I used to love the idea of disguising a girl as a boy. Then I saw an episode of Cadfael that made me wonder if it would ever work. In “One Corpse Too Many” (S1:E1), I recognized a robed figure as a female just from the way she walked. While the body was completely covered and the hood was up, I knew the figure for a girl. And it was a girl disguised as a boy, supposedly fooling everyone around her, except of course for Cadfael.

The girl disguised as a boy trope is common enough, especially in romance, fantasy, and historical literature. There are plenty of books and movies that use this device. Even Shakespeare includes women in disguise in several of his plays. The image of the supposed boy pulling off her cap to let her hair fall around her shoulders to the surprise of whomever she is talking to has become a movie cliche. Could this work in real life?

A good friend, when told by her brother that he intended to have his heroine wear pants to disguise her sex, said quite wisely, “I wear jeans all the time and no one has ever mistaken me for a boy.” At the same time, my sister, who used to have a buzz cut, often got mistaken for a male, especially by older people. As soon as she spoke to the person, they saw their mistake, but their initial “read” of her, as a thin, short-haired person, was of a boy.

Apparently, the expectations of the audience plays an important part in the success of such a deception. There’s even a psychological phenomenon that might help with this: motivated perception. Studies show that what people believe they see is affected by their expectations. In other words, they will see what they want to see if it matters enough. For people with strong assumptions about gender and dress and a desire for things around them to fit the norm, they might see a boy when confronted with a girl dressed like one.

If this is the case, how did I know the figure in the hood was a girl? Seeing a monk’s habit, I should have expected a boy. But we live in a time when the lines between genders are blurred and the cues that used to be clear cut have evaporated.

I realized this the other day, when my 8-year-old nephew has asked us how to tell boys from girls. All the signs I used at his age no longer work. He knows boys with long hair and girls with short hair. Names like Skyler belong to boys and girls. Girls wear superhero t-shirts and boys wear pink. In the end, there’s only one way to get it right: ask.

I’ve heard it argued that the reason Shakespeare got away with his disguised girls was because all the actors on the Elizabethan stage were male. A boy playing a girl dressed as a boy could easily pull off the role. But having thought about it more and weighed the evidence, I think his audience’s assumptions were important, too. They relied on dress as a cue to gender, and used it automatically, making a girl disguised as a boy a plausible trick.

What do you think? Can a girl dressed as a boy fool viewers? Or is this trope rarely feasible? Do you love it or hate it?