How to Run a Con (Psychology Today Blogs) [dead link]
…THOMAS is a powerful brain circuit that releases the neurochemical oxytocin when we are trusted and induces a desire to reciprocate the trust we have been shown–even with strangers.
The key to a con is not that you trust the conman, but that he shows he trusts you. Conmen ply their trade by appearing fragile or needing help, by seeming vulnerable. Because of THOMAS, the human brain makes us feel good when we help others