Reduce Your Prejudices While You Sleep

By Xiaoqing Hu, University of Texas at Austin | May 28, 2015 1:33 pm


Your brain does a lot when you are asleep. It’s when you consolidate memories, and integrate the things you’ve learned during the day into your existing knowledge structure. We now have lots of evidence that while you are sleeping, specific memories can be reactivated and thus strengthened.

We wondered whether sleep could play a role in undoing implicit social biases. These are the learned negative associations we make through repeat exposure – things like stereotypes about women not being good at science or biases against black people. Research has shown that training can help people learn to counter biases, lessening our knee-jerk prejudices, many of which can operate without our notice.

We know from earlier studies that sound can cue the process of memory consolidation. Can this sleep-based memory trick strengthen newly learned information and in turn help reduce or reverse biases?

Sleep Strengthens Memories

The mechanism that strengthens and stabilizes memories of new information while you sleep is replay. When you learn something, the neurons in your brain start firing to make new connections with each other. Once you hit the sack, those neurons fire again in a similar pattern to when you were awake and learning.

This replay takes memories that are still fresh and malleable and makes them more stable and long-lasting. Some memories can be spontaneously reactivated during sleep; but recent studies have shown that we can directly manipulate which memory gets reactivated and consolidated using sound cues. This is called targeted memory reactivation.

To do this researchers have paired unique sound cues with learning episodes, so that there are strong associations between the sound cues and the information learned. Imagine a certain beep being played every time a subject is shown picture of a face associated with a certain word. After people fall into deep sleep we can reactivate these memories by replaying those specific beep sound cues. Because the sleeping brain still processes environmental stimuli, such sound cues serve to remind the brain of these memories – and help them become stable and long-lasting.

Prior studies already showed that we can selectively improve memory for the location of objects (like remembering where objects appeared on a computer screen) or skills (like playing a melody).

Social biases are learned – like bad habits. We know that habits are well-learned, and can operate without effort, even without our awareness of their influence. Many daily routines are habits: we don’t need to reflect upon them or think twice. Rather, we do these routines automatically. Learning to counter preexisting biases is like learning a new habit, and at the same time, breaking an old, bad habit.

Prior research on prejudice and stereotyping shows that extensive counter-bias training can lessen automatic stereotyping. Building on this bias reduction and sleep-based memory consolidation research, we aimed to test whether people can further process such counter-bias memories during sleep. Can such learning reduce long-lasting stereotypes and social biases?

The IAT test.

The IAT test.

Unlearning Bias

We recruited 40 participants from Northwestern University. They were all white and 18-30 years old. We started by measuring their baseline implicit social biases using an implicit association test (IAT) (which you can take yourself).

An IAT can test the associative strength between a concept and a stereotype, for instance “female” and “math/science.” It measures how fast the subject presses a button to make associations. The longer it takes someone to connect a female face with physics, for instance, the stronger their bias against women and science. Everyone took two versions of the test – one that looked at gender bias and another that looked at racial bias. We ended up with a quantification of each subject’s implicit biases.

We then had participants go through counter-stereotype training, which is meant to help reduce preexisting stereotypes. We targeted gender stereotypes (e.g., women are not good at science) and racial bias (e.g., black people are disliked). Participants were shown pictures of faces paired with words that countered a specific stereotype. Specifically, we showed female faces with words associated with math or science, and black faces paired with pleasant words like cheer, smile, honor.

During the session we also played sound cues that became associated with these pairs. Whenever the participant made a fast and correct response to counter-bias stimuli pairs – for instance, associating female faces with science words or black faces good words – they heard a particular sound cue. One sound was for gender biases, another for racial biases.

After the counter-stereotype training, participants took a 90-minute nap. Once they entered deep sleep, we played one of the two sounds cues repeatedly without waking them up. Since participants were exposed to both sounds during counter-bias training, but just one during their nap, we were able to draw comparisons between the one cued while they slept and the one that was not. That meant we could compare how much the stereotypes targeted by the training were reduced.

