WASHINGTON (AFP) - Many Americans consider that mixed-race people like President Barack Obama belong to their minority parent group, which is still widely seen as socially inferior to whites, a study released Thursday shows. The authors of the study published in the Journal of Personality and Social Psychology say Americans still apply the one-drop rule, also known as hypodescent, which dates to a 1662 Virginia law on the treatment of mixed-race individuals, when deciding how to categorize a person of mixed race. Hypodescent against blacks remains a relatively powerful force within American society, said James Sidanius, professor of psychology and of African and African American studies at Harvard and a co-author of the study. The findings of the study reflect just how entrenched is Americas traditional racial hierarchy, which assigns the highest status to whites, followed by Asians, with Latinos and blacks at the bottom, the authors said. Our work challenges the interpretation of our first biracial president and the growing number of mixed-race people in general as signaling a color-blind America, said lead author Arnold Ho, a doctoral student in psychology at Harvard. Obamas father was Kenyan and his mother was white American. Ho, Sidanius, Mahzarin Banaji of Harvard and Daniel Levin of Vanderbilt University asked study participants to look at computer-generated pictures of mixed race people and say if they thought they were more minority or white. Using face-morphing technology that presented faces ranging from five percent white to 95 percent white, they found that individuals who were a 50-50 mix of either black-white or Asian-white were almost never identified by study participants as white. Black-white biracials had to be 68 percent white before they were perceived as white, while Asian-white biracials had to be 63 percent white. Whites and non-whites were equally likely to assign biracial individuals to lower-status groups, found the study. The United States is already a country of ethnic mixtures, but in the near future it will be even more so, and more so than any other country on earth, said Banaji, a social ethics professor at Harvard. When we see in our data that our own minds are limited in the perception of those who are the products of two different ethnic groups, we recognize how far we have to go in order to have an objectively accurate and fair assessment of people, he said. Ho said the persistence of hypodescent serves to reinforce racial boundaries rather than moving us toward a race-neutral society.