How can a flashing grid let someone spell without reading a letter from the brain? · Lobeworks/17

The interface never looks for the letter in the brain.

How can a flashing grid let someone spell without reading a letter from the brain?

The interface never looks for the letter in the brain. It flashes the rows and columns of a grid while the person attends to the letter they want, and only the flashes that light that letter carry a P300, the brain's response to an event that matters. The row and the column that evoked it meet at the letter. The design moves the hard part from decoding to the screen: an intention that no recording could read directly becomes a choice among options the interface offers, each answered with a response that is easy to tell apart.