How sleep training can rid your brain of sexism and racism

Study appears to show that sleeping 'provides a unique window for altering fundamental beliefs'

(Image credit: Wikimedia Commons )

Innermost prejudices about race and gender can be eliminated using "sleep training", according to scientists in Illinois.

A study carried out at Northwestern University found that biases can be altered during sleep. It did not target overt sexism or racism, but rather implicit biases arising from long-term socialisation and frequently reinforced by mass media. For example, previous research has shown that 80 per cent of people have a bias against the elderly and that people often have a preference for white faces over black faces.

"These biases are well-learned," said Xiaoqing Hu, who led the study. "They can operate efficiently even when we have the good intention to avoid such biases. Moreover, we are often not aware of their influences on our behaviour."

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In the Illinois study, participants took part in two Pavlovian-style conditioning exercises while they were awake, one showing female faces with words linked to maths or science and another showing black faces with pleasant words such as "cheer", "smile" and "honour".

Two distinctive sounds were played during the tasks. Then the sounds were played again while the participants took a 90-minute nap.

According to the researchers, the auditory cues partially undid racial and gender bias, with the effects still evident a week later. Before the nap, bias scores fell slightly but for those who listened to the sound cues during sleep the scores fell a further 56 per cent.

Hearing the sound replayed repeatedly during sleep helps to consolidate memories, transferring them from short-term storage to long-term storage in the brain, said the scientists.

Comparing the study to "sleep teaching" in Aldous Huxley’s Brave New World, The Guardian says the findings "appear to confirm the idea that sleeping provides a unique window for accessing and altering fundamental beliefs".

A similar strategy could be used to reduce other kinds of biases or to tackle bad habits such as smoking and over-eating, said the study's authors.

In an accompanying commentary published in Science, two psychologists said the findings highlight "the breadth of possible applications to permanently modify any unwanted behaviour by targeted memory reactivation during sleep".

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