Have you had this experience: You observe a star team member performing well with the rest of your team but notice they perform differently, or even clam up, when you interact with them? Could it be your management style? Maybe. But for those of us having a few years experience under our belt managing people we typically adjust our interactions based on the individual. It's when this fails we are left to wonder about possible causes of inconsistent employee performance.
Here's an interesting angle on the issue I came across while listening to NPR. In "How Stereotypes Can Drive Women To Quit Science" the story brings to light something called "stereotype threat," explaining that "when there's a stereotype in the air and people are worried they might
confirm the stereotype by performing poorly, their fears can
inadvertently make the stereotype become self-fulfilling."
So, if you rule out management style, it could be a psychological phenomenon on the part of your team member. You may want to keep "stereotype threat" in the back of your mind as a possible cause for inconsistent performance and think of a charitible way to approach the situation. Perhaps asking your team member what you can do to help them perform better might be a good place to start in quashing any insecurities or misconceptions they may have about you or themselves.