If someone secretly controlled what you say, would anyone notice?

But in recent years, several performance artists have revived the concept. “I thought it would be fun to test this idea of cyranoids in the wild,” said Robb Mitchell, an artist and professor of social interaction design at the University of Southern Denmark. In 2007, Mitchell organized an exhibit at an art gallery in Dundee, Scotland. He wore a silly hat adorned with a camera and other gadgets as he wandered through the gallery talking to visitors. “We tried to make it really obvious and not too scary for people,” he said. Mitchell wore a radio receiver in his ear, and visitors could take turns controlling his speech from a nearby room.

Even people who knew him didn’t catch on, despite the fact that he acted like he’d never met them and offered odd responses to their questions. “That was a huge surprise,” Mitchell said. “They couldn’t get past the idea they were talking to me.”

In an even more bizarre exhibit, artists posted flyers around South Bank in London proclaiming that a unicorn would appear at a certain time. Nobody actually thought a unicorn was going to appear, but people gathered around anyway to see what was up, says Gillespie, who helped organize the performance.