Turns out, it also can help make you more persuasive, too.
If you’re a manager and you’re the recipient of a colleague’s generosity, you can increase the likelihood that the person will do it again in the future if you express your appreciation, according to Adam Grant, a psychologist and professor of management at the University of Pennsylvania’s Wharton School.
Psychologists have done extensive research into how people feel after they have received favors, gifts, or other forms of kindness, but there is little research into how people who perform acts of kindness are affected by an expression of gratitude.
So Grant conducted four experiments and wrote in the Journal of Personality and Social Psychology that the “thank you” positively affected the self-image of those who performed the kind gestures.
In two experiments, people who received a written thank-you note were motivated to help that same person again, as well as another person. In a third experiment, after a supervisor had expressed gratitude to a group of fundraisers in a call center, the callers spent significantly more time on the phone. And in a fourth experiment, people who received a thank-you felt socially valued.
Increasing the sense of self-worth is where gratitude has its greatest impact, Grant said, because people form a self-view according to their feeling of competence and their sense of community—their feeling of connectedness to people around them.
Psychologists have found that the sense of being valued by others is a fundamental human motivation. People who need help sometimes refuse it because getting help will make them feel needy and incompetent. Consequently, people who want to lend a hand will often withhold the help, thinking that their gesture won’t be valued. But if the person who needs assistance says he is grateful for the help, that reduces the helper’s uncertainty about whether his kindness is of value and is appreciated.
"Expressions of gratitude signify that a beneficiary values, needs, appreciates, and accepts one's assistance, rather than rejecting or devaluing it," Grant said.
Making a habit of saying thank you in the workplace can make you more persuasive by strengthening your credibility. Saying thanks is an admired character trait, and it makes you more likeable. And people are persuaded to do things for those they like.