How does your best friend feel when people act needy¹（贫困的） ? Or, about people being dishonest? What do they think when others seem uncomfortable in social situations? According to an upcoming study in Psychological Science, a journal of the Association for Psychological Science, if you don't know – your relationship may pay a price. There are lots of ways to know someone's personality. You can say "she's an extrovert²" or "she's usually happy." You may also know how he or she reacts to different situations and other people's behavior. "It's a more detailed³ way of understanding personality," says Charity A. Friesen, a graduate student at Wilfrid Laurier University, who co-wrote the new paper with Lara K. Kammrath. "You might know the person is extroverted⁴（性格外向的） when they're out with their friends but more introverted（内向的） when they're in a new situation." When a person is faced with one of a list of situations, then how does he or she behave? Friesen identifies this as an "if-then profile."

Friesen and Kammrath recruited university students to take part in the study. Each student was asked to get a friend to participate in the study with them. Then each of the participants individually filled out an online survey. This included a list of "triggers"—descriptions of behaviors that someone might find annoying. One example was the word "skepticism" which was described as when someone is overly disbelieving of information that he/she receives, when he/she questions things that are generally accepted, or when he/she is very hard to convince of something. The list also included gullibility⁵（轻信，易受骗） , social timidity, social boldness, perfectionism, obliviousness⁶ and several dozen other possible triggers. For each behavior, each respondent answered a question about how much this triggers them and how much it triggers their friend.

Some people knew their friends' triggers well; others had almost no idea what set their friends off. And that made a difference to the friendship. People who had more knowledge of their friend's if-then profile of triggers had better relationships. They had less conflict with the friend and less frustration⁷ with the relationship. Other research has shown that it's not that hard to come up with a list of traits that describe someone; casual acquaintances（熟人，相识） can do it. "But, if I'm close to someone, I can really start to learn the if-then profiles, and that's what's going to pay off in my relationship," Friesen says.