In our neurobiology class today we watched this video which really impressed me. I am posting the link to it at the end of my rambling. These two girls are conjoined at the head and have what is called a neural, or thalamic bridge. Although they each have their own brains, their thalami (singular = thalamus) are connected to each other. The thalamus is the portion of the brain which receives most of the sensory information from the rest of the body (vision, touch, etc). So, because of this, when one of the girls sees something that the other girl cannot, the second girl knows what the first one is seeing. This works because when the first girl sees the pony, the information is sent to the thalamus and is then processed as the object being a pony. However, because of the bridge between their thalami, the second girl also receives the exact same information even though she is not seeing the pony. This is why she can tell what her sister is seeing even though she herself cannot see it. The same goes for the tickling of the toes by the auntie. I was definitely impressed with the video and how the two girls live together, joined at the head like they do.
Here's the link: Conjoined Twins