Free Paranormality: Why we see what isn't there by Richard Wiseman Page A

an object, or a photograph), and was asked to psychically transmit the information to the receiver. No evidence of telepathy emerged from either the twins or the siblings.  
    In the second part of the experiment, Blackmore asked the senders to transmit the first number that came into their mind, make any drawing that appealed to them, and choose which of four photographs to send. The results suddenly changed. As predicted by the ‘twin telepathy is due to similarity’ hypothesis, there was a sudden surge in the twins’ performance. For example, when asked to think of a number between one and ten, 20 per cent of the trials involving twins produced the same number compared to just 5 per cent of those with the siblings. For the drawings, the twins again scored well, exhibiting a 21 per cent success rate compared to the siblings’ 8 per cent.  
             In short, the evidence indicates that twin telepathy is due to the highly similar ways in which they think and behave, and not extra-sensory perception.  
    However, Blackmore is perhaps best known in   sceptical circles for her work explaining out-of-body experiences. She took as her starting point the notion that the feeling of being located inside your body is an illusion created by your brain on the basis of incoming sensory information. Then, in the same way that a rather weird set of circumstances involving a dummy hand or a virtual reality system can cause people to believe that they are elsewhere, Blackmore wondered whether an equally strange set of circumstances might cause people to think that they had floated away from their bodies. Sue focused her attention on two elements that were central to most OBEs.
    The first principle can be illustrated with the help of the image below.  
     

     
    Fix your eyes on the black dot in the centre of the image and stare at it. Providing that you are able to keep your eyes and head relatively still you will find that after about 30 seconds or so the grey area around the dot will slowly fade away. Move your head or eyes and it will jump right back again. What is going on here? It is all about a phenomenon referred to as ‘sensory habituation’. Present someone with a constant sound, image, or smell and something very peculiar happens. They slowly get more and more used to it, until eventually it vanishes from their awareness. For example, if you walk into a room that smells of freshly ground coffee, you quickly detect the rather pleasant aroma. However, stay in the room for a few minutes, and the smell will seem to disappear. In fact, the only way to re-awaken it is to walk out of the room and back in again. In the case of the illustration above your eyes slowly became blind to the grey area because it was unchanging. This exactly same concept can result in the so-called ‘hedonistic treadmill’, with people quickly getting used to their new house or car, and feeling the need to buy an even bigger house or better car.  
    Blackmore speculated that this process was also central to OBEs. People tend to experience OBEs when they are in situations in which their brains are receiving a small amount of unchanging information from the senses. They are often robbed of any visual information because they have their eyes shut or are in the dark. In addition, they usually don’t have any tactile information because they are lying in bed, relaxing in the bath, or are on certain drugs. Under these circumstances the brain quickly becomes ‘blind’ to the small amount of information that is coming in, and so struggles to produce a coherent image of where ‘you’ are.  
    Like nature, brainsabhor a vacuum, and so start to generate imagery about where they are and what they are doing. That is part of the reason why people are more likely to have images flowing through their mind when they shut their eyes, are in the dark or take drugs. Blackmore hypothesized that certain types of people would naturally find it easy to imagine