When we ponder the really big questions in neuroscience, it's unlikely that the first one that springs to mind is “Why can't I tickle myself?” Yet researchers at the University of Wales in Swansea claim that the answer to this question could have important ramifications for the study of consciousness.

The research team, led by Dr Mark Blagrove, used a “2-foot long, electronically-controlled 'tickler'” (icwales.icnetwork.co.uk, 5 April 2004) to test the ability of volunteers to tickle themselves when they were fully awake, or had just woken from rapid eye movement (REM) or non-dreaming sleep. They found that if the volunteers used the machine to tickle themselves just as they were waking from REM sleep, the sensation was as intense as if someone else was doing the tickling, but this was not the case if they were awake or had just woken from non-dreaming sleep.

Blagrove compares the dream state to the hallucinatory state in schizophrenia: “People with schizophrenia can successfully tickle themselves because they produce hallucinations, but think that what they see is real ... not actually produced by them. REM sleep allows you to believe that the events of the dream are real, that you are not producing them, and this ... carries over for a few minutes when you are awake” (BBC News Online, 5 April).

So, other than giving hope to people who have a burning desire to be able to tickle themselves, what are the implications of this research? Blagrove says: “It is quite an important thing in terms of when do people feel in control of what they are doing, and when do they think things are being done to them. It is all to do with whether you can monitor what you are doing to yourself” (BBC News Online).