What could possibly be wrong with well earned praise? We all know how nice it is to receive a pat on the back for a job well done. Plus, study after study shows employees generally feel under-appreciated and are less productive than they could be because of a shortage of praise.

The obvious benefits of praise lead many well meaning managers to compliment their team members with things like, "Your presentation was the best!" or "You made the most valuable contribution to that project!"

But as bestselling author and Oprah-anointed happiness expert Shawn Achor pointed out on in an excerpt from his new book on the TED Ideas blog recently, that sort of praise -- well intentioned as it might be -- actually does more harm than good. What's wrong with it? Just three little letters: E, S, T.

The problem with superlatives

Achor certainly has no problem with praise in general. In fact, he's a big advocate for leaders doling out hefty portions of gratitude. "When done right, praise primes the brain for higher performance, which means that the more we praise, the more success we create. And the more successes there are, the more there is to praise," he writes.

But that depends on the praise being "done right." And if you're using superlative language like, "the best" or "the smartest," you're not doing it right. Why? Because that isn't praise, that's comparison, and as such it sets up implicit competition with others, which tends to make people more stressed and self-aware.

"The worst piece of praise I've sometimes received after a talk is 'You were the best speaker today,'" insists Achor. This sounds nice but really it just "reminds me of the fact that in many other cases I won't be the best speaker, so now I feel nervous and self-conscious," he continues.

While a healthy rivalry with teammates or competitors can sometimes spur people on in specific situations, in general being acutely aware of your performance is a pretty surefire way to undermine it, according to science. Every moment you're stressing about whether you're better than the girl in the next cubicle over is a moment you're not focused on thinking creatively, serving your customers, or producing delightful work.

Also, when you praise one employee at another's expense, you're lifting someone up with one hand, but swatting someone else down with another, resulting in a net draw when it comes to team motivation.

Finally, and perhaps most counterintuitively, Achor points out that comparison dressed up as praise actually also sets a low bar for excellence. All you have to do to earn a compliment is shine slightly brighter than the next guy. An employee's potential may be much greater than that.

"By telling someone they are 'better' or 'the best,' you are placing an unconscious, implicit limit on your expectation for what they can achieve. If we're striving only to be better than someone else, doesn't that set our expectations for ourselves too low? It tells us that as soon as we are just a little bit better than another person, we can stop trying, even if it means stopping short of our potential," Achor notes.

Instead, of setting up rivalries and stoking insecurities by using superlatives in your praise, Anchor recommends making specific, honest observations about what your people do well. "Real praise is telling someone 'Your report was amazing,' or 'The comedic timing of your speech was perfect,' not telling them that their report or their speech was better than another person's," Achor instructs.

The simplest way to do put this insight into action is just to cut all those '-est' words out of your praise.

This is true at home and school too.

And, Achor notes, this is true at home and school too. "No matter how good your intentions, if you excitedly say to a child 'You were the best one out there!' you just taught them that your love and excitement were predicated on their position compared to others," Achor cautions.

So parents and teachers, remember that next time you are about to unthinkingly tell a kid he or she is "the smartest" or "the funniest." There are far better ways to praise a child.