1. Skip to content
  2. Skip to main menu
  3. Skip to more DW sites

Study: Patients' physical responses influenced by biases

A study has found that white patients experience a weaker placebo effect when treated by non-male, non-white doctors. Unconscious biases are likely to blame.

A white, male doctor's hand holding pill sleeves
A new study shows: The placebo effect is weaker when the doctor is not a white man.Image: Robert Kneschke/Zoonar/picture alliance

The US healthcare system has been changing for years, with ever more diverse people working in the field. The high percentage of white male doctors is declining.

But is this shift also reflected in peoples' mentality? Researchers at ETH Zurich wanted to find out by conducting an experiment involving 187 exclusively white subjects of various ages who participated in a faux allergy test. Their result: A placebo lotion administered by a white man is more effective than if applied by someone of a different gender or race.

Even when subjects held no overt prejudices against non-white, non-male doctors their physical response revealed otherwise. Placebo effects observed were far less pronounced when non-white, female doctors were involved.

Thoughts lead to physical reactions

A placebo effect, simply put, results when someone believes in the healing properties of a drug or treatment, which in turn stimulates the hypothalamus, a part of the brain that has many crucial functions such as regulating emotional responses. Positive expectations can, therefore cause physical responses.

The study, published in Proceedings of the National Academy of Sciences(PNAS), a peer reviewed journal, says subjects were first given a laboratory-induced allergic skin reaction and then treated with a placebo lotion. They were told the location has a soothing quality, when in reality, it had no effect whatsoever. Subjects were treated by either a male or female doctor of either Asian, Black or white ethnicity.

A stethoscope next to a symbol of a man
Placebo effects are both psychological and physical Image: Channel Partners/Zoonar/picture alliance

Subjects showed very different responses to the standardized experiment, depending on who caused the allergic reaction and applied the placebo lotion.

Researchers observed that whenever a female doctor administered the placebo cream, subjects would show a stronger allergic reaction than if treated by a male doctor.

Subjects also showed different responses when treated by doctors of different races. Whenever Black doctors caused an allergic reaction, the reaction would affect a larger area of skin than when provoked by an Asian or White doctor. Similarly, the placebo lotion proved less effective when applied by a Black doctor.

Unconscious prejudices

These unconscious physical responses show subjects held unconscious prejudices towards non-white, female healthcare providers.

"If their doctor doesn't look like the kind of person who has been in that role for most of history — that is, if the doctor is not a white man — then the patients may be less responsive to treatment from that doctor in terms of their immediate, physical response to the treatment," explains lead author Lauren Howe.

The different responses were noteworthy, says Howe, because subjects were evidently trying to be unbiased towards doctors. 1,400 volunteers who were shown video footage perceived the white subjects to be more interested and polite when treated by female or Black doctors.

Placebos and nocebos - new insights

07:13
Placebos and nocebos - new insights

But subjects' physical reactions still told a different story. The authors sum up their findings saying they "illustrate how notions of race and gender can influence patients beneath the surface — literally under the skin — despite their professed intentions and even to their own detriment."

This article was translated from German