Thank you. You motivated me to read the paper.
"Swapping did not happen when the touches were dissimilar."
"Increased stress was measured when threatening the foreign body with knives."
If the Washington Post had included sth. like these at the appropriate places, it would have greatly improved the article. We often lament the public's lack of basic understanding of scientific methodology, don't we? (And we lament slashdotters who post before following links, I know.)
If I understand the discussion in the paper correctly, they could trick the mind because it takes shortcuts (it uses historical information as presuppositions) when assembling the whole experience of the body image. I wonder how well the swapping works when they modify the foreign body (with longer legs, a tail, etc.), or the apparent laws/parameters of physics it is subjected to. My guess is the latter has the best chance of working.
Still, I cannot imagine the experience of body-swapping. Sounds exciting.