OVERVIEW
The Mind Switch refers to the technology that has been developed which allows a person to turn on and off an electrical appliance, such as a desk lamp or TV in 2-3 seconds using EEG signals, without training. Proportional control, such as turning up or down the volume of a radio is also possible with the technology. This research is being carried at the University of Technology, Sydney (UTS).

BACKGROUND - General
Early in 1994 while studying the response of the brain to environmental factors Professor Ashley Craig and Mr Paul McIsaac of the Department of Health Sciences at UTS, noticed an effect which appears to be common among all persons. That effect is an increase in a particular brain signal when a person closes his/her eyes for more than one second. The important question that Ashley and Paul then asked was could this effect be used to do something useful?, ie - could the control of the brain signal be used, in turn, to control something else? At this stage Ashley contacted Professor Tony Moon, the Dean of Science at UTS, to find out if anyone could help answer the technical questions and design a system that might exploit the apparent change in the signal level when a person closes his/her eyes. Professor Moon introduced Ashley to Assoc Prof Les Kirkup who is a associate professor in the department of Applied Physics at UTS, who has experience in developing electronics and instrumentation. It was thought he could offer important input to the project. He was initially sceptical that signals as small as those that are present on the scalp, (where electrodes are placed to pick up brain activity) could be detected reliably and analysed sufficiently quickly to allow activation of an external device, such as a lamp or TV. The data that had been gathered on signal levels with eyes open and eyes closed showed that a significant increase occurred in the 8-13Hz part of the 'brain spectrum' commonly referred to as the 'alpha' region. Les built a detection, discrimination and analysis system based on Ashley and Paul's data and, much to his surprise at least, the first person (Lucy) connected to the system showed the capability of operating a switch which could control an electrical appliance.

BACKGROUND - Technical
Serious work done on brain signals began with Berger in 1929 [Berger 1967]. Since that time the acquisition and analysis of brain signals, referred to as Electroencephalography (EEG) has advanced to such a state that EEG is regularly used to assist in the diagnosis of schizophrenia, epilepsy and brain tumours. [Geddes and Baker, 1989]. EEG has also been used in biofeedback studies in which subjects may learn to modify their EEG signals in response to visual representation of their EEG signals. This control usually take weeks or months to learn and is not highly reliable. The system we have developed does NOT rely on any learned skill by an individual. It simply requires a person to close his/her eyes for more than 1 second to effect sufficient change in the signals levels to allow for the reliable operation of a switch. It turns out that it has been known for many years that increase in signal level occur upon eye closure, but this is the first example (to our knowledge) of the recognition of its potential and the exploitation of the effect. The system used to detect the change in signals consists of amplifiers, filters and other signal processing elements (full details are still classified at the moment!). As there are other sources which can generate signals which can interfere with brain signals (and hence cause intermittent switching on and off of appliances) we have developed a noise suppression system which eliminates the effect of those noise sources. This feature is very important as we are currently developing the technology for disabled persons (we have a three year grant from the Motor Accident Authority of New South Wales, MAA) and reliability is a major issue. The funding from MAA has allowed us to appoint Mr Andrew Searle who has become a key figure in the technical developments regarding the Mind Switch. In addition Mr Perez Moses is developing new noise suppression techniques to be applied in this work.

Berger, H. 1967. On the electroencephalogram of man (trans. by P. Gloor).EEG Clin. Neurophysiol., Suppl. 28:1-350
Geddes, L. A. and Baker, L. E. 1989. Principles of applied biomedical instrumentation 3rd ed. (Wiley, New York): pp726-727

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