In the early nineteenth century, Sigmund Freud studied nonverbal cues to detect deception about a century ago. Freud observed a patient being asked about his darkest feelings. If his mouth was shut and his fingers were trembling, he was considered to be lying. Freud also noted other nonverbal cues, such as drumming one's fingers when telling a lie. More recently, scientists have attempted to establish the differences between truthful and deceptive behavior using a myriad of psychological and physiological approaches. In 1969, Ekman and Friesen used straightforward observation methods to determine deceptive non-verbal leakage cues, while more recently Rosenfeldet et al. used magnetic resonance imaging (MRI) to detect differences between honest and deceptive responses.