That peppy, cheerful person in your workplace—the one who always looks on the bright side and believes anything can be accomplished—isn’t necessarily a better performer than his more realistic, cynical or even pessimistic peers.

Nor is his work necessarily more reliable or better suited to company success.

So says a new study, from Eccles management professor Liz Tenney, that found that optimism doesn’t help a person’s performance as much as people might think.

The study—(Too) Optimistic About Optimism: The Belief That Optimism Improves Performance—was published in the March 2015 issue of the Journal of Personality and Social Psychology.

Read the full SHRM article here.