When it comes to influencing employee behavior, there's no need for evil, head-shrinking, black magic.

Simple things like getting your employees to put money into a 401(k) program can be accomplished with a simple brain hack. If you make the program opt-in, few employees will utilize it. But make the plan opt-out, as many companies have done, and more employees will stick with it.

This is an example of a method of influencing behavior that harnesses the power of sloth, or laziness.

When it comes down to it, influencing people to take a certain action is simple. "If we want to influence other people's behavior, we must make desirable behaviors easy and undesirable behaviors hard," Art Markman, a professor of psychology and marketing at the University of Texas and author of Smart Thinking, writes in Harvard Business Review.

Markman says this school of thought is based on Richard Thaler's and Cass Sunstein's book Nudge. "The human cognitive system aims to get the best possible outcome for the least possible energy cost," he explains.

When it comes to decision making, the old school of thought was that information spurred decisions. While that is true, Markman says, a better explanation is that energy "is the key currency that the cognitive system seeks to preserve."

Markman explains that the brain is only 3 percent of a person's body weight, but it uses up to a quarter of a person's daily energy supply. This is where the key to influence for many decisions lies: Humans need energy to think and keep the brain functioning. The time a person spends on thinking about a decision is commensurate with the amount of energy the brain uses to make that decision.

So if you want someone to make a certain decision, you should make it easier for them to do so. In short, people are lazy.

"People want to minimize the amount of time and brain energy they spend thinking about a choice and also minimize the amount of time and bodily energy they expend toward carrying out actions after the choice is made," Markman says. When people are completing day-to-day actions, they are using the least amount of thought possible.

Retail and grocery stores use this type of psychological marketing on their customers. Impulse purchases like gum, candy, and magazines are usually right next to the cash register. "You're not spontaneously purchasing those items because you have more information about those non-necessary products, but on the basis of a combination of what the environment makes easy to do, the habits people have learned from past actions, and the results of previous deliberations about a decision," he writes.

The same method the opt-out 401(k) program uses can be used for other initiatives. If you want your employees to start working at 7 a.m., have your office doors unlock right at 7 a.m. To get them to leave by 6 p.m., program the computers to give a 15-minute warning at 5:45 p.m. and schedule the air conditioning system to turn off at 6.

"This orientation to the environment can change or reinforce all kinds of behaviors," Markman says. To curb the number of smokers in the United States, for example, a public health campaign outlawed smoking in offices, restaurants, airplanes, and trains. Today, only 20 percent of U.S. citizens smoke, compared with 50 percent in 1960.