Stockholm syndrome is a condition in which hostages develop a psychological bond with their captors during captivity. Emotional bonds may be formed between captors and captives, during intimate time together, but these are generally considered irrational in light of the danger or risk endured by the victims. Stockholm syndrome has never been included in the Diagnostic and Statistical Manual of Mental Disorders or DSM, the standard tool for diagnostic of psychiatric illnesses and disorders in the US, mainly due to the lack of a consistent body of academic research. The syndrome is rare: according to data from the FBI, about 5% of hostage victims show evidence of Stockholm syndrome.