Why Facebook's version of Siri isn't a man or a woman

When Siri launched in the U.S., the virtual assistant technology had the voice of a woman. In the U.K., Siri was a male.

Microsoft's Cortana virtual assistant originally launched as a female, but an update to Windows 10 allows people to change Cortana to a male's voice.

But Facebook's new M assistant is designed to be neutral and gender-less.

"We wanted M to be abstract," said Alexandre Lebrun, founder of Wit.Ai, which was acquired by Facebook in January. "There is not a real name. It's just M, not even a full name."

Facebook's M, which is still in testing and available to a very small number of users, doesn't even have an avatar so that it can remain professional and neutral, Lebrun explained.

That can be tricky, considering M still has humans "trainers" involved in every single question and task it gets from users, which can range from calling Comcast about a cable bill to sending flowers to a loved one. In comparison, Siri and Cortana don't have humans looking at every question. Siri's creator, Adam Cheyer, said they chose to create Siri with more of a personality. Her (or his, depending on how you've set it) responses can be witty.

Facebook wants M to be neutral and personality-less as it develops.

"Even when trainers are involved, we don't want you to feel like you talked to Anna and then you talked to Joe. We wanted it to be consistent across your experiences, which is hard to do," Lebrun said.

To manage it, M takes a look at the question first and suggests answers. A human trainer then picks the best one to send to the Facebook user, rather than writing it up themself. It's hard, Lebrun admits, "but it's doable."