The Ego Trick (baggini, Julian) / quote 22 of 254
Split brains and two centres of awareness
Because normally the corpus callosum allows the two hemispheres to communicate, this presents no practical difficulty for most people. But the corpus callosum had been severed in Sperry and Gazzaniga’s patients, so this information exchange could not occur. That meant that if you controlled carefully which hemisphere received information from the environment, you could effectively make one hemisphere aware of something that the other was not. What is astonishing about this is that for this to be possible, there would have to be two centres of awareness in the individual concerned. But isn’t the very definition of a self that of a single, unified subject of awareness? Commissurotomy therefore seems to show that selves can be divided – at least temporarily – or that they needn’t have just one centre of consciousness after all.