I know little about this area and current commercial options seem limited to novelty products for 'brain training' and slow/simple gaming, or very slow text entry of only a few WPM aimed at people suffering from total paralysis. I'm having trouble sifting practical information all the marketing and gee-whiz hype in this emerging field.
I'm being vague on the medical issues both for privacy and to avoid side discussions about diagnosis, prognosis, or treatment, which are already well in hand. So all I will say is that it's not a neurological issue. Thanks for reading.
I had to dig a bit to find it, I remember hearing about it long, long ago... it's a cool idea. It creates a continuously expanding set of next letters to the already typed text on the right, with the size determined by probability. The more to the right you move, the faster it goes... if you make a mistake, just move to the left.