Want to lose your biases while you sleep? Science may be able to do it

No matter how openminded you think you are, you’re chock-full of what scientists call implicit biases — prejudices you don’t even realize that you have that color your actions.

But a fascinating new study suggests that these biases can be cut down in your sleep. By having subjects go through a biasdiminishing exercise just before taking a nap — during which the things they’d just learned were cued up by special sounds — researchers were able to lower their biases up to a week after the fact. The results were published Thursday in Science.

Xiaoqing Hu, lead author of the study and a postdoctoral researcher at the University of Texas at Austin, was working on ways to diminish implicit biases, like unconscious feelings of racism and sexism, when he happened to read an article on sleep research. Other scientists were finding evidence that sleep could help solidify and strengthen memories.

Would it work, he wondered, to insert the “memory” of a broken bias?

After testing implicit biases against black people and women using a standard experiment, Hu and his colleagues ran a procedure meant to reverse those biases. During this activity, the 40 subjects — male and female college students — were asked specifically to make face and word pairings that went against implicit biases: They were told to match female faces to words associated with the sciences and math, not art, and to match black faces with positive words.

This is a common trick for reversing bias, and it worked. But what happened next was much cooler. Every time one of those test subjects clicked an association that reversed bias (pairing a female face with a science word, for example) a particular tone sounded in the background. There was a different tone for making a pairing that fought implicit racial bias.

After their testing, the subjects were asked to take a 90-minute nap. Meanwhile, some of them were cued with one of the two tones they’d heard during the experiment. The idea here is that the sound primes the brain to focus on the memory of playing the game, giving anything learned during the session a boost.

The subjects who heard tone cues during their naps showed a 50 percent reduction in their baseline bias after waking.

And a week later, when subjects who hadn’t heard tone cues had slid back to their baseline level of bias, those who’d heard the tones in their sleep maintained something like a 20 percent reduction.

“What we think is happening is that the new memory, which is very weak, is stored in the hippocampus,” Hu said. “But when it’s activated by this sound cue, perhaps it’s reorganized into the neocortex, where memories are more stable and longer lasting.”