    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.

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