Trust can be a tricky thing. No matter how strong the relationship appears to be, if there’s a chink in the trust chain, chances are you’re headed for a break-up. So when a partner cheats, or if you suspect foul play, it can be hard to know whether your instincts are intact or if jealousy has kicked in. According to a new study, the answer could all lie in the eyes of a third-party beholder. Psychologists from Brigham Young University studied 51 graduates (35 women and 16 men) who were romantically involved with another half, and asked them about their relationships, including whether they had been faithful. The researchers then videotaped the couples having conversations and asked third parties to watch the footage. When asked to judge if there had been a case of infidelity, the findings were surprisingly accurate. The study found that third-parties were able to tell in a majority of cases if either partner had cheated during the course of the relationship. Speaking about the study, research leader Nathaniel Lambert said: "I was personally amazed about what could be surmised about people after watching them on a video for just a few minutes. First, I couldn't believe how consistent the observers were with each other at independently rating who they thought were cheating on their romantic partner. “Second, I was surprised by how often they were right on the mark." Lambert said that third-parties were able to pick up on body language, conversational tones and revealing answers from emotional to financial issues the couples were breaking down in their conversations. So the truth of the matter is go with your gut instinct. Or ask your friend around for a dinner party… Study via Marie Claire