The Mental Typewriter

Scientists demonstrated a brain-computer interface that translates brain signals into computer control signals this week at CeBIT in Berlin. The initial project demonstrates how a paralysed patient could communicate by using a mental typewriter alone – without touching the keyboard. In the case of serious accident or illness, a patient’s limbs can be paralyzed, severely restricting communication with the outside world. The interface is already showing how it can help these patients to write texts and thus communicate with their environment. There’s also a PONG game (computer tennis) used to demonstrate how the interface can be used. Brain Pong involves two BBCI users playing a game of teletennis in which the “rackets” are controlled by imagining movements and predictably the general media has focussed the majority of its attention on computer gaming applications but BCCI could equally be used in safety technologies (e.g. in automobiles for monitoring cognitive driver stress), in controlling prostheses, wheelchairs, instruments and even machinery.

On the first day of the 2006 CeBIT Computer Fair, Fraunhofer FIRST and the Berlin Charité demonstrated how the mental typewriter could be used for this purpose. On the other days of the CeBIT Fair, a simulated test setup using a shop-window dummy will be on display.

Cooperation between Fraunhofer FIRST and the Charité to develop an interface between the human brain and the computer began some years ago. The result was the Berlin Brain-Computer Interface (BBCI which uses the electrical activity of the brain in the form of an electroencephalogram (EEG). Electrodes attached to the scalp measure the brain’s electrical signals. These are then amplified and transmitted to the computer, which converts them into technical control signals. The principle behind the BBCI is that the activity of the brain already reflects the purely mental conception of a particular behaviour, e.g. the idea of moving a hand or foot.

The BBCI recognizes the corresponding changes in brain activity and uses them, say, to choose between two alternatives: one involves imagining that the left hand is moved, the other that the right hand is moved. This enables a cursor, for example, to be moved to the left or right. The person operating the mental typewriter uses the cursor to select a letters field. The next step reduces the choice, and after a few more steps we arrive at the individual letters, which can be used to write words. This process enables simple sentences to be constructed within minutes. A first prototype of the mental typewriter is currently available. In a series of experiments, different spelling methods are tested in terms of their usability and are adapted to the BBCI. It will be some years, though, before the mental typewriter can be used in everyday applications. Further research is needed, in particular to refine the EEG sensors.

The two project heads, Prof. Dr. Klaus-Robert Müller (Fraunhofer FIRST) and Prof. Dr. Gabriel Curio (Charité), will be available for interviews.