Even if most people would probably claim that they have no prejudices against certain groups – the placebo effect reveals the bitter truth. For example, a dummy drug has a weaker effect if it is administered by a woman or by a black person. This is shown by a study carried out in the USA by a team led by Lauren Howe from the University of Zurich. The results were published in the journal »PNAS«.
Under the pretext of an allergy test, prospective doctors or nurses of different sexes and skin colors triggered an allergic reaction in 187 white test subjects and then apparently treated them. However, the cream used was completely ineffective. If a woman applied the apparently helpful ointment, the allergic reaction developed more severely than if a male colleague carried out the same treatment. So the placebo effect was weakened. The skin color of the medical staff also played a role. When a black doctor triggered the allergy, a larger area of the skin blushed than an Asian-looking or white doctor. Also, the placebo cream provided less relief.
“If a doctor doesn’t look like someone who has had that role for most of history — that is, if the doctor isn’t a white male — patients might be less responsive to treatment,” says Howe.
So does this mean that white patients see women as less competent than black people? “Interestingly, the patients had no explicit prejudice against women or black medical professionals,” explains Howe. On the contrary: The participants tried very hard not to be biased, which was also reflected in the doctor-patient relationship. 1,400 volunteers reviewed video clips of the interactions and concluded that the white subjects appeared more polite and interested when dealing with a male or female doctor. “The results illustrate how deep prejudices run,” says Howe.