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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