according to its source or use, and spend or judge based on each individual account rather than on their total wealth.
It's a concept organized by behavioral economist Richard Thaler, who systematized it in his 1999 paper 'Mental Accounting Matters' and won the Nobel Prize in Economics in 2017.
A basic assumption of economics is that 'money has no label.' It means that about $74 is the same about $74 no matter where it came from or where it's spent. This is called 'fungibility.' Yet in our heads, each piece of money carries a different label, so this principle is often broken.
Thaler is cited as the first to propose mental accounting, but his claim isn't a guideline of 'do this'; it's an observation that 'people actually behave this way.' He in fact recommended treating all money the same.
Why Does Free Money Vanish So Easily (the House-Money Effect)?
New Year's gift money, holiday allowances, tax refunds, bonuses, lottery winnings. Money that appears unexpectedly like this is often called a 'windfall.'
People tend to put a windfall not into 'my own money' but into a separate mental account as 'money that came as a bonus.' So they open their wallets easily even in places where they'd normally be too reluctant to spend. A tax refund is actually 'my money' — you're getting back tax you overpaid in advance — yet it's a prime case of being spent as if it were money that appeared for free.
The tendency to spend money obtained for free (or already earned) more loosely and to take on more risk with it is called the 'house-money effect.' The name comes from the way money won at a casino feels like the 'house's (casino's) money,' so it's easily bet again.
The house-money effect has been observed in various experiments, but some follow-up studies dispute its replicability. It's more accurate to understand it as 'there's such a tendency' than 'it's always so.'
The Traps Mental Accounting Creates in Investing
Mental accounting sways our judgment in investing too. Let's look at a few common scenes.
First, treating dividends and capital gains differently. Though it's the same profit, you split dividends into 'spending money that's okay to use' and principal and capital gains into 'money you mustn't touch,' so when you receive a dividend you spend it, not even realizing your assets went down.
Second, separating principal from gains. Reasoning 'the profit portion is money I earned anyway,' you take excessive risk only with that portion. But to the market, whether principal or gains, it's all equally just your money.
Third, leaving a loss account aside. You put a deeply underwater stock into a separate account you 'pretend doesn't exist,' and, unwilling to realize the loss, you hold it for a long time without even being able to sell. At this point you end up ignoring the truly important maximum drawdown (MDD) and drawdown (loss) duration.
Money has no label. A $37 dividend, a $37 capital gain, and $37 of salary are all part of the same total of about $110. You must view it from the standpoint of total assets so your judgment doesn't get clouded.
Turning Mental Accounting to Your Advantage
Mental accounting isn't always a bad thing. If you know this human nature, you can actually use it to build good habits.
For example, the method of automatically setting money aside into an 'investment account' first when your paycheck comes in makes you classify that money in your mind as an 'account you mustn't spend,' which helps protect your saving and investing. Thaler himself viewed mental accounting positively as a 'self-control device' of this kind.
The key is the difference between 'being unconsciously swayed' and 'consciously designing.' When a windfall appears, instead of spending it on impulse reasoning 'it's a bonus anyway,' the habit of pausing once to think 'this too is part of my total assets.' That small pause separates the long-term investor from the one who isn't.
Preguntas frecuentes
Q. Is mental accounting unconditionally bad?
No. When you're swayed on impulse, it leads to losses, but when you design it consciously, it becomes a good tool. The habit of setting investment money aside first from your paycheck into an 'account you don't touch' helps protect saving and long-term investing. The problem isn't dividing into accounts itself; it's deciding irrationally by looking only at a particular account without seeing your total assets.
Q. Why should I be careful with dividends?
When you receive a dividend, it feels like allowance that appeared for free, so you spend it easily. But a dividend is a company distributing accumulated profits to shareholders, so the share price usually adjusts by that much on the ex-dividend date. In other words, a dividend may not be 'money that appeared additionally' but money that was already part of your assets. Whether capital gains or dividends, you must view them together from the standpoint of total assets so you don't fall into an illusion.
Q. What exactly is the 'house-money effect'?
It refers to the tendency to take on more risk than usual and spend more loosely with money obtained for free or gained unexpectedly. It originates from treating money won at a casino as the 'house's money' and easily betting it again. In investing, it often appears as taking reckless risk with the profit portion already earned, ultimately shaking even the principal.
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