Like a magician our mind tricks us into believing what we see and feel. We only notice that something strange is going on when our expectations are betrayed during the prestige – when the white rabbit is drawn out of the empty hat. Psychology sometimes works in much the same way. After the mind has made us believe in the ordinary, it creates strange cases which point to something bigger going on behind the scenes. One of the most extraordinary illusions is the one of our body. At the final prestige we see people born with phantom penises which no one can see. What was going on behind the scenes?
‘Phantoms’ is what Silas Weir Mitchell called the amputated limbs that their owners could still feel. The most straight-forward explanation simply refers to re-membering. When an amputated limb lives on as a phantom arm one could say that the mind fails to realise the loss and fills in the usual feelings with memories. This re-membering may well explain why some people claim to feel a watch or even clothes on the phantom skin.
It is as if the magician had produced a rabbit out of an ‘empty’ hat and everyone suddenly noticed that the hat was high enough to house it from the start. However, the mind had another trick up its sleeve. Since the initial description of phantom limbs in 19th century amputees, this phenomenon has also been discovered in people who had never been born with limbs to begin with. These so called congenital phantom limbs are very strange because their owners obviously have no memories of limbs. Re-membering cannot explain this.
Perhaps it is time to turn from psychology to neuroscience in our quest to understand this trick. The part of the human brain responsible for limb movements is a well organised bit of cortex which looks very similar across people: the primary motor cortex. When the appropriate bit of my own primary motor cortex once got stimulated with magnetic waves, my index finger twitched. Peter Brugger and colleagues did the same with a woman only known as A.Z.. She was born without arms or legs but reported feeling them nonetheless. Magnetic stimulation of her primary motor cortex made her phantom limbs move. This suggests that the action control mechanism and the brain mechanism responsible for phantom limbs are linked.
Thus, all we know about action control in the human brain can be used to explain away the phantom limb phenomenon. Firstly, the primary motor cortex is at least partly genetically determined, i.e. limb control is part of our genetic make-up whether we’ve got limbs or not. When trying to control limbs which do not exist, the brain may create the illusion of controlling phantom limbs instead. Secondly, some researchers believe that a muscle activation command is not only sent to the muscles but a copy is also sent to the back of the brain. This allows us to react to expected action outcomes even before they have occurred. Phantom limbs may occur because expected actions get misinterpreted as real ones. Thirdly, mirror neurons code for actions seen and actions done. According to this explanation A.Z. saw many people use their limbs and this made her have the illusion that she could do the same, albeit only with phantom limbs instead of real ones.
However, the final prestige defies all these explanations. Something else entirely must be responsible for a phenomenon reported by Vilayanur Ramachandran and Paul McGeoch in 2008: phantom penises. Like phantom limbs they can occur after amputation. Fascinatingly though, they were also reported by female-to-male transsexuals without an artifical penis. Crucially, this cannot simply be put away as ‘wishful thinking’. For one, their phantom penises were not perfect: for some they were shaped in an undesirable way, erected in embarrassing non-erotic situations, or rubbing against the jeans. But more importantly, Western society goes to great lengths to make life as a transsexual seem like an unattractive option. For example, when they were children, two phantom penis owners were taken to a psychiatrist by their puzzled parents to be treated for a penis that did not exist. Why would anyone want to go through this as a child – or indeed through life changing surgery as an adult – if it wasn’t absolutely necessary?
But if being born with a phantom penis cannot be explained by re-membering, brain mechanisms of action control (a penis is obviously not a muscle one can voluntarily control), or wishful thinking – then what lies behind this phenomenon? This final trick of the mind, seemingly the most ordinary sensation of being a man or a woman in a male or female body, defies easy solutions. Ramachandran and McGeoch speculate that hormonal factors before birth could be responsible.
Before any such speculation can be substantiated I can only conclude that this final prestige remains a mystery. Just like an audience member seeing a magician do a trick on a member of the public, I wonder whether I have been tricked as well. Phantom limbs and phantom penises show powerfully that the link between our anatomical body and our body image is a fragile one. The mind is doing all sorts of trickery behind the scenes in order to hide this difference between body felt and body seen. Like with any good magician, one wonders how this trick is actually done.
Brugger P, Kollias SS, Müri RM, Crelier G, Hepp-Reymond MC, & Regard M (2000). Beyond re-membering: phantom sensations of congenitally absent limbs. Proceedings of the National Academy of Sciences of the United States of America, 97 (11), 6167-72 PMID: 10801982
Mitchell, W (1871). Phantom limbs Lippinscott’s Magazine, 8, 563-569
Ramachandran, VS, & McGeoch, PD (2008). Phantom Penises In Transsexuals – Evidence of an Innate Gender-Specific Body Image in the Brain Journal of Consciousness Studies, 15 (1), 5-16
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