Killen obtained her Ph.D. in Developmental Psychology from the University of California, Berkeley, where she was a NIMH Predoctoral trainee.
Research guided by the theory has shown that children and adolescents use multiple forms of reasoning, morality, group identity, and psychological knowledge when making decisions and evaluating intergroup contexts.
Killen received funding from the National Science Foundation and the National Institutes of Child Health and Human Development to conduct randomized control trial (RCT) of a program developed by her team designed to reduce prejudice and bias and promote positive intergroup friendships in childhood.
[1] [2] In 2011-2012, Killen and her research team were commissioned by Anderson Cooper at CNN AC360 to conduct a study on children's racial biases which aired in April 2012, and won an Emmy Award for Outstanding News and Analysis, October 1, 2013.
[3] Killen served on the brain trust initiative in the education unity for the National Museum of African American History and Culture in Washington DC.