列子：Dunbar's number is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships—relationships in which an individual knows who each person is and how each person relates to every other person. This number was first proposed in the 1990s by British anthropologist Robin Dunbar, who found a correlation between primate brain size and average social group size.By using the average human brain size and extrapolating from the results of primates, he proposed that humans can comfortably maintain only 150 stable relationships. Dunbar explained it informally as "the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar".
术语卡
术语：爱情三角理论
印象：用三个维度定义爱情
例子：斯坦伯格 ( Robert Sternbeg ) 用三个独立的维度来定义爱情：亲密、激情、承诺。如果忽略只出现于浪漫关系中的激情元素，另外的两个元素说明了情感关系有两个关键点，那就是实际的亲密和感受的亲密。这两个点，在灵长类紧密关系的模型中得到了充分的印证：实际的亲密反映在相互梳理上，而作为一个更模糊的概念，感受的亲密则反映在认知上。