Sleep Away Your Bad Attitudes

Generally speaking, you cannot learn from sounds of new information while you sleep, though this was a fad several decades ago. But in an earlier post, I discussed a new line of research where sleep learning can occur. The key is to play sound cues that were associated with learning that occurred during the previous wakefulness period. The explanation I posted was that cue-dependent sleep learning can work because a normal function of sleep is to strengthen memories of new information and that presenting relevant cues during sleep increases the retrieval of these memories and makes them accessible for rehearsal and strengthening.

The latest experiment by a different group shows that this cuing during sleep can modify bad attitudes and habits. The test involved counter stereotype-training of certain biased attitudes during wakefulness, and investigators reactivated that counter-training during sleep by playing a sound cue that had been associated with the wakefulness training.

In the experiment, before a 90-minute nap 40 white males and females were trained to counter their existing gender and racial biases by counter-training. A formal surveyed allowed quantification of each person's level of gender or racial bias before and after counter-training. For example, one bias was that females are not good at math. Subjects were conditioned to have a more favorable attitude about women and math with counter-training that repeatedly associated female faces with science-related words. Similarly, racial bias toward blacks was countered by associating black faces with highly positive words. In each training situation, whenever the subject saw a pairing that was incompatible with their existing bias they pressed a "correct" button, which yielded a confirmatory sound tone that was unique for each bias condition. Subjects were immediately tested for their learning by showing a face (female or black) and the counter-training cue, whereupon they were to drag the appropriate bias-free face on to a screen with the positive word. For example, if the first test screen was that of a woman, accompanied by the sound cue, the subject dragged a woman's face onto a second screen that said "good at math." Results revealed that this conditioning worked: both kinds of bias were reduced immediately after counter-conditioning.

Then during the nap, as soon as EEG signs indicated the presence of deep sleep, the appropriate sound cue was played repeatedly to reactivate the prior learning. When subjects re-took the bias survey a week later, the social bias was reduced in the sound-cued group, but not in the control group that was trained without sound cues.

Experimenters noted that the long-term improvement of bias was associated with rapid-eye-movement (REM) (dream) sleep which often followed the deep sleep during early stages of the nap. That is, the beneficial effect was proportional to the amount of nap time spent in both slow-wave sleep and REM sleep, not either alone. It may be that memories are reactivated by cuing during deep (slow-wave) sleep, but that the actual cell-level storage of memory is provided by REM sleep.

Implications of this approach to enhancing learning and memory show a great deal of promise. Can it be used for enhancing learning in school? Can it be used in rehabilitation of addicts or criminals? But there is a dark side. Now might be a good time to re-read Huxley's Brave New World wherein he actually described conditioning values in young children while they slept. Sleep is a state where people are mentally vulnerable and without conscious control over their thoughts. Malevolent people could impose this kind of conditioning and memory enhancement on others for nefarious purposes.  These techniques may have valid social engineering applications, but they must be guided by ethical considerations.

Dr. Klemm is author of Memory Power 101 (Skyhorse), Better Grades, Less Effort (Benecton), and Mental Biology (Prometheus).

Sources:

Klemm, W. R. (2013). New discoveries on optimizing femory formation.  http://thankyoubrain.blogspot.com/2013/05/new-discoveries-on-optimizing-memory.html

Hu, Xiaoqing et al. (2015. Unlearning implicit social biases during sleep. Science. 348(6238), 1013-1015.

Sleep Learning -- A New Perspective

A couple of decades ago, many people thought you could learn while you sleep. I remember as a college student playing audio tapes of information I wanted to learn while I slept. This idea turned out to be a fraud, perpetrated by people who sold sleep learning materials and equipment. Most "early adopters" found that all it did was disrupt sleep.

But as I have discussed elsewhere, modern research has compellingly shown that the brain is consolidating memories of the day's events during sleep. So, maybe the sleep learning idea is not completely dead. Maybe the right kind of stimulus input while you sleep could promote learning, at least in terms of promoting memory consolidation of the information you already learned during the day.

So, the idea would be to see if sleep can promote memory consolidation of things you recently learned, but have not yet formed into lasting memory. How might you do that? Since memory is largely associative, maybe it would work to provide during sleep the cues that were associated with the original learning. This might have a better chance of working during the dream stage of sleep, because it is well documented that external sound stimuli (like storms, rain, etc.) are documented as capable of becoming incorporated into and changing the course of a dream. Thus, the question becomes: can audio presentation of learned association cues during dreaming promote the memory formation for the original learning items or events. The idea is that the cue might reactivate a latent memory and thus constitute a memory rehearsal.

Partial testing of this idea has recently been reported. Northwestern University scientists trained human subjects to recognize the location of 50 different objects on a computer screen. Each object had an associated sound. For example, the cat image was associated with a meow sound, a kettle with a whistle, etc. Then people took a nap, during which sound cues were presented (unobstrusively at 62 decibels) for half of the images they had previously been exposed to. After the nap, subjects had no conscious recollection of the sound cueing.

The cues were presented oddly enough only during the deep stages of sleep, not during dreaming. Maybe the researchers were unaware that external stimuli can get incorporated into dreams. Even so, the original objects were re-presented after waking and subjects tested for recall of the location of the 50 images.

Measuring the location errors in terms of distance from correct position indicated that accuracy was greater for images that had associative cues presented during the nap than for those images for which cues were not re-presented. Simultaneous recording of brain waves (EEG) showed that the brain was responding to the sensory cues during sleep.

Tests in control subjects, who were tested without the intervening nap, showed that the cues provided no improvement in recall.

The principle seems sound. What remains is for clever entrepreneurs to develop memory-enhancing strategies that are specific for specific learning tasks.

The old ideas of sleep learning are dead, but here is a new opportunity for finding ways to get sleep to work for us. Learning protocols have to be developed for specific learning tasks, and these have to have relevant sound cues. Finally, I suspect that such external learning "reminders" will be more effective when presented during dream sleep, not the deep stage of sleep in which people "fall into a pit" of oblivion. The challenge is to find ways to provide appropriate reminders while we sleep (or dream).

Source: Rudoy, J. D. et al. 2009. Strengthening individual memories by reactivating them during sleep. Science. 326: 1079.