Reduce Stereotypes In Your Sleep

After the nap, we tested whether subjects had reduced their level of bias, by having them re-take the implicit association test. Pre-existing stereotypes that were associated with the sound cue replayed during sleep were significantly reduced when the participant woke up. So if a participant heard the sound cue associated with the counter gender-bias training while they slept, when they re-took the IAT they were less likely to use stereotypes about women not being good at science.

We were surprised that this sleep-based intervention was so powerful when participants woke up: the biases were reduced by at least 50% relative to the pre-sleep bias level. But we were also surprised at how long the effect lasted. At the one-week follow up test the sleep-based intervention was still effective: bias reduction was stabilized and was significantly smaller (approximately 20%) than its baseline level established at the beginning of the experiment.

This is unexpected because a one-time intervention can quickly decay when people return to their normal life. But those during-sleep sound cues helped subjects retain the counter-stereotype training effects. Our finding agrees with the theory that sleep is important for the long-term stabilization of memories.

A Path Toward Change

Our society values egalitarianism, yet people may still be influenced by racial or gender biases. Even the best-intentioned of us have preexisting biases but that doesn’t mean we can’t change. Here we show that biases can be changed and that the lasting effect of our counter-stereotyping intervention depended on replay during sleep.

We might be able to use this method to reduce other preexisting, yet undesired, thoughts and beliefs. Beyond gender and racial stereotypes, these methods could be used to reduce other biases, such as stigma toward disability, weight, sexuality, religion or political preference.

Because we designed this study thinking of biases as a type of bad habit, it may also have implications for how to break other bad habits, such as smoking.

The Conversation

This article was originally published on The Conversation.

Image by MJTH / Shutterstock

CATEGORIZED UNDER: Mind & Brain, top posts
  • OWilson

    Sounds like something from the Gulag, or the Third Reich. How long before it is tested in a school near you?

    Mother Nature genetically imprinted us with biases, and armed us to be discriminating (in the true sense of the word). It is society’s personal traffic light.

    Who is going to play God and define “bias”, liberals? socialists? The Tea Party?

    I can see why it would be attractive to liberal academics. All those Global Warming Deniers (criminals and traitors to the planet, as they have been called) to re-educate.

    By the way, let’s at least call it by it’s politically incorrect name: brainwashing!

  • Enopoletus Harding

    1. Replication needed!
    2. Assuming this works (which I doubt), this is no doubt an unethical form of brainwashing.

  • Mister_Carson

    stereotyping no doubt evolved as a safety device. Get bitten by an eight legged hairy thing? Avoid ALL eight legged hairy things.

  • NothingMan00

    Could you use your nocturnal brainwashing techniques to train negroes to stop raping and murdering and reproducing? That would be a much better application of this Orwellian tech.

    • codemonkey

      It’s called “fathers”. pre-welfare and pre-feminist courts, the negros actually had those things. Then the leftists came and figured out a way to reenslave those idiots.

  • advancedatheist

    Yeah, tell women that they need this technology to reduce their prejudices about registered sex offenders who want to move into their neighborhoods.

  • LegallySpeaking

    lol. just lol.

  • codemonkey

    Mind control. You can use the exact same techniques to teach people to be biased against others. That the author doesn’t for a moment bother warning the readers of this, instead gushes endlessly about how this will save the planet, demonstrates that his intention is to manipulate the public.

  • James Thompson

    40 persons is too small a number to draw any conclusion about humanity. This is primarily a word association learning task. Need proper effect sizes before coming to any judgement. The idea that noticing any pattern constitutes “bias” is laughable.

  • Travis

    Jesus, this is creepy. Brave New World, anyone?

    “We’ll just brainwash all those politically incorrect thoughts right out of you and your children! Only right-think from now on!”

  • Willie

    N=40. LMAO.Why does Science keep publishing stuff like this?

    • OWilson

      Today, science is to Newton, what Lady Gaga and Puff Daddy are to Mozart and Beethoven.

      Or, monkey finger painting to Rembrandt and Michelangelo.
      Or the Clinton’s to Winston Churchill.
      Or the Simpsons to Casablanca.

