Whether it was a sports competition or a political election, we have all rooted for the underdog at one point. Was this because we were truly rooting for that team or person, or did we do it because we are predisposed to root for the underdog, regardless of who or what it is? A group of researchers attempted to answer this question with a study involving infants, squares, and circles. As the circle appeared to pursue, bump, and smash the yellow square, the researchers observed the reactions of the infants. Some 16 out of 20 infants reached out for the yellow block. Researchers believe that this may be a sign of human beings' predisposition to root for the underdog.
The study, published in PLOS ONE journal in 2013, also tested the infants' preference between an aggressor, a victim and a bystander-- in this case, a red cylinder. They found that infants preferred the bystander over the aggressor and the victim over the bystander. Researchers are not completely certain whether these results mean that humans are naturally predisposed to sympathize with the victim. But they do believe that the human brain is able to establish causation and place a negative value on aggression at the age of ten months.
Other researchers offer a completely different interpretation of this phenomenon. They don't believe that humans root for the underdog; instead, they believe that we root against the dominant entity.
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I think it has to do with the predisposition of our brains to find symmetry. The only way to achieve symmetry is to support the underdog.