I've always been interested in the possibility of a pair of conjoined twins, joined at the head, being able to read each other's thoughts, react to stimuli that one of them can't see/hear/feel, and being unable to keep secrets from one another. Until recently, every pair of conjoined twins I learned about said that they are very much two different people with different personalities and emotions.
Then I read a wikipedia article about Krista and Tatiana Hogan. It was a newspaper article, unfortunately, rather than a piece in a scientific journal, but the description of the girls is exactly what I had been thinking of:
If one girl is blindfolded, she can see what her sister sees. They share thoughts. They can't keep secrets from one another. If one of the girls hurts a limb that she controls, the other girl feels the pain as well as the girl who actually hurt herself.
I'm curious as to whether this phenomenon has been observed before. How common is it for conjoined twins to share thoughts, see through each other's eyes, hear through each other's ears, and be incapable of keeping secrets from one another? Has it ever been observed before this pair of twins?