"DADT" Linked to Poor Performance

"There doesn't even have to be a serious, formal conversation," said Melissa Ferguson, a psychology professor at Cornell and the study's second author.

In explaining the study's findings, the authors suggested thinking of the mind as a battery. Concealing one's sexual orientation requires monitoring one's actions and social environment, tasks that draw on limited mental resources. After the conversation, participants' "batteries" are lower, causing them to perform worse on an array of tasks.

After a while the effect disappears, though researchers have not determined how long it lasts.

The fact that physical endurance is affected might seem strange, but Critcher explained that physical tasks are mental too.

"After a period of exercise, your body is telling you to stop and you override this," he said.

Critcher and Ferguson stressed that this effect is not about "mental anguish" caused by concealing one's sexual orientation. Even participants who reported they were not fatigued or upset by the conversation still demonstrated the effect.

"It's nothing about participants reporting distress," Ferguson said. "It's about their actual competence."

The study also suggests that the experience of hiding one's sexual identity did not significantly improve performance, though more research needs to be done. Previous work has shown that gays and lesbians who work under "don't ask, don't tell" may fail to receive adequate medical or psychological care for fear of revealing their sexual orientation, but this study is the first to draw a direct link between the policy and performance on tasks that are relevant to military service.