Is your Roomba a boy or a girl?

The Roomba, of course, is that clever little house-cleaning robot. I reviewed Roomba in October 2002, then bought my own a few months later. Since then it’s been happily sweeping my living room and dining room every week or so. It also terrifies my cats and my three-year-old twin boys. All well and good—but what’s the Roomba’s gender?

“It’s a girl,” says my wife. “It’s round. It’s close to the floor. It ends with an ‘a’. I always think of it as a ‘wom-ba.’”

But if the Roomba is a girl, then Asimo is definitely a boy. Developed by Honda Motor, Asimo is a humanoid robot that walks around like a short astronaut in a white space suit. Four-foot tall Asimo is the latest in a long line of the company’s bipedal robots. These days Asimo spends his time as Honda’s goodwill ambassador to the world’s science museums, auto shows, and other venues. Last month he was spotted in Hanoi, Vietnam.

Asimo doesn’t look especially boy-like—there’s no slingshot in his back pocket, there’s no telltale bulge under his belt, and there’s no hint of facial hair. In fact, you can’t even see his face: the robot’s head is covered with a visor that has just two big holes for its video-camera eyes. But Honda repeatedly refers to the robot with the pronoun “he” on the Asimo website.

Indeed, Honda has taken great pains to make its walking robots more lifelike, and part of that realism appears to include giving the robot a friendly sounding name (the previous generation was called simply “P3”). The company’s earliest attempts at walkers were really nothing more than a pair of legs and feet with a big box on top of them. But over the years the robot forms have become decidedly more human—and more male.

Whether or not you think that gender belongs in our mechanical creations has a lot to do with your vision of how these creatures will fit into our future. It certainly takes more effort to make a robot that’s gendered than one that’s asexual. But engineers just want to have fun. Building gender into robots might be a way for the robots’ designers to express their own playfulness and creativity.

Dig a little deeper, though, and you’ll discover another reason why gender might be a good thing for our robot servants: gender will make robots more compatible with their human masters.

As human beings, we constantly try to layer emotions, desires, and other human qualities onto our machines. Computers aren’t aware of the emotional traits that we assign to them, of course. We might say “the computer ate my file because it’s having a bad day” because we lack a better explanation for what’s happening inside the system’s microprocessor (its “brain.”) Yes, there have been attempts to develop synthetic emotions for machines, but that’s all artifice. Most people realize that fundamentally there’s nothing going on inside the silicon except the cold calculation of ones and zeros.

Still, if you are interested in building an effective interface between humans and computers, you might just be better off creating a machine that projects a simulated emotional response. Because human beings are hard-wired for emotions, we might find it easier to work with such machines—especially if these machines were sharing our physical surroundings, rather than being good little drones on the factory floor or up on Mars.

Such thinking is behind a growing movement in robotics to build machines that portray emotions. Cynthia Breazeal was a big proponent of this idea when she was a graduate student at the MIT Artificial Intelligence Lab. Her doctoral project “Kismet” was a disembodied robot head with incredibly expressive eyebrows, ears, and mouth. The robot could look happy, afraid, engaged, bored, sleepy, or even confused. Kids loved Kismet. Now a professor at the MIT Media Lab, Breazeal and her students are working on Leonardo, an elaborate robot with more than 70 motors in its ears, eyes, face, neck, and arms—more emotional expressiveness than any robot or puppet that has ever been built. Leonardo can literally shrug its shoulders with apathy or disapprovingly shake its head back and forth—or even curl its ears like Yoda. Other researchers around the world are engaged in similar projects.Can you have sociability without gender? Kismet feels like a girl, even on videotape. Leonardo is definitely a boy—even before you know his name.

For as long as inventors have been building robots, they have been imbuing their creations with gender. Legend has it that René Descartes built a female mechanical doll modeled to substitute for his daughter, who died in 1640 at the age of five. A hundred years later, the French engineer Jacques Vaucanson built a mechanical woman who could play the flute. Baron Wolfgang von Kempelen built a machine called “The Turk,” which appeared to play chess. (Alas, The Turk’s brain was actually a midget that was hidden inside the automaton, making the machine either a cyborg or an elaborate rouse, depending on how charitable you want to be. Nevertheless, von Kempelen still made a decision to give The Turk human form—and a male one, at that.) When Mary Shelly wrote her novel Frankenstein, it must have seemed only natural to her that the good doctor’s 8-foot-tall monster would be male. In fact, the monster’s only wish was for Dr. Frankenstein to build it (him?) a female companion.

Last year, Neiman Marcus made the headlines by featuring a pair of "his & her" domestic robots in its Christmas catalog. Priced at $400,000, the machines were the handiwork of a small New York firm, International Robotics. You can’t find the robots on the Neiman Marcus website, but an article at the Onrobo.com website says that "his" robot (presumably the female) “is designed to respond empathetically to humans” while "her" robot “will help you carry in the groceries from the car or leave a message for your spouse.” (More coverage can be found at the AsiaOne website.)

Why bring gender roles into the cybernetic age? “Because it is an essential part of how human beings can choose to be entertained and amused by the machines they will co-habit with,” says Robert Doornick, International Robotics’ president and CEO. Long term, says Doornick, “the issue of gender is more or less a choice that has to be made by the people that these robots will cohabit with.”

Back at the Media Lab, graduate student Cory Kidd doesn’t deny that gender permeates the robots that he’s creating. “It’s not something we’ve given a lot of thought to building in.” But, says Kidd, “you can’t avoid it.” Just think about the classic robot of Star Wars, R2D2. “Most people would agree that it’s a boy,” says Kidd. “But I can’t think of anything that makes R2D2 gendered.” Perhaps, speculates Kidd, we think that R2D2 is a boy “because he hangs out with the guys.”

Or maybe it’s all the whistles and that short stubby body.