We all make money mistakes from time to time. Much of the time, we are vaguely aware that we are making a mistake, or it is even obviously an error the moment we make it. But the science of behavioral economics is showing just how subtle these things can be. Are you making either of the following money mistakes?

Money Mistake - Mental Accounting

A term used by researchers in the field of behavioral economics, mental accounting refers to how we treat money from different sources differently. For example, if you work hard to save $2,000, you might be very careful in how you spend it, while a $2,000 tax refund - which seems like a lottery win - might be treated as less important. Of course, the amount is the same, and you are free to use it any way you choose, but a "windfall" is typically treated differently from earned income.

I used to see extreme examples of this when I dealt blackjack in a casino years ago. Most players had a mental category they called "house money." This was the profit that they had made, or at least the amount that they were ahead at the time. A man might be very cautious betting with his "own" $200 bankroll, but once he had $600 of winnings in front of him, he would start betting more and playing with less caution. "I'm playing with "house money" he would announce.

Of course, the reality is that once he won the money in the first place, it was all his money. He was free to walk out that door and do anything he wanted with the $600 profit. In fact, he would might stop before he ever lost $600 of "his own" money, but this was somehow different. The result was predictable. If some common sense prevailed, he might lose only $500 of it, and still leave with more than he started with. More often, he would lose the $600 AND the $200 he brought.

You might think that this is not a problem you have. But what if you won $1,000 on a lottery ticket, or got a $1,000 bonus from your employer. You could take your windfall and put it into your retirement account or your child's college fund. But do you really treat such money the same as if you worked weekends to make an extra thousand? This is an easy money mistake to make.

Money Mistake - Integrating Losses

This is another tough one to avoid. When you buy that new car, do you suddenly feel like an extra $300 for a better car stereo isn't much money? Of course, it doesn't seem like much when you are spending $22,000 for a car - and that's why that salesman will push these things. But if it isn't too much, why did it seem like a lot to buy such a stereo for your previous car. Just the day before you might have thought $200 was too much.

This is about the psychology of making large purchases or taking large losses. This is another classic habit you see in gamblers. $100 was too much to lose at the start of the night, but once he is suckered into losing $2,000, it seems easier to throw that last $100 out there all at once. This is not a phenomenon limited to gamblers or new car buyers, however.

Suppose you are having a new house built. The builder gets you all excited about the latest refrigerator, which he can include for only $3,000 extra. The day before, that same refrigerator might have been worth just $1,800 maximum to you. In fact, you might buy one for just $1,500 if you wait until you move into the home. But when you are spending (or borrowing) $300,000 to have a home built, $3,000 just doesn't seem so outrageous.

You have to mentally step outside of the situation for a moment to avoid making this money mistake. Ask yourself if the proposed expenditure is one you would have felt good with a week ago. Ask what other options you have. Finally, just wait. A month later - after a large purchase - you might be in a more rational state of mind to decide what something is worth to you.