David Spiegel, from Stanford University, told the prestigious American Association for the Advancement of Science that he had scanned the brains of volunteers who were told they were looking at coloured objects when, in fact, they were black and white.
A scan showing areas of the brain used to register colour highlighted increased blood flow, indicating that the volunteers genuinely 'saw' colours, as they had been told they would.
'This is scientific evidence that something happens in the brain when people are hypnotised that doesn't happen ordinarily,' Mr Spiegel told delegates.

