Paula Davis, founder and CEO of The Stress and Resilience Institute.

Bosses can make all kinds of gestures to show employees that they care: from offering raises and in-office childcare to providing free gym memberships or branded merchandise, like hoodies and water bottles.

But a show of appreciation doesn't have to be big, expensive or extravagant to have a meaningful effect, says leadership consultant and resilience expert Paula Davis. There are small things bosses can do to make the workplace feel comfortable and inviting, which can lead to higher productivity and lower turnover rates, research shows.

Davis calls these actions "tiny noticeable things," or "TNTs." A highly underrated TNT that too many bosses overlook is what Davis dubs a "thank you, plus."

"A lot of leaders struggle with recognition, and they struggle to just remember to say 'thank you,'" says Davis, founder and CEO of the Stress and Resilience Institute, a workplace training and consulting firm. "The 'plus' piece is to add the specific behavior or strengths that you saw that led to the good outcome."