The finding comes from a study that is to be published this week in the Journal of Experimental Social Psychology. The research used a virtual reality simulation and was prompted by a number of mistaken shootings of unarmed blacks by police officers in recent years. It was directed by Anthony Greenwald, a University of Washington psychologist who examines the unconscious roots and levels of prejudice.
Although the subjects in this study were college students, Greenwald said there is every reason to believe that police officers have the same prejudices or psychological perceptions about race as students. He bases that conclusion on data collected from hundreds of thousands of people who have taken versions of the Implicit Association Tests (IAT), including one that measures unconscious attitudes about people and weapons. The majority of people who have taken the tests exhibit some form of unconscious racial, ethnic, gender or age prejudice or stereotype. The IAT was created by Greenwald, and developed in collaboration with Mahazarin Banaji, a Harvard University psychology professor and Brian Nosek, a University of Virginia assistant professor of psychology.
"Police receive training to make them more sensitive to weapons, but they don't get training to undo unconscious race stereotypes or biases," said Greenwald. "There are some very sophisticated simulators police officers can train on, but they are geared to weapons, not race. Bias awareness training could give officers the chance to discover and counteract automatic stereotypes that can interfere with the best performance of their duties."
In the study, more than a hundred college students, predominantly white or Asian, participated in two experiments in which they were asked to play the role of a plainclothes police officer. Their job was to take quick action in response to three categories of simulated potential targets: criminals, fellow officers and citizens. Students were given less than a second to respond - eight-tenths of a second in experiment one and nine-tenths of a second in experiment two - to figures that popped out from behind one of two dumpsters. The subjects were instructed to "shoot" at criminals by pointing the mouse at them and then left clicking, to send a safety signal to fellow officers by pressing the spacebar, and to make no response to citizens.
All of the targets were dressed similarly in casual clothes. Subjects could distinguish police officers and criminals, both of whom held guns, from citizens, who carried harmless objects - a camera, beer bottle or flashlight. The only feature that distinguished police officers from criminals was race. Each subject responded to two variations of the simulation. In one, white targets were criminals and blacks were police officers. In the other, the roles were reversed with blacks as criminals and whites as officers.
Greenwald said the time pressure subjects faced was comparable to conditions police officers sometimes encounter.
"Actually, police officers try to do whatever they can so as not to be forced to respond this quickly. But there are situations that do require them to respond this rapidly," he said
Data from the two experiments indicated that the subjects had greater difficulty distinguishing weapons from harmless objects in the hands of blacks than whites. They also were more likely to shoot when the target person was black, regardless of knowing what was in the person's hand. In the two experiments, whites were wrongly "shot" 26 percent of the time while blacks were wrongly "shot" 35 percent of the time, which is statistically significant.
The UW researchers looked at perceptual sensitivity or their subjects' abilities, in this case, to distinguish a weapon from a harmless object, and their response bias, or readiness to respond by shooting more readily at blacks than whites. Greenwald likened these processes to baseball, where perceptual sensitivity would be a batter's "eye" that tells a ball from a strike and response bias would be the readiness of the batter to swing at anything.
The study is the third in recent months to produce similar findings, but involved a task that may have come closer than the others to model the complexity of natural situations.
"The subjects were on edge because of the time pressure to respond quickly or do nothing in the case of civilians," said Greenwald. "The stress we created is like that of facing a weapon in a video game but it is not the same as the stress faced a by the police officer on the street. Ours is an analog of a high-stress situation of what an officer might encounter. In more realistic simulations for weapons training there are reports of officers with heart rates approaching 200 beats per minute.
"The practical value of our work is for people who manage police on the beat. Our studies and the previous ones lead to the conclusion that we need to look at what kind of training officers are receiving and what kind of training is needed to eventually overcome race-influenced errors that have resulted in blacks being hugely over-represented among victims of mistaken shootings by police."
Co-authors of the study are Mark Oaks, a psychology doctoral student, and Hunter Hoffman, a research engineer in the UW's Human Interface Technology Laboratory where the virtual reality simulation was created. The National Institute of Mental Health funded the research.
People may take the IAT test that measures unconscious attitudes about people and weapons at a Web site operated by the Southern Poverty Law Center at: http://www.
For more information, contact Greenwald at 206-543-7227 or firstname.lastname@example.org. He will be in Santa Fe, N.M., July 15-22 and can be reached at 505-984-1420.