Shuffle Speller is a typing interface that can be used with brain-computer interface or with other alternative access methods, such as eye tracking. For some users with severe speech and physical impairments, alternative access methods such as eye-gaze, head-pointing, or switch access may be inaccurate or unreliable, which can make typing difficult. In many typing interfaces, an error on a single selection will result in the wrong character being typed. Shuffle Speller is designed to compensate for an unreliable access method by asking for more user input, when necessary.

How it works

Shuffle Speller divides letters up among several boxes on a computer screen. To select the letter E, the user first selects the box containing the E, along with a few other letters. Since Shuffle Speller cannot be sure whether the user wants the E or one of the other letters, it "shuffles" the letters around the screen into different boxes. If the user selects the E again, this time by itself or with a different group of letters, then the computer may have enough evidence to know that the user wanted the E.

In our experiments, participants access Shuffle Speller with either brain-computer interface or eye tracking. In Brain-Computer Interface mode, flashing lights are placed next to each box on the screen. The lights all flash at different rates. When the user looks at one of the lights, her brain produces a response that is in time with the flashing rate of that particular light (similar to clapping along to the beat of a song). The user wears an electrode headband, which picks up that response and allows the computer to guess which box she wants. In Eye-Tracking mode, a special camera at the bottom of the computer screen tracks the user's eye movements, so she can look at a box to make a selection.

During a calibration session, Shuffle Speller identifies patterns in the user's brain responses or eye movements, including errors and inconsistencies. This helps it customize to individual users and improve typing accuracy.

Below, is a screenshot of the user interface of Shuffle Speller.

How we tested it

Although eye tracking with traditional communication software is often used by people with severe speech and physical impairments, it does not work for everyone. We recruited individuals with severe speech and physical impairments who have difficulty using traditional eye-gaze communication software due to impairments in vision, eye movement, or other function. These participants used Shuffle Speller with both eye-tracking and brain-computer interface. We tracked typing performance and user experience feedback.

How to learn more

To learn more about our current brain-computer interface experiments, please contact:

Betts Peters, Ph.D., CCC-SLP