There are plenty of ways to gain employee compliance--direct orders, insistent nagging, guilt trips--but one technique has been proven to work better than any other: the option to say "no." 

Offering the freedom to decline was a theory originally put forward by two French researchers, Alexandre Pascual and Nicolas Gueguen. They included a simple sentence in a request for money: "but you are free to accept or refuse." Those requests received twice as much as those who directly asked for a donation without a chance to decline.

The technique affirms the ability to say no, weakening "reactance," or the anger and frustration at being told what to do. It's not a surprising outcome: experiences are more enjoyable when there's a level of autonomy involved. It's the difference between "having to" and "wanting to." Psychologists have theorized that having this choice is key for motivation.

Yet the new tool hadn't been fully tested--until this year. C. J. Carpenter analyzed 42 studies of the technique to better understand its efficacy. The results were published in journal Communication Studies. 

Carpenter found that the technique gets results faster and is just as (if not more) effective than other compliance-gaining schemes. And, perhaps more importantly, it can be used in a multitude of contexts, including charitable, prosocial, and selfish requests. You can use it to ask for a donation to feed starving children or to ask for a cup of coffee.

The only flaw is the requirement of a physical presence; it won't work as well through email or letters. One reason may be that the worker would feel less social pressure for the technique to work. 

If you've been having trouble getting employees to comply, it may be time to try offering them the freedom to decline ... but only if you want to.