We all lie or cheat from time to time; anyone who tells you they don’t, well, they’re probably lying. It could be as simple as embellishing an expense report a little, helping yourself to a few more free samples than you know you should take, or using a little “creative accounting” at tax time.

Though most of us think of ourselves as basically good and honest, research has shown time and time again, even honest people will cheat if the circumstances seem right.

But that doesn’t mean that potential cheaters can’t be set straight or motivated to do the right thing. Here’s a look at what research has found about why we cheat and how to prevent it.

Cheating can be contagious and a slippery slope

There are as many reasons why people will sometimes cheat. When we are sleep-deprived or exhausted from previous tasks, we are more inclined to look for an easier way, even if it means cheating.

When we think there’s lots to go round, we can also rationalize stealing a little bit, thinking no one will care -- a phenomenon known as the “abundance effect.”

There’s also “the broken window effect” of cheating -- the idea that when we see others violating a certain rule, we are more likely to violate it too.

Researchers did a few experiments to show that phenomenon, including one in a parking lot with prominent signs saying it was prohibited to lock bikes to a certain fence, and another calling for the use of a detour around the fence because entry was forbidden.

When bicycles were placed far from the fence, just 27 per cent of people disobeyed the detour sign and squeezed through the gap in the fence. But when bikes were locked to the fence, 82 per cent of people squeezed through the gap -- seemingly believing that if others were breaking the one rule, they could break the other one too.

So, in effect, cheating can be contagious.

Discouraging cheating

So it's clear why we don't want cheating to be seen as somehow "okay" in our businesses, our classrooms, or even within our families. So what can be done to prevent it?

One method that has surprisingly effective results is called the reminder effect. Reminding people that cheating is wrong actually seems to motivate them not to cheat.

Several key researchers in behaviour economics tested this idea using more than 13,000 U.S. auto insurance policy forms. Participants were asked to report how much mileage their car had, knowing that less mileage would mean lower insurance premiums.

Customers who were told to sign a box at the beginning of the form asking them to attest to the truthfulness of the information tended to report higher mileage than those who signed a similar box at the end, when presumably their decision to fudge the numbers had already been made. When people are asked to promise they will be truthful early on, however, it activates their moral sense, making it harder for them to cheat later.

Dan Ariely, one of the researchers on that experiment, wrote a book called “Predictably Irrational,” in which he describes similar experiments he’s led. One of those found that getting people to recite the Ten Commandments before they took a test drastically reduced the chances that people would cheat. Even those who said they were atheists cheated less if they were asked to swear on a Bible.

Ariely says it’s not the fear of God that stops people from cheating; it’s merely being reminded of acceptable moral standards that sets them on the right path. (More on this from one of Ariely’s TED talks.)

Other times, cheating occurs because people don’t quite understand the rules. One study found that college students who were asked to take an online tutorial on plagiarism tended to plagiarize two-thirds less often than students who did not.

The students said it wasn’t that the tutorial scared them with warnings about punishments on how easy it is to get caught; it was that the video clearly explained what is and isn’t plagiarism, and many said that until then, they had not really understood the rules.

Perhaps the best way to eliminate cheating is to change the stakes. Research has shown that cheating among students is more likely in classrooms that focus on performance -- getting the best possible grades and test scores -- rather than "personal mastery" of the material, meaning truly learning and understanding what is being taught. When students are given cues that good grades are more important than the material itself, they are simply more likely to cheat.

The same idea goes for employees. Research has shown that when employees are told there are certain targets they need to meet in order to earn bonuses or meet performance targets, they are more likely to fudge paperwork and cut corners.

There’s nothing wrong with incentives, the authors of that study conclude; just realize that they can increase the risk for sketchy behaviour. After all, we’re only human.