Why do otherwise smart people sometimes make foolish purchases and fail to save for the future but then also frequently penny-pinch in ways that hurt them? The problem is not necessarily a lack of willpower or a failure to stop and think before making spending ­decisions.

What often happens is that even when we do think before we act, our instincts and emotions steer us wrong again and again. Why? In a nutshell, evolution did not shape the human brain to evaluate things such as retirement accounts and 40%-off sales at stores.

Here is a look at five ways that your normal human instincts and emotions can lead you to make costly money mistakes—and how you can do better…

Trap: You know what you want today, but you have trouble connecting with a version of yourself that will exist many years from now. When psychology researchers ask study subjects to imagine themselves years in the future, the results are startling—the subjects struggle to picture those future selves and feel surprisingly little connection to them.

Example: One study found that the typical person feels less empathy for the 20-years-later version of himself/herself than he feels for a homeless person he sees on the street but never meets. This lack of empathy for our future selves greatly decreases our drive to save for the future.

What to do: Use a free app such as AgingBooth or Oldify (Oldify costs $0.99 for iOS) to age a photo of yourself by 20 years. Spend a minute looking at this aged image before making any major spending or saving decisions (such as filling out 401(k) retirement account contribution forms at work). A 2011 study published in Journal of Marketing Research found that people who look at pictures of their aged selves feel a deeper connection with their future selves and save more money.

Trap: You use past spending decisions as a guide when you make new spending decisions. When we decide whether a product or service is worth its price, we tend to use the financial decisions we have made in the past as reference points, often without realizing we are doing so. So if you ever paid $5 for a coffee…$100 for a pair of jeans…or $60,000 for a car, the odds dramatically increase that you will convince yourself that it is acceptable to do so again. After all, if these weren’t reasonable spending decisions, you wouldn’t have made them the first time—right?

What to do: Unfortunately, most of us already have plenty of overspending lurking in our pasts, ready to inspire overspending in the future. One way to break the cycle is to conduct a more conscious review of your previous spending by reviewing your credit card statements and checkbook (and any other spending records) at the end of each year and asking yourself, Which of these expenditures did not serve me well?

This will make you a better, more objective judge of future spending choices.

Trap: You worry too much about “fairness” when you spend. Imagine that you call a locksmith because you are locked out of your house. He tells you that he can come right away and unlock your door for $150, and you agree. If you’re like most people, you’ll consider this fee acceptable if the locksmith sweats over your lock for two hours…but you’ll feel cheated if he opens it in two minutes. But why? After all, he opened your lock, and he didn’t leave you standing outside for hours as a slow, incompetent locksmith would have.

Or imagine that you’re walking down a city street and it starts raining. As you approach a street vendor to buy an umbrella, you see her increase the price from $10 to $15. Do you feel outrage at this price increase and walk away? What the umbrella previously cost should not be relevant—either it’s worth $15 to you to stay dry or it isn’t.

What to do: If you feel your sense of moral outrage rising when confronted by a price, focus on the benefit that this product or service is providing, not the amount of effort that was required to provide it to you or how much it might have cost under different circumstances. And view quick work done for you as a positive—tell yourself, Wow, he not only got the job done, he also saved me time.

Trap: You think there’s no downside when you hear the word “free.” One day each year, Ben & Jerry’s gives out free ice-cream cones, and many people stand in line for a half hour or longer to get a snack that they could have purchased for $4 on any other day with barely any wait. This values their time at below the hourly minimum wage.

Similarly, when people are asked to choose between a 99-cent app that does something very well and a free app that does that same thing much less well and perhaps requires more time and/or effort, most people will choose the free app—even if the 99-cent app would add much more than 99 cents worth of convenience or pleasure to their lives.

When people see the word “free,” they stop thinking in terms of cost/benefit and instead think, This is free—there’s no reason not to. But free things often do have a cost—they can consume time or detract from quality of life.

What to do: When you see that something is “free,” mentally assign a minimal price to it instead, such as a dollar. Ask yourself, Would I go to the trouble of buying/using this if it cost a dollar, or would I pay a slightly larger amount for a different option? Assigning even this very low price tends to encourage our brains to think through the nonmonetary cost of something that’s free rather than get hypnotized by the word “free.”

Trap: You think of your income in the wrong way. When you think of your annual income, which might be a relatively large number, you may feel pretty well-off…which makes you more likely to overspend.

At the other end of the spectrum, when you think of your income on, say, a per-hour or per-day after-tax basis, which is a much smaller figure, you are more likely to feel poorer…which makes you think that you don’t have enough room in your budget to save for the future.

What to do: When you are about to make any sort of choice between saving and spending, reflect on your annual income. But before spending money, think about how much you earn after taxes on a per-hour or per-day basis.

If you’re already retired, before making a purchase, think in terms of your monthly, weekly or daily budget. You’ll make wiser decisions!