Make People Mute By Forcing Them To Listen to Themselves

You can't talk and listen at the same time. Scientists proved this conclusively when they came up with speech shadowing experiments that rendered people mute by forcing them to listen to the drivel coming out of their mouths.

In the 1950s Ludmilla Andreevna Chistovich, a psychologist in the USSR, had probably had just about enough of listening to tedious propaganda. She was hardly alone, on either side of the Iron Curtain, but she decided to do something about it - something really poetic. Chistovich invented a technique called "speech shadowing," or "speech jamming."

The shadowing technique involved nothing more than asking people to speak into a microphone while wearing headphones. Chistovich broadcast their own words back to them, with about a 250 millisecond delay. For the most part, this rendered them speechless. In the first round of experiments, only about 25 percent of women, and no men, could keep talking while listening to themselves. Give them a 500 millisecond delay and they were okay, but that slight delay - roughly the delay of one syllable - shut them up. After subsequent experiments, Chistovich determined that the slight delay forced people to process their own speech, making them listen to it as if it were being said by someone else. This proved too great a distraction for them.

What about the people who could speak? These people, dubbed "close shadowers," also seemed to process the speech they were hearing, but managed to barrel ahead anyway by setting their mouth on autopilot to read whatever was in front of them. Their attention was divided, though. Further strains on their attention forced changes to their technique and threw them off.

Attempts to bring down the close shadowers have taken many forms over the years. One of the latest experiments involves reading, speaking, and listening, while driving. (Fortunately for the public, the driving was done in a driving simulator and not on the road.) Scientists found that close shadowers could keep on the road and read and listen if the screen they were reading from was placed in front of them. Put it to the side, and they failed at at least one of their tasks.

I would love to see films of those simulations.

[Via Speech Shadowing and Speech Comprehension, Speech Shadowing While Driving.]