The approach that I take to giving advice in Good Boss, Bad Boss  and in everything else I write is to try to be as evidence-based as possible. But I also realize that the academic literature does not always map neatly onto the demands and needs of bosses and others in organizations. So I also offer logical or theory-based advice that seems like it is likely to be supported by research--even if that research has not yet been done or I don't know about it. Although most assertions in Good Boss, Bad Boss are grounded directly in evidence from peer reviewed studies, my arguments about the value of saying "thanks" were only indirectly grounded in research on influence, especially on the norm of reciprocity . At least they were it wasn't until I learned of this study  in the Journal of Personality and Social Psychology from co-author Adam Grant. Here is what I wrote at the end of Chapter 3, which focuses on wisdom:
Wise bosses don't just display empathy, compassion, and appreciation through dramatic and memorable gestures, as Dean Plummer did for me. They convey it through tiny and seemingly trivial gestures. As we've seen, effective bosses work their magic by piling up one small win after another--and realizing that followers are watching their every move. A host of renowned bosses talk about the importance of thanking people, about the power of this small gesture and how failure to express appreciation to people who are working their tails off is a sign of disrespect. The late Robert Townsend, former CEO of Avis and author of Up the Organization, defined "Thanks" as "A really neglected form of compensation." Max DePree, former CEO of furniture giant Herman Miller, described saying "thank you" as among a leader's primary jobs.
I thought all this talk about something so small and so obvious was overblown until a professor from another school told me about a trip he took with his university president to China. The logistics of the trip were difficult, as it was a traveling road show where transportation, hotel accommodations, meetings, and hundreds of other little details, had to be orchestrated. The staff traveling with the group worked 12 to 16 hours day on these chores and did a magnificent job. Yet my colleague reported that, even though the president made many requests of the staff during the trip, he never once thanked them. This lack of gratitude was demoralizing, as they catered to his every whim but weren't otherwise noticed or appreciated.
This perspective on the power of simple expressions of appreciation is bolstered by a series of four intertwined studies by Adam Grant and Francesca Gino in a paper called "A Little Thanks Goes A long Way: Explaining Why Gratitude Expressions Motivate Prosocial Behavior." These researchers found, in each study (all are randomized experiments with control and treatment conditions), that a simple expression of thanks by someone in authority led people to be more likely to volunteer to do extra work. Their research shows that this happens because the simple act of being thanked makes be feel more valued--and in some of these studies--it also increased peoples' feelings of self-efficacy (essentially, the perception that they were making a bigger impact on the world around them).
I was especially interested in the study with university fund raisers. The simple act of having a boss come by and offer a public thanks to one group, and but not the other, really packed a wallop. These fundraisers were paid a fixed salary, so Grant and Gino compared the number of phone calls made be each fundraiser before and after the "thank you" intervention. The results were pretty impressive, as while there was no change in the average number of calls made by the group that was not offered thanks, the folks who heard a warm two sentence thank you from a boss made an average of about 50% more calls during the subsequent week.
To return to the argument in Good Boss, Bad Boss, it appears we have some new evidence, as Robert Townsend put it, that "Thanks" is "A really neglected form of compensation." It is also a remarkably cheap form of compensation.
Reprinted from Work Matters 
Robert I. Sutton, PhD is Professor of Management Science and Engineering at Stanford. His most recent book is The New York Times bestseller The No Asshole Rule: Building a Civilized Workplace and Surviving One That Isn't . His next book, Good Boss, Bad Boss: How to Be the Best...and Survive the Worst , will be published September 2010. Follow him at twitter.com/work_matters .