Russell Johnson of Michigan State University and his coresearchers asked managers to track the help they gave colleagues over 10 days and how recipients responded. The team found that when people lent a hand without being asked, they were less likely to be shown gratitude than when they helped upon request. Study participants also felt less sociable and engaged at work a day after they’d given proactive assistance. The conclusion: You shouldn’t volunteer to help your coworkers.

A version of this article appeared in the March–April 2019 issue (pp.30–31) of Harvard Business Review.