It sounds like science fiction, but it seems japanese researchers have managed to extract letters using a functional magnetic resonance imaging (fMRI) machine!
Via Pink Tentacle:
"The scientists were able to reconstruct various images viewed by a person by analyzing changes in their cerebral blood flow. Using a functional magnetic resonance imaging (fMRI) machine, the researchers first mapped the blood flow changes that occurred in the cerebral visual cortex as subjects viewed various images held in front of their eyes. Subjects were shown 400 random 10 x 10 pixel black-and-white images for a period of 12 seconds each. While the fMRI machine monitored the changes in brain activity, a computer crunched the data and learned to associate the various changes in brain activity with the different image designs.
Then, when the test subjects were shown a completely new set of images, such as the letters N-E-U-R-O-N, the system was able to reconstruct and display what the test subjects were viewing based solely on their brain activity.
For now, the system is only able to reproduce simple black-and-white images. But Dr. Kang Cheng, a researcher from the RIKEN Brain Science Institute, suggests that improving the measurement accuracy will make it possible to reproduce images in color.
“These results are a breakthrough in terms of understanding brain activity,” says Dr. Cheng. “In as little as 10 years, advances in this field of research may make it possible to read a person’s thoughts with some degree of accuracy.”"
This opens up some insane possibilites if you ask me!