There are many reasons to hate open offices: They’re loud , prone to thieves , and, most of all, lack any kind of privacy . But a new research paper reveals yet another knock against them: They’re subtly sexist.

Researchers Alison Hirst of Anglia Ruskin University and Christina Schwabenland of the University of Bedfordshire studied the process of a local government moving its 1,100 employees from a series of traditional offices to one big open office over the course of three years in the U.K. The new office had all the markings of a typical open plan office–glass everywhere, identical desks for everyone, and collaborative group spaces–and was designed with the intention of breaking down hierarchies and encouraging employees to engage with each other more. As the researchers wrote in their paper, which was published in published in Gender, Work and Organization, “it was designed to enchant rather than control overtly, and to encourage movement rather than fixity.”

To understand how people adjusted to the new office, Hirst interviewed 27 women and 13 men for one to two hours over the course of three years, with two intensive periods of observation and interviews and many other visits. Besides interviews, Hirst also participated in some of the office’s culture, having lunch and informal coffee breaks with employees and attending meetings. While some female employees felt like the new office space promoted equality, others had the opposite reaction. The researchers found that many women became hyper-aware of being constantly watched and their appearance constantly evaluated; multiple women told them that “there isn’t anywhere that you don’t feel watched.” Of the men Hirst interviewed, there was no evidence they felt similarly or changed their actions as a result of the lack of privacy.

The architect of the new office, who was kept anonymous, anticipated that people might feel uncomfortable with the heavily glass office at first, but in interviews with the researchers, he said he thought people would get used to it. “I think it’s like going to a nudist beach. You know, first you’re a little bit worried that everyone’s looking at you, but then you think, hang on, everybody else is naked, no one’s looking at each other,” he told the researchers. “I think that’s what’ll happen, they’ll get on with it.”

The only problem is that sociological research of nudist beaches has shown that people do continue to watch each other–“men in particular, often in groups, look obsessively at women,” the researchers write. This kind of all-glass, no-privacy environment leads to a subtle kind of sexism, where women are always being watched and thus judged on their appearances, causing anxiety for many employees. One woman named Pat told the researchers that the men on her team used to “mark” the attractiveness of young women coming into the office for interviews. “Visibility enabled these men to judge and rank women according to their sexual attractiveness, just like men on the nudist beaches,” the researchers write.

Some women would avoid visiting parts of the office where they weren’t expected: “You just don’t, do you? Right, this is going to sound extremely sexist but remember I do work with a lot of men,” a woman named Wendy told the researchers. “If you were a female, that would definitely get a comment from all the men because they would notice you.” For Wendy, the design of the office, despite the architects’ intention of promoting freedom of movement, actually inhibited it.

Conscious of male eyes, some women began to dress differently. Without an architectural layout that indicated their place in the office hierarchy, they began to rely on their clothing to signal to other people whether they were important or not. One woman told the researchers that she started wearing jackets and stopped wearing cardigans because the latter would indicate that she was in admin. Others began to wear more makeup or dress up more, conscious that people were looking at them all the time.