MENTAL HEALTH
Don’t look back: The aftermath of a distressing event is more memorable than the lead-up, study suggests
The moments that follow a distressing episode are more memorable than the moments leading up to it.
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BECKMAN INSTITUTE FOR ADVANCED SCIENCE AND TECHNOLOGY
IMAGE:
PAUL BOGDAN (LEFT) AND SANDA AND FLORIN DOLCOS.
view moreCREDIT: PHOTO BY L. BRIAN STAUFFER.
Halfway through a true crime podcast, a morning commuter jerks the wheel to narrowly avoid a collision. When discussing the podcast with a coworker later that day, the driver can easily recall the details of the episode’s second half but retains only a blurry recollection of how it began.
A new study from psychologists at the Beckman Institute for Advanced Science and Technology suggests that we remember the moments immediately following a distressing episode more sharply than the moments leading up to it. Clarifying the relationship between trauma and memory can improve how we evaluate eyewitness testimonies, inform therapies to treat PTSD, and help clinicians combat memory decline in brain disorders like Alzheimer’s disease.
This study appears in the journal Cognition and Emotion.
“It’s a clean finding, and it opens up an entirely new dimension for understanding emotion’s impacts on memory,” said lead author Paul Bogdan, whose Ph.D. research at the University of Illinois Urbana-Champaign formed the basis for this study.
Bogdan’s research was conducted within the Dolcos Lab headed by psychology professors Florin Dolcos and Sanda Dolcos. For more than 15 years, the Dolcoses have studied the relationship between mental health and memory — specifically, unwanted memories that intrude into our daily lives, degrading mental health and aggravating anxiety, depression, and PTSD. The result of their research is an emotional security system, crafted with cognitive therapies that protect emotional security and preserve focus in the face of troublesome recollections.
Studying traumatic memories is tricky, the researchers say, because our brains tend to auto-edit negative experiences. Big ideas trump details, peripheral features concede to central ones, and specific moments are cut loose from their context: the where, when, and “what else,” Florin Dolcos said.
So far, there is little evidence to explain how negative emotion impacts the when: our ability to situate a sequence of memories along a timeline.
“Suppose your partner unexpectedly insults you in the middle of an otherwise neutral discussion. Later, when you are trying to make sense of the encounter …, will you more accurately remember what happened before or after the insult?” Bogdan said. “Existing research does not give us a clear answer.”
But Bogdan’s new research might. His team orchestrated two identical experiments: an initial study of 72 participants to pin down their procedures and predictions, and a replication study with 150 participants to confirm the results.
First, participants viewed a series of images simulating a string of memories. Half of the images elicited negative emotional responses, and half were emotionally neutral. To contextualize the images — and make them more memory-like — the participants were asked to privately imagine themselves traveling among the locations pictured and to craft a creative story arc to bind them together. This “promoted the feeling that pairs of sequential images are meaningfully related,” the researchers wrote.
An hour later, participants viewed pairs of images from the series. For each pair, they were asked whether the second picture occurred immediately before or immediately after the first. (They were also offered a “neither” option and could indicate if they did not remember the order.)
Results were consistent across both studies. The participants’ ability to accurately place the second image improved when the negative memories occurred before the neutral ones on the timeline. If participants were shown a negative image first, they did a better job of recalling neutral images that followed it; inversely, if participants were first shown a neutral image, they could more consistently place the negative images that came before.
In other words, memory flows from negative to neutral.
“So, our results suggest that if insulted in a conversation, one would better retrieve what was said immediately afterward than what was said immediately beforehand,” Bogdan said.
This is unintuitive, the researchers say.
“You might imagine that humans evolved to have a good memory for what led to negative things,” Bogdan said. “If you got bit by a snake, what foolhardy thing were you doing beforehand?”
One explanation is that negative emotional spikes (for example, upon sustaining a snake bite) cause a rush of focus and alertness, telling our brains to take exhaustive notes about what happens next and squirrel them away for future use.
But the prelude to trauma employs a much less diligent notetaker. This casts a dubious eye on scenarios like witness testimonies, where contextual details are paramount.
“Knowing that people are more likely to miss details leading to something negative that happened, we can be more cautious about statements related to events that have led to a crime, compared to memories of what happened after, which we know will be sharper,” Florin Dolcos said.
As relevant in a clinic as it is in a courtroom, these results help clarify the mechanisms behind PTSD, where an objectively neutral activity can trigger an involuntary surge of negative emotions.
“For example, a war veteran hearing a loud noise and inferring that their building will soon collapse due to an explosion,” Florin Dolcos said. “This happens because there is a rupture between the memory of the traumatic experience and its original context: the what breaks from the where and the when.”
Taking back control over traumatic memories, then, requires reattaching them to their context — their original place and time. The researchers hope to incorporate this strategy into cognitive therapies for people with PTSD.
In addition to muting the maelstrom of negative memories, another therapeutic avenue may entail using positive emotions to reconstruct sturdier, sharper memories for those who need them, according to Sanda Dolcos.
“As people age, problems with memories become more serious, especially conditions like Alzheimer’s,” she said. “The memory for context suffers the most. If we know exactly what’s happening, we can build future strategies to better encode information that will help us help others with those conditions.”
Editor’s note
The paper titled “Emotional dissociations in temporal associations: opposing effects of arousal on memory for details surrounding unpleasant events” is available online here: https://doi.org/10.1080/02699931.2023.2270196
For full author information, please consult the publication.
Bogdan recently defended his Ph.D. thesis and will soon begin a postdoctoral research position at Duke University. Florin Dolcos is also a professor of biomedical and translational sciences, and both Florin and Sanda Dolcos are affiliates of the Center for Social and Behavioral Science.
JOURNAL
Cognition & Emotion
SUBJECT OF RESEARCH
People
ARTICLE TITLE
Emotional dissociations in temporal associations: opposing effects of arousal on memory for details surrounding unpleasant events
Repeated sexual failures cause social stress in fruit flies
Rejected males experience frustration that impairs their ability to cope with other stresses
Repeated failures to reproduce make fruit flies stressed and frustrated, which in turn makes them less resilient to other types of stress, Julia Ryvkin at Bar-Ilan University and colleagues report in the open-access journal PLOS Genetics, publishing January 18.
Animals are motivated to take actions that improve their survival and reproduction through reward systems in the brain, but failure causes stress. The reward systems have been extensively studied, but less attention has been paid to how animals respond to failure. To investigate, researchers compared the behaviour of male fruit flies (Drosophila melanogaster) that had experienced repeated sexual rejection, with males that had recently mated and naïve males that had been kept in isolation. They found that rejected males were more active, more aggressive, and less social towards other males — indicating a frustration-like state of stress. Rejected males were also less resilient to two other types of stress: starvation and exposure to a toxic herbicide that causes oxidative damage. To understand how this stress response is controlled in the brain, the researchers manipulated the signaling system of neuropeptide F, which is involved in reward processing and aggression. Inhibiting neuropeptide F receