Selective forgetting: New discovery could help people forget specific memories

Turns out, scientists "can both increase and decrease the ability to recall specific memories" in humans.
Sade Agard
Woman wearing brainwave scanning headset.
Woman wearing brainwave scanning headset.


Playing sounds to people while they sleep can help them forget tragic memories, revealed a new study published in PsyArXiv.

Researchers at the University of York claim that the early-stage discovery could lead to the development of methods for reducing the effects of traumatic and intrusive memories.

'We can both increase and decrease the ability to recall specific memories'

"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," said Dr. Bardur Joensen in a press release, first author of the study, and a former Ph.D. student at the Department of Psychology, University of York.

"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," Joensen added.

An object word such as 'hammer' was 'quietly' played to people entranced in Stage 3 sleep

Twenty-nine individuals were taught associations between word pairs for the study. They were instructed, for instance, to memorize the word pairings "hammer - office" and "hammer - Cardi B."

The individuals then spent the next night in a sleep lab at the University of York. Participants were quietly played the word that indicated the object in the pair- in this case the hammer- once they entered stage three sleep, also known as deep or slow-wave sleep.

Scientists have been developing 'selective remembering' methods too

According to earlier studies, memorizing a pair of words and listening to a sound connected with that pair while participants slept helped them remember the phrases when they woke up the following day. So in this way, a form of 'selective remembering' could be demonstrated.

Now, researchers provide evidence that the opposite, that is, selective forgetting, is also possible. In this case, they discovered an increase in memory for one pair but a decrease in memory for the other pair when the word pairs overlapped.

'The relationship between sleep and memory is fascinating'

The results seen in the study, in the opinion of the researchers, were significantly influenced by sleep.

Dr. Aidan Horner from the Department of Psychology at the University of York, and lead author of the study, stated: "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."

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"This research raises the possibility that this process could be manipulated so that sleep could be used to help weaken painful memories."

Is this an effect scientists could turn on and off in the future?

"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," revealed Horner.

Overall, while earlier studies indicated that playing 'sound cues' during sleep can boost certain memories, this most recent study offers the first solid proof that the practice can also be utilized to aid in forgetting. Care to be the next participant?


Memory reactivation during sleep can shape new memories into a long-term form. Reactivation of memories can be induced via the delivery of auditory cues during sleep. Although this targeted memory reactivation (TMR) approach can strengthen newly acquired memories, research has tended to focus on single associative memories. It is less clear how TMR affects retention for overlapping associative memories. This is critical, given that repeated retrieval of overlapping associations during wake can lead to forgetting; a phenomenon known as retrieval-induced forgetting (RIF). We asked if a similar pattern of forgetting occurs when TMR is used to cue reactivation of overlapping pair-wise associations during sleep. Participants learnt overlapping pairs; learnt separately, interleaved with other unrelated pairs. During sleep, we cued a subset of overlapping pairs using TMR. While TMR increased retention for the first encoded pairs, memory decreased for the second encoded pairs. This pattern of retention was only present for pairs not tested prior to sleep. The results suggest that TMR can lead to forgetting; an effect similar to RIF during wake. However, this effect did not extend to memories that had been strengthened via retrieval prior to sleep. We therefore provide evidence for a reactivation-induced forgetting effect during sleep.

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