Change Blindness, Saccadic Masking: Eye Hacks – Oh My!

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In the above video, 75% of the people tested failed to notice that the person they were talking to was swapped with a different person during their conversation. In a similar experiment conducted by Derren Brown, about 50% of people failed to notice that a person asking them for directions was

swapped-out during their interaction. This phenomenon is referred to as Change Blindess or Inattentional Blindness – our inability to detect large changes in a scene.

We also experience some form of ‘blindness’ on a very small scale. Our brain performs something called Saccadic Masking during certain types of fast eye movements (saccades), where our vision is massively impaired during the movement, but our brain uses before and after snapshots to hide the fact that we were unable to clearly see during the movement – in effect, it is hiding the useless blurred image of movement from us.

You can see this in action with a simple experiment. Grab a friend and a mirror. Look into the mirror, and stare at one eye, then switch to the other, then back again. You won’t be able to see your eye movement (your brain is masking it), but your friend will.

For more information, check out Hack #17, Glimpse the Gaps in Your Vision (pdf) from O’Reilly’s excellent Mind Hacks book.

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Numbers Stations – The Soundtrack to Your Nightmares

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Listen to a minute of this, from about 0:50 onwards: The Swedish Rhapsody (MP3).

This spooky sound is sampled from a Numbers Station. Hundreds of these shortwave radio stations exist around the world, transmitting numbers, letters, beeps and simple tunes. Their origin – and ongoing transmissions – still largely remain a mystery.

Are they secret codes and directives for spies in foreign countries? Are they sources of misinformation to distract the enemy? Perhaps messages between druglords? Hoaxes by amateur enthusiasts? The answer is probably: yes, all of these, and more besides.

The Conet Project sampled 150 transmissions from 20 years and released them on a 4CD set (“Not available in stores!“, I suspect). This is currently “out of stock”, but the recordings are also available on archive.org, should you wish to disturb yourself some

more.

You can read more about Numbers Stations on Damn Interesting, and Boing Boing’s coverage of the copyright fight between The Conet Project and Wilco, who used a sample of the recordings on their Yankee Hotel Foxtrot album. Wikipedia also has entries for some individual stations, including The Lincolnshire Poacher, Cherry Ripe, and UVB-76.

Lego spy photo under Creative Commons license from Flickr user Dunechaser.