Following the outbreak of war, he went up to Trinity College, Cambridge, as a medical student, though he technically read Natural Sciences, which was the normal thing for medical students at Cambridge at the time.

He won a Rockefeller studentship to finish his clinical studies at Harvard Medical School, where he went after spending a year at the Medical Research Councils lab in London at Mount Vernon, working on problems of diving in relation to the war.

It was at Harvard that, with two fellow medical students, he first carried out research on vision, publishing papers on the effect of magnetic fields on the eye and on dark adaptation and light effects on the electric threshold of the eye.

By the time he returned to Britain, although he completed his medical training at University College Hospital, London, it was clear that he wanted to continue as a research neurophysiologist, and he returned to Cambridge to study Neurophysiology under Edgar (later Lord) Adrian.

Barlow was a fellow at Trinity College (1950-54), and a Fellow and lecturer in Physiology at Kings College, Cambridge (1954-64). In 1964 he crossed the Atlantic to take up an appointment as Professor of Physiology at the University of California, Berkeley.

There he researched many aspects of the physiology and psychology of vision, much of it in collaboration with Bill Levick. Among other things, he discovered that certain retinal cells fire signals when light passes over them in one direction but not in the opposite direction a discovery which stimulated enduring interest in the cellular mechanism behind this directional selectivity, which is now seen as the basis of motion perception.

Later, working with Colin Blakemore and Jack Pettigrew, Barlow discovered the brains mechanism of stereo vision by showing that signals from the two eyes converge on single cells in the visual cortex that respond to specific locations in 3D space.

In 1973 he returned to Cambridge, where he was Royal Society Research Professor of Physiology with a fellowship at Trinity College.

Soft-spoken, but resolute in his opinions and endlessly curious about the natural world, Barlow continued to write about the brain, working in his department and visiting Trinity well into his nineties. His definition of intelligence was the art of good guessing. He continued to be a presence at national and international meetings, taking great pleasure in meeting and educating younger scientists. He supervised the training of more than a dozen doctoral and postdoctoral students, and exerted a broad influence on thinking in the field through their influence as well as his own.

Barlow was elected a Fellow of the Royal Society in 1969 and was awarded the Societys Royal Medal in 1993. In the same year he received the Australia Prize. He won the 2009 Swartz Prize from the Society for Neuroscience and the first Ken Nakayama Prize from the Vision Sciences Society in 2016.

Barlow married first, in 1954, Ruthala Salaman. The marriage was dissolved in 1970, and in 1980 he married, secondly, Miranda Weston-Smith, who survives him with their two daughters and a son, and four daughters from his first marriage.

Professor Horace Barlow, born December 8 1921, died July 5 2020

Excerpt from:
Professor Horace Barlow, neuroscientist who did groundbreaking work on visual perception obituary - Telegraph.co.uk