New research conducted by Kiley Hamlin as a graduate student at Yale University, now a professor at the University of British Columbia, published in the journal Psychological Science on March 12, 2013, indicates that infants display social bias as early as nine months of age.
The conclusions were the result of experiments where children from nine months to 14 months of age viewed a set of films that showed puppets displaying a common real world scenario. The puppet show showed a character that lost a ball and wanted the ball back. The children watched two different scenarios where a helpful puppet returned the ball and another puppet kept the ball. A second series of the same puppet show showed a puppet of different physical appearance than the puppet that lost the ball performing the same two behaviors.
The children preferred the puppet that returned the ball to a puppet that looked the same. The children preferred the character who harmed the dissimilar puppet over the character who helped him.
The researchers conclude that some basis for social bias is innate and potentially genetic. The scientists further elaborate that such innate bias does not approach the realm of xenophobia or racist behaviors.
The preference for individuals like oneself may be a protective evolutionary adaptation that is much more ancient than modern man and genetically unavoidable.
The overall objective of the research was to identify the basic antisocial behaviors and prepare an early education regimen that ameliorates some of the innate response to physical differences as displayed by infants.
The films the children viewed can be seen here.