Asymmetric relationshipsAsymmetric relationship(s) are frequently observed in animal as well as human behavior. For example, pecking orderPecking order(s) is a special asymmetric relationship among a group of hens and cocks (e.g., Rushen (Holman in Journal of Mathematical Psychology 20:1–15, 1979)). Asymmetric relationships may become more complicated in humans than in animals. A typical example may be asymmetric sentiment relationships such as one-sided loveOne-sided love and hate among members of informal groupsInformal group in classrooms.