HESLINGTON, United Kingdom — The past often serves to motivate and push us forward, but bad memories also have a way of holding us back. Traumatic, sad, or just downright embarrassing memories tend to persist in our minds and bubble to the surface at inopportune moments. Now, researchers from the University of York suggest there may be a simple way to leave bad times in the past: sound cues.
Scientists report playing sounds to people while they sleep can help them forget specific memories. While this discovery is very much in its early phases, study authors believe their work opens the door for the development of new techniques aimed at weakening traumatic and intrusive memories.
While prior research reveals that playing “sound cues” during sleep can help strengthen or boost specific memories, this is the first ever project to produce compelling evidence that the same strategy can help people forget.
“Although still highly experimental at this stage, the results of our study raise the possibility that we can both increase and decrease the ability to recall specific memories by playing sound cues when an individual is asleep,” says first study author Dr. Bardur Joensen, a former PhD student in York’s Department of Psychology, in a university release.
“People who have experienced trauma can suffer a wide range of distressing symptoms due to their memories of those events. Though still a long way off, our discovery could potentially pave the way to new techniques for weakening those memories that could be used alongside existing therapies.”
How did a sound make people forget memories?
Study authors taught a group of 29 participants associations between overlapping pairs of words. For example, the group had to learn the word pairs “hammer – office” and “hammer – Cardi B.”
Next, participants slept overnight in the University of York’s sleep lab. As they slept, the research team analyzed their brainwaves and then pinpointed when they reached deep or slow-wave sleep (also known as stage-three sleep). When that happened, the team quietly played the word denoting the object for each participant (i.e. hammer).
Earlier studies have found that learning a pair of words and then hearing a sound associated with that pair during sleep can improve participants’ memory for the word pair after waking up the following morning. This project found that when the pairs of words overlapped, an increase in memory occurred for one pair, but a decrease in memory occurred for the other pair. Study authors conclude this indicates it is indeed possible to induce selective forgetting by playing associated sounds during sleep.
“The relationship between sleep and memory is fascinating. We know that sleep is critical for memory processing, and our memories are typically better following a period of sleep. The exact mechanisms at play remain unclear, but during sleep it seems that important connections are strengthened and unimportant ones are discarded,” concludes senior study author Dr. Aidan Horner from the Department of Psychology at the University of York.
“This research raises the possibility that this process could be manipulated so that sleep could be used to help weaken painful memories. The next steps for our research team are to establish how these cues cause forgetting, so that we can turn the effect on and off, and whether we can use the same technique to weaken existing real-world memories.”
The study is published in the journal Learning & Memory.