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 a black person. This is shown by a study conducted in the USA by a team led by Lauren Howe from the University of Zurich. The results were published in the scientific journal "PNAS".
Under the pretext of an allergy test, prospective doctors or nurses 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 helping ointment, the allergic reaction developed more than when 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. If a black doctor triggered the allergy, a larger area blushed on the skin than with an Asian -looking or white doctor. In addition, the placebo cream provided less relief.
"If a doctor doesn't look like someone who's held that role for most of history – that is, if the doctor isn't a white male – it could be that patients are less responsive to treatment," Howe says.
So does that mean that white patients assess women and black people as less competent? "Interestingly, patients had no explicit prejudices against women or black doctors," explains Howe. On the contrary: the participants tried very hard not to be biased, which was also reflected in the doctor-patient relationship. 1400 volunteers evaluated video clips of the interactions and came to the conclusion that the white test subjects looked more polite and more interested if they had to do with a doctor. "The results illustrate how deep prejudices sit," says Howe.
