Wendy Wang, like many mezzo-sopranos, hopes one day to sing the role of Carmen, the title character in the famous opera by Georges Bizet. But there's an autobiographical impulse to her ambition.

"I'm sure one day when I'm singing Carmen, I can relive my freshman summer," she says.

She's referring to Act 1, in which Carmen is hand-rolling cigarettes in a tobacco factory. During her freshman summer (2008), Wang too worked with her hands. She was an embedded employee on the lines of the world's second-largest mobile phone factory, located in southern China.

"The hardest part was standing for 10-plus hours a day. There were no chairs on the factory floors. We were on our feet the whole time," she says.

The embeds, all of whom were Chinese-born Harvard undergrads, worked, ate, and lived alongside their co-workers, who were not privy to the embedding. The students were part of an experiment led by Ethan Bernstein, an assistant professor of business administration at Harvard Business School.

Bernstein's aim, boiled down, was to research a thorny paradox of workplace transparency: How well can you do your job if you're being constantly monitored? While transparency initiatives can stem from benevolent ideals, they often end up hindering productivity.

After all, it's hard to be your smoothest or smartest self on the factory floor when you know you're being actively watched (and possibly evaluated) at every moment.

"Unrehearsed, experimental behaviors sometimes cease altogether," writes Bernstein in a Harvard Business Review article summarizing his experiment's findings. "Wide-open workspaces and copious real-time data on how individuals spend their time can leave employees feeling exposed and vulnerable."

The work of Wang and the other embeds helped Bernstein research his HBR article, which is called "The Transparency Trap." Bernstein's findings first appeared as a longer article in Administrative Science Quarterly. Both articles detail how workers conducted their tasks when they were observed, versus when they were unobserved.

Even seemingly unremarkable behavior--such as wearing rubber gloves when assembling or handling components--changed immensely. Factory rules stated that line workers were supposed to wear gloves or fingertip covers on both hands. But here's what one of the embeds noticed, when the workers were unobserved:

People usually wear their gloves in their own ways--either they wear a glove on only one hand or they cut their gloves so their fingertips stick out, giving them a bare hand or bare fingertips so when they are doing little things it goes a lot faster.

You can see how fruitful this observation is. On the macro level, it reveals employees obey glove procedures only when they're watched. On more granular levels, it suggests that the gloves are poorly designed; that employees will break rules (and endure safety risks) to meet productivity goals; and that management has possibly overstressed productivity at the expense of safety.

For Wang and the other embeds, the initial challenge was blending in as factory workers. Once they were established as line workers, they could stealthily observe employee behaviors. During their allotted 40-minute breaks, which occurred once every four hours, the embeds relayed their observations to Bernstein, who waited in an isolated office on a separate floor.

Specifically, the embeds verbalized what they'd noticed into a voice recorder, which Bernstein then transcribed. At the end of each day, the embeds returned to the office to record any leftover observations and review the day's findings as a team. It was a classic case of ethnographic observing, recording, and sharing.

While Bernstein screened all of the embeds for their ability to blend, the embeds were still nervous about getting discovered. "I was a little scared," says Jieliang Hao, who grew up in China and came to the U.S. when she was 11 years old. Her stint as an embed was her first trip back to China.

"[The factory workers] were a different social class than I was used to seeing," she said. "My parents are both academics, and I wasn't accustomed to that world."

Spoken language was not an issue for Hao, but "I knew if they made me write something, you could tell my handwriting is that of a sixth grader," she adds.

Xiao Cong was nervous for a different reason. She originally hailed from the northern part of China. By contrast, most of the factory workers were from the southern countryside. Cong was worried her northern accent would arouse suspicions. "I'm also fairly tall," says Cong, who, at 5-foot-8, is "taller than most guys in the southern part of China."

Despite these mild anxieties, and despite their towering heights (Wang, for her part, is 5-foot-9; Nathanael Ren, another embed, is 6-foot even), the embeds blended right in. So the real work--the factory duties of standing for more than 10 hours a day on an assembly line--began.

The embeds' day-to-day tasks ranged from installing tiny rubber buttons with tweezers to consulting with upper management on best practices. Cong clipped the front and back halves of the phone together, while Hao worked with the boards inside the phones. Initially, these boards rolled down the conveyer belt as four boards stuck together.

"Then they'd get cut into individual ones that each go into a cell phone," she said. It was two in the front of the phone and two in the back.

"Sometimes I'd forget the back," Hao says. Of course, it wasn't that she truly forgot. It was that carelessness and pressure took hold at some point during 10-hour shifts beside a nonstop conveyer belt. Later, she worked on box assembly, making sure all of the phone's accessories squeezed in just so. Another of the embeds, Steve Lin, used an electric screw driver dangling from the ceiling to screw the phone covers together, after the data cards had been inserted.

Ren worked as an adviser embedded into the engineering unit, providing Bernstein with a different perspective on the factory's practices. What most stands out in his memory is the way "managers didn't think as much at a macro level as I thought they would," he says. He recalls how management initially "ignored" his well-reasoned arguments to raise worker pay.

"It was the way they dismissed the feedback, when it was such a fundamental consideration," he says.

For Ren, it was chiefly a lesson in the unintended consequences of hierarchical structures. The idea of getting through the day, doing what you're told, and not rocking the boat existed not only on the floor of the factory--where workers concealed their gloveless efficiencies from managers--but also at higher levels, where those selfsame managers, too, seemed reticent to adopt the most reasonable change initiatives.

Today, Ren is living and working in the Boston area, part of a six-person startup in the health care tech sector, scheduled to launch next summer.

Hao is also employed at a startup. She's working in Silicon Valley, on a project so stealthy that all she'll reveal is the single word "hardware." Her main takeaway from her experience in China was the discovery that--strenuous as the factory work was--she really liked using her hands.

Hence her affinity for hardware, especially after working on Wall Street for two years after graduation. "I like things I can see and touch," she says. "Finance was so abstract and so far from life. I knew I wanted to do something that makes a difference on a very human level. I wanted to be able to answer the question, What can your product do?"

Then there's Wang, who's earned her master's in opera at the Conservatory of Vienna. She's sending out recordings of her performances and reference letters, hoping to land roles. One girl whom Wang befriended at the factory had the goal of wanting to become a translator one day. "Every day on the factory floor she bought her flash cards with English vocabulary words," Wang recalls. "And whenever she had a second to spare, she would memorize them as she did these tedious tasks.

"That kind of drive--her determination--it reminds me that especially with opera, the odds of succeeding are so slim. But it's about the daily efforts. That makes a difference. Keeping up the hope despite the circumstances."