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Walter Grey Walter

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His life


W. Grey Walter February 19 1910 - May 6 1977 was born in Kansas City, Missouri, in 1910. His parents were originally German/British, from the father side, and American/British, from the mother side. He was brought to England in 1915, and educated at Westminster School and afterwards in King's College, Cambridge, in 1931. He failed to obtain a research fellowship in Cambridge and so turned to doing basic and applied neurophysiological research in hospitals, in London, from 1935 to 1939 and then at the Burden Neurological Institute in Bristol, from 1939 to 1970. He also carried out research work in the United States, in the Soviet Union and in various other places in Europe. He married twice, and had two sons from the first and one from the second. According to his eldest son, Nicolas Walter, "he was politically on the left, a communist fellow-traveller before the Second World War and an anarchist sympathiser after it." Throughout his life he was a pioneer in the field of cybernetics. In 1970 he was in a severe automobile accident and died seven years later on May 6 1977 without fully recovering.

Walter's work on brain waves

As a young man Walter was greatly influenced by the work of the famous Russian physiologist Ivan Pavlov. He visited the lab of Hans Berger, who invented the electroencephalograph, or EEG machine, for measuring electrical activity in the brain. Walter produced his own versions of Berger's machine with improved capabilities which allowed it to detect a variety of brain wave types ranging from the high speed alpha wave s to the slow delta waves observed during sleep.

In the 1930s Walter made a number of discoveries using his EEG machines at Burden Neurological Institute in Bristol. He was the first to correcly locate the source of alpha wave s by triangulation within the occipital lobe of the brain and demonstrated the use of delta waves to locate brain tumours or lesions responsible for epilepsy. He developed the first brain topography machine based on EEG, using on an array of spiral-scan CRTs connected to high-gain amplifiers.

During the Second World War he worked on scanning radar technology and guided missiles , which may have influenced his subsequent alpha wave scanning hypothesis of brain activity.

In the 1960s Walter also went on to discover the contingent negative variation (CNV) effect (or readiness potential ) whereby a negative spike of electrical activity appears in the brain half a second prior to a person being consciously aware of movements which they are about to make. Intriguingly, this effect brings into question the very notion of consciousness or free will, and should be considered as part of a person's overall reaction time to events.

The "turtles"

Dr. Grey Walter and one of his creations

Grey Walter's most famous work was his construction of some of the first electronic autonomous robots. He wanted to prove that rich connections between a small number of brain cells could give rise to very complex behaviors - essentially that the secret of how the brain worked lay in how it was wired up. His first robots, named Elmer and Elsie, were constructed between 1948 and 1949 and were often described as turtles due to their shape and slow rate of movement. The three wheeled turtle robots were capable of phototaxis , by which they could find their way to a recharging station when they ran low on battery power. In one experiment he placed a light on the "nose" of a turtle and watched as the robot observed itself in a mirror.

"It began flickering, twittering, and jigging like a clumsy Narcissus", he wrote. If seen in an animal he argued this "might be accepted as evidence of some degree of self-awareness".

Later versions of the robots were exhibited at the Festival of Britain in 1951.

Walter stressed the importance of using purely analogue electronics to simulate brain processes at a time when his contemporaries such as Alan Turing and John Von Neumann were all turning towards a view of mental processes in terms of digital computation. His work inspired subsequent generations of robotics researchers such as Rodney Brooks, Hans Moravec and Mark Tilden. Modern incarnations of Walter's turtles may be found in the form of BEAM robotics.

Recently, one of the original tortoises was found by Dr. Owen Holland, of the University of West of England, and was restored to order in 1995. A specimen of a second generation turtle is in the collection of the Smithsonian Institution.

Books and articles

  • An imitation of life, Scientific American (1950) 182(5): 4245
  • A machine that learns, Scientific American (1951) 185(2): 6063
  • The Living Brain, New York (1953)
  • Contingent negative variation: An electrical sign of sensorimotor association and expectancy in the human brain, Nature (1964) 203: 380-384
  • Grey Walter: The Pioneer of Real Artificial Life, Holland, Owen E. *Proceedings of the 5th International Workshop on Artificial Life, Christoper Langton Editor, MIT Press, Cambridge, 1997, ISBN# 0-262-62111-8, p34-44.
  • Walter's world, New Scientist, 25/7/98.

External links

  • Machina speculatrix: W. Grey Walter's history and how to reproduce Elsie using Lego.
  • The Gray Walter Picture Archive On-Line. University of West England.
  • The Gray Walter On-Line Archive . University of West England.


A portion of this content from source has been reproduced with permission.
Imitation of Life: A History of the First Robots By: Renato M.E. Sabbatini, PhD
In: Brain & Mind , July 1999.
Reproduced with permission.

Last updated: 02-25-2005 14:39:11