E X P L O R E   T H E S E   L I F E   C H A L L E N G E S . . .

The Design Criteria of the Bilateral Psychogalvanometer (BPG)

By Keith Wakelam

The amplifier necessary for this type of Meter must be up to one hundred times as sensitive as the one used in a simple psychogalvanometer. This is because the changes in skin resistance that need to be detected are so much smaller. The focussing of attention in one hemisphere of the brain will cause a smaller change than an arousal of the whole brain and body. The relative differences between left and right sides of the brain in such cases may be less than one percent. The best analogy is that of a very delicate chemical balance, which will detect minute differences in mass. In addition, the double electrodes used can contact only a smaller area of the skin of each palm, so the basal resistances of the simple GSR Meter must be multiplied by a factor of three.

A switch is provided in the electrode sockets of the BPG Meter so that, if one electrode plug is withdrawn, an appropriate resistor will bridge it. This enables the BPG Meter to be used as an ordinary GSR Meter, to measure the overall resistance of the body. A separate scale is provided on the Meter for measurements in this mode. A measurement of the basal overall body resistance is necessary in order that conclusions can be reached regarding the likely responses of a subject. An appropriate development technique can then be selected for every individual.

For these purposes the amplification must be decreased so that readings do not go off scale. The BPG can then be used as a simple GSR Meter for preliminary exercises to bring the body resistance of the subject within the range necessary for bilateral readings.

The performance of the BPG Meter in the Bilateral Mode can be enhanced by the use of foot electrodes. Besides bringing a larger area of skin into contact with the electrodes, the hands are left free for the performance of tasks related to left and right brain stimulation .

To summarise, there are different states of arousal in each brain hemisphere in relation to specific tasks, which may be undertaken. Since the hands are connected to a large area of the Hippocampal Motor Gyrus in each opposed brain hemisphere, the electrical resistance of each hand will reflect the activity in that opposed hemisphere. This applies also to the soles of the feet. The differences of resistivity between each hemisphere can be displayed as a meter reading by a suitable instrument with a high gain amplifier.

The simple, Bilateral Psychogalvanometer will therefore perform a useful function of recording which brain hemisphere is working on a particular task and by demonstrating this, will enable the subject to be trained to use their brain more effectively. Such techniques, which formerly could only be performed in a well-equipped laboratory, can now be used as part of curriculum classroom training.

 

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