A masterly scientific populariser, pioneer in artificial intelligence and internationally renowned authority on the psychology of perception has died.
Richard Gregory was born in London on 24 July 1923, the son of an astronomer, and brought up, he once wrote, with "optical instruments and the importance of making observations" as a constant in his life.
After school and service in the RAF during the war, he went to study moral sciences at the University of Cambridge in 1947, an experience he later said he found "intoxicating beyond description". He was to remain there for 20 years, as a researcher in the Applied Psychology Unit and as a demonstrator and lecturer in the department of experimental psychology. Much of his subsequent work arose out of his special senses laboratory and his study of a blind 52-year-old man who slowly learned to see after a corneal operation.
In 1967, Professor Gregory helped set up the department of machine intelligence and perception at the University of Edinburgh - initially in a laboratory that had been a church, though permission was withdrawn when news got out that they were planning to build a robot. He was an early enthusiast for research into artificial intelligence and once said that his goal was to create a machine that could "draw interesting analogies and make puns".
In his final post, Professor Gregory became professor of neuropsychology and director of the brain and perception laboratory at the University of Bristol. Much of his research explored the notion that perceptions can be seen as predictive hypotheses, but it also held practical applications for the treatment of Parkinson's disease.
Professor Gregory was deeply committed to popularising science and delivered the Royal Institution Christmas Lectures on "The Intelligent Eye" in 1967 and was largely responsible for both the hands-on Bristol Exploratory science centre (now Explore@Bristol) and another at Herstmonceux Castle in Sussex. He was also a fluent and prolific writer whose books include Eye and Brain: The Psychology of Seeing (1966), Illusion in Art and Nature (with art historian Ernst Gombrich, 1973), The Oxford Companion to the Mind (editor, 1987) and Seeing Through Illusions (2009).
Iain Gilchrist, professor of neuropsychology at Bristol, said: "When I popped into his office, even up to a couple of weeks ago, he was always excited about something. He could get to the heart of any topic and talk about it clearly and lucidly. His enthusiasm recharged your batteries."
Professor Gregory died on 17 May and is survived by his long-term partner, Priscilla Heard, and two children from an earlier marriage.