This is a podcast from the archives of the BBC Reith Lectures.

This lecture in the series Mechanics of the Mind, given by Colin Blakemore, was originally broadcast in 1976.

In Cambridge, Massachusetts, in London, England, and in Lyon, France, there are men who can see but don't perceive.

They have eyes that function, but they themselves are unaware of the things that their eyes can see and on which they are able to act.

These men all have brain injuries at the back of the cerebral hemispheres in the part called

the visual cortex, which receives messages from the eyes.

In the middle of the last century, a Frenchman, Marie-Jean-Pierre-F-F-Lorrent, provided the first real

experimental evidence that the cerebral cortex is responsible for so-called higher functions of the

mind. Although he spoke of faculties like will

and intellect, his experimental subjects were animals, not people. Like Aristotle, Galen and

Leonardo before him, Florent had intuitive trust in the continuity of biological mechanisms,

which led him to extrapolate from animals to man.

Shortly before his death in 1867,

Florent wrote in opposition to Darwin's new theory of natural selection.

But it was that very theory that made legitimate his own experimental paradigm.

Floreen worked by studying the consequences on an animal's behavior of damage to its brain.

Animals deprived of their cerebral lobes, he concluded,

have neither perception nor judgment, nor memory, nor will.

The cerebral lobes are therefore the exclusive seat of all the perceptions

and all the intellectual faculties. Hermann Monk in Berlin first realized that small injuries to the

surface of the cortex could render an animal apparently blind or seemingly deaf.

But Munk also made the remarkable discovery that these mind-blind and mind-deaf animals

...