      A little coarsening of the culture, is all.

  • Allen Joseph

    we can’t no longer holdout on our old believe anymore on anything

    • OWilson


      THAT”S what they would have you believe. Then they can start over in their own brave new “progressive” image.

      You CAN improve the gene pool!

      Just don’t be go over the cliff with the rest of the lemmings.

      Dare I say, here, be skeptical?

  • Uncle Al

    Social biases are learned – like bad habits” Social bias activates when resources cannot support populations. When somebody imicturates upstream of your drinking water, kill them.

    “Humanitarian” food awarded Arabia huge young male populations unsupportable by local economics. 1000+ years of European overpopulation used recursive infantry engagements to slaughter young males (Arabian ~30 million KIA required). Suicide bombing is an insufficient increment.

    The US softened unbridled breeding with big cities, production by low IQ labor, and consumerist consumption velocity of money. The US now has Welfare plus service industry low IQ labor that produce bother. US consumption is saturated. Federal Reserve $trillion/year “creation” of zero-interest obligations is hard by detonation, to be followed by “civil unrest” (socially biased wholesale slaughter).

  • Fraga123

    RightThink is for everyone.

  • inconvenientroof

    “Our society values egalitarianism”

    Because its been brainwashed to.

    Man, the Progs already have complete control over the major news media, education, entertainment, government and most religions. Now they want to program us in our sleep because there’s still a few people who look at the world as it really is.

  • Harland

    “Our society values egalitarianism” ?!??

    Which society is this‽ The racist, sexist, literally-worse-than-Hitler USA? Srsly?

    Your different wings of propaganda have got to get together and hammer out these sorts of things ahead of time. America cannot simultaneously be a shining city on a hill of egalitarianism and the worst functioning fascist theocratic corporate oligarchy in the world. You’d have to be able to simultaneously accept two mutually contradictory beliefs as correct in order for this to be valid, and I don’t believe that pro-diversity activists are capable of this kind of mental regressiveness.

    • OWilson

      Never accuse progressives of consistency.

      They have a rainbow coalition, a diverse big tent.

      (As long as you agree with their weird logic, Man Made Global Warming and vote for their criminal leaders. Bill and Hill)


    • AnnPelham

      They believe their own propaganda.

  • Mike Richardson

    While I can understand the concern over possible unethical uses of this technology, it’s amazing to see there are actually posters here who seem more concerned about losing their obvious prejudices. Well, you can cure ignorance with knowledge, but willful and proud ignorance (aka stupidity) is a different story. As the saying goes, you can’t fix stupid.
    But to echo some of the other posts, this study does need a larger sample size, and any such application would need to be very transparent to avoid any coercion or exploitation of unwilling subjects. It definitely warrants scrutiny and serious ethical review before it could be considered as a possible therapy for those interested in overcoming unwanted negative attitudes.

    • OWilson

      I’m sure with a little oversight, by government agencies, to ensure it is not misused, it will one day be “considered a possible therapy”.

      I’m all for trying this on the terrorists in Gitmo, but somehow I sense this is more subtly aimed at the domestic population who as the poster above notes are “posters here who seem more concerned about losing their obvious prejudices, curing “ignorance with knowledge”, and “willful and proud ignorance (aka stupidity)”

      Perhaps with just a little therapy, I could be cured of my unwanted negative attitudes towards stupid and arrogant left wing radicals.

      But first, you need to build on the main body of scientific groundwork of the multinational scientists who worked on this issue in the past.

      1942 to 1945, in Germany I believe it was, 1950 to 1953 in Korea, and from 1916 to about 1985 in the USSR.

      • Mike Richardson

        See, you do reply to some of my original posts. And what a vigorous response! But bear in mind I’m only serving as the devil’s advocate here, putting it out there that if this is to be studied, better in an academic setting transparent to the public and open to peer review — unless you’d rather it be carried out in secret by “da gubmint.” But I was actually aiming my comments more at the initial poster and the bobbleheads that seemed to think his racist remarks were a clever contribution to the discussion. I can’t imagine you’d have a problem with that characterization. And you didn’t fail to invoke Godwin’s Law before closing, either. I mean, university campuses = Dr. Mengele? Really? But a correction on your dates — the Soviet Union didn’t exist in 1916. The Bolsheviks didn’t come to power in Russia until the October 1917 (well, November on our calendar) revolution, and the Soviet Union was established in 1922. But why let facts get in the way of a good argument, right?
        “Perhaps with a little therapy, I could be cured of ‘my unwanted negative attitudes'” — well, that’s between you and your health care providers, but you haven’t responded well to other people’s suggestions that you have therapy in the past. Although, to be fair, I don’t think all of them had your best interests at heart (particularly the ones suggesting a less-than-voluntary treatment regimen — now that’s not terribly nice!). But at least admitting you might want to change is a good start.
        Well, anyway, you should probably get a good night’s rest. Just think those pleasant thoughts as you drift off, and maybe hum Depeche Mode’s “People Are People.” Pleasant dreams, Wilson. 😉

        • OWilson

          Ah, there you are.

          Let’s just say I rarely respond to your original posts which are mostly banal, bland, me too stuff, agreeing with the article’s author.

          But if the right bait is dangled in front of you, the aggresive radical side of your socialist ego will erupt, and I enjoy that.

          Like all good lefties, you have the ability to shift from the larger point, by parsing grammar, typos, spelling, actual dates, anything in fact to avoid addressing the main point of an argument.

          But you are not quite in the league with Lanny Davies, Paul Begala, James Carrville, and their dear leader Bill Clinton who could answer a straight question, with a rambling definition of what “is” is, or to successfully claim he was never “alone” with Monika, or Paula, because other people were actually in the building at the time.

          Now THAT is deflecting at it’s very best!
          You’re not quite there yet. Keep trying. Practice makes perfect!

          • Mike Richardson

            So the facts aren’t important to you? Must be a concern only to us silly leftists. Got it. To the point. Good evening, my man. Oh, and good health. :)

          • OWilson

            Well, there are facts, then knowledge, then understanding, and then wisdom, then the common sense to comprehend the difference.

            You seem to be stuck at level 1 :)

          • Mike Richardson

            So someone who lacks the facts, for instance, would be a 0, then? Just wondering where you rank yourself on the scale, as it’s become apparent that advancing age does not always bring accumulated wisdom. But as an eternal optimist, I always hold out hope that people can learn, just as through certain measures, they might, for instance, reduce certain prejudices. Well, I bid you good luck at accumulating that wisdom and working your way towards #1. 😉

          • OWilson

            On the contrary, I trust my prejudices against self described “silly leftists” will continue to grow and flourish. :)

    • AnnPelham

      “posters here who seem more concerned about losing their obvious prejudices”

      I’d be interested in evidence for that, not just your projection or strawmanning.

      How about this: I’ll get rid of your prejudices, but it’ll involve LSD, sleep deprivation, and waterboarding? What? You want to keep your prejudices now? You horrible bigot.

      • Mike Richardson

        You must have missed the first post (since deleted – below Wilson’s first post) and response, then, because I think they made their views pretty clear without need for projection. I’ve no idea what your views are, so unless you find yourself making clearly racist statements all the time, my comment probably wasn’t aimed at you. I think the methods discussed in the article also made clear that they weren’t torturing folks or changing their minds against their will, so comparing it to the methods you discussed would be more along the lines of the strawman argument. Hope that clears things up. Have a nice day. :)

  • Alex Swann

    You can get an insight of the patterns developed by constant bomabardment of some thoughts or words into a human mind, 40 human minds to be precise. It is a notoriously small number to derive something out of this study.

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  • AnnPelham

    I always wondered when Nazi and Soviet era science and approaches would re-appear. It also has an MKUltra feel, too…

    In all seriousness, this is ^@!#ing creepy. If people wonder what happens when Leftists get into power, just hand them a copy of Orwell’s leftist manual.

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