Although Dr. William Grey Walter is most known for his Turtle robots, he is a neurophysiologist first. So it's better to study his researches in fields of neural system before we move on to his studies in robots. I found wiki lists two chapters for Dr. W.Grey Walter: Brain Waves and Robots. Here I will also add other materials from wild searches in the google.

Dr. W.Grey was born in Kansas City, Missouri, in 1910. He's educated mostly in Britain. He made a self-introduction in the book titled “Discussions on Child Development” from which we can see how he was influenced by the Pavlovian Theories in his early studies. Dr. W.Grey carried out long time researches to improve the technologies of electroencephalography(EEG), or the brain waves, for measuring electrical activity in the brain. During this period, he “devoted a number of years to the study of organic lesions of the nervous system, to relearn neuroanatomy and apply it to” some studies. By these efforts, he made some important discoveries about the high speed alpha waves and slow delta waves. He also demonstrated the use of delta waves to locate brain tumors.