When WGBH Boston Public Radio’s investigative reporter Phillip Martin meets “Qui” and “Phong,” two Vietnamese teenage girls, they are laughing. You wouldn’t know they had just survived a year in which Martin says they “were kidnapped, severely beaten, raped and sold into slavery by organized human trafficking rings.” While their jovial behavior following such horrific experiences may seem inconsistent to Westerners, even puzzling, aspects of Vietnamese culture must be fully explored to help understand their attitudes.