Racial and gender stereotypes can be effectively decreased with a counterbias training which is strengthened by an intervention during sleep. The better the sleep, the better the effect of the intervention!
It is a sad fact that even those people who value tolerance and egalitarianism are not free of prejudice and social stereotypes, for example regarding race and gender. All people suffer to a different extent from unconscious stereotypes, so-called implicit biases. These unconscious beliefs influence our behavior. Many people will for example more likely hire a man than an equally qualified woman for a research assistant.
The fact that these biases are implicit makes them very difficult to change. On top of that, even successful interventions against stereotypes are unlikely to have long-lasting effects for various reasons. One example is the media that often reinforce the stereotypes.
A group of scientists from Northwestern University decided to approach this problem from another perspective. They based their research on the knowledge that our memory can be strengthened during sleep (so-called memory consolidation). The scientists do not know the mechanisms of this effect but think that a repeated reactivation of information in the sleep can help us remember information longer. Therefore, Hu and colleagues asked a group of participants to go through a counterbias training. During this training the participants heard a specific sound when they gave a “socially fair” response. Later, the participants were asked to catch a nap in the lab, and while they were in the slow wave sleep, which is a phase of deep sleep, they heard the same sound. As predicted by the authors, the training was effective in reducing social bias. Furthermore, catching a nap strengthened the observed effect. Finally, the additional intervention during sleep helped to maintain the effects of counterbias training for a week.
Interestingly, the nap had significantly better effect if it was longer and when the quality of sleep was better, meaning that the participants had longer REM and slow wave phases of the sleep during the nap. This finding supports previous theories that the memory consolidation takes place during both phases of the sleep – REM and slow wave.
Authors are cautious in drawing conclusions. More research will be needed to check if the training can have more permanent effects.