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Sending Messages With Your Brain Via EEG
An anonymous reader writes "From a University of Wisconsin-Madison announcement: 'In early April, Adam Wilson posted a status update on the social networking Web site Twitter — just by thinking about it. Just 23 characters long, his message, 'using EEG to send tweet,' demonstrates a natural, manageable way in which "locked-in" patients can couple brain-computer interface technologies with modern communication tools. A University of Wisconsin-Madison biomedical engineering doctoral student, Wilson is among a growing group of researchers worldwide who aim to perfect a communication system for users whose bodies do not work, but whose brains function normally.' A brief rundown of the system: Users focus on a monitor displaying a keyboard; the interface measures electrical impulses in the brain to print the chosen letters one by one. Wilson compares the learning curve to texting, calling it 'kind of a slow process at first.' But even practice doesn't bring it quite up to texting speed: 'I've seen people do up to eight characters per minute,' says Wilson. See video of the system in action."
...can be found here:
http://nitrolab.engr.wisc.edu/
Carousel is a lie!
Because the user might not be able to move his eyes.
The idea is that no focusing is required, just thought.
Now you're not only assuming that the user can move his eyes, but also blink at will.
The whole point is to bring communications to the very worst cases, who currently have no methods of communication because they can't control their body at all.
This system has been around for a while; I've seen it demonstrated live twice, and it didn't work at all either time. In my opinion, even in best conditions (bald patient, shit-tons of electrodes, professional setup, well-trained subject) it doesn't work well enough to fuel science-fiction fantasies, and probably never well. For locked-in patients, who can do nothing but move their eyes, though, it's an awesome technology. They made a movie recently about such a patient who spent years using it to write a novel: http://www.imdb.com/title/tt0401383/.
Here's how it works - metal electrodes on the brain (EEG) pick up an analog signal, and *any* stimulus which is particularly salient to a subject creates a spike in the signal 300ms after that stimulus appears (this spike is called the P300, there's a good wiki article on it). If you have a dude staring at a grid of letters, you can tell which one he's looking at by hunting for the big spikes 300 ms after the right letter flashes. The only problem is the signal-to-noise ratio, which is notoriously terrible in EEG, though of course there are people out there working on improving it.
Professor Hawking uses a more sophisticated system with word-prediction and a micro-switch activated by a slight motion of his shoulder. he can do much better than 8 cpm. I use a similar system but use eye gaze on a virtual keyboard rather than a sectoring keyboard.
Perhaps he's more accustomed to the sectoring keyboard or no longer has the ocular control for the eye gaze system.
I have something in common with Stephen Hawking...
What you're suggesting involves much more sophisticated signal processing methods involving narrow-band spectral detection. What this is is just a P300 speller, hooked up to twitter. What they're picking out using EEG is a broad event-related potential known as the P300 which is detectable by averaging traces together. You can find more about how it works here: http://www.gtec.at/products/g.BCIsys/P300_Speller.htm
And honestly, it's not that much better than an eye tracker. It just uses fancier technology.