Duncan Ville

Another downside of our silence about money is that we become even more likely to make financial decisions based on emotion rather than on logic or research. In Why Smart People Make Big Money Mistakes (Simon & Schuster, 1999), a terrific book that I recommend to all my friends and clients, journalist Gary Belsky and psychologist Thomas Gilovich summarize a new branch of economic research, called behavioral economics, that examines many of the most common traps that lead us to make poor money decisions.
Let me give you just a few examples. If you tend to treat your hard-earned income differently from the way you treat other money—say a tax refund or a lottery winning—you’re guilty of what behavioral economists call mental accounting. This concept, developed by Richard Thaler of the University of Chicago, describes our tendency to categorize and value our money according to its source or how we spend it. Mental accounting can be dangerous, because in reality one dollar is worth just as much as the next. One hundred dollars that you get from a windfall will buy you just as much as one hundred dollars you’ve saved. Likewise, if you feel much freer spending money when you use a credit card than when you pay in hard cash, you are likely practicing a form of mental accounting.
There’s also what the behaviorists call the “sunk-cost fallacy.” If you’re the type who continues to pour money into an old rattletrap, you should train and discipline yourself to think hard before you throw any more good money after bad. If you wouldn’t want to buy the car today, knowing that it needs repairs, why would you want to waste money fixing it up just because you already own it?