In a pioneering experiment, an American team scanned the brain activity of two volunteers watching a video and used the results to recreate the images they were seeing.

Although the results were crude, the technique was able to reproduce the rough shape of a man in a white shirt and a city skyline.

Professor Jack Gallant, who carried out the experiment at the University of California, Berkeley, said: ‘At the moment when you see something and want to describe it you have to use words or draw it and it doesn’t work very well.