The majority of people overestimate the presence of a minority in social settings, including members of the minority themselves, researchers from the Hebrew University of Jerusalem (HU) have found.
The research, which was published on Saturday in the peer-reviewed journal Proceedings of the National Academy of Sciences, also found that this phenomenon is likely to stymie attempts to make society more equitable, as it causes less support for diversity-promoting policies.
Lead researcher Professor Ran Hassin from the Psychology Department and The Federmann Center for the Study of Rationality at HU, said he thinks the study will have a real impact.
"I believe that our work has immediate and real-life implications," he said. To counteract this bias, he suggested two things must be done to improve decision making: "The actual numbers of the minority need to be made known and people need to understand how they are affected by this cognitive bias. But being aware of the diversity illusion is just the first step - we also need to be motivated to fix it, then we can move towards the implementation of better policies."
In the first experiment, involving students at HU, where Jewish Israelis have a significant majority over the 12 percent of students who are Arab Israelis, students were told to remember times that they walked through the university's main hallway and estimate what percentage of the student body was Arab-Israeli.
Both Jewish and Arab-Israeli students overestimated, with Jewish students guessing 31 percent and Arab-Israeli students guessing 35 percent.
"At first, we couldn't believe the results, so we ran the same experiment several times," said postdoctoral student Dr. Rasha Kardosh, who first suggested the research project.
The experiment was repeated in several other instances, such as one in which American participants looked at a grid made up of 100 students' faces, 25% of whom were African American. Both white and African American respondents overestimated the minority, guessing that over 40% of the faces were of African American students.
Kardosh explained the phenomenon is caused by the fact that "our cognitive system switches its focus to what it doesn’t expect. Just think of walking through the vegetable section of a supermarket and suddenly seeing a bottle of laundry detergent among the potatoes."