George Goethals, who holds the E. Claiborne Robins Distinguished Professorship in Leadership Studies, and Scott Allison cited in MiNDFOOD for research concerning whether underdogs are supported and why they hold such appeal. 

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Regardless of the scenario presented, whether sporting or political, the results found that people tend to support underdogs in competitive situations. Goethals and Allison found this was true even for inanimate objects: test subjects championed the “underdogs” even when they only existed on computer screens.

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Professor, E. Claiborne Robins Distinguished Professorship in Leadership Studies
Presidential Leadership
Peer Interaction and Performance
Heroes