Here’s an interesting article linked from io9 about twins who are linked at the head, sharing brains, having separate personalities and cognitive traits, but sharing sensory input and even possibly thoughts.
Being a psych major, this is something I can geek out about. It’s really cool to be able to see this kind of occurrence that blurs lines between individuality and give us more insight into what our brains really do. I’m better at thinking than voicing my thoughts, so I’ve just been perusing the comments on that article and gleaning what I can. Sometimes the internet can be very insightful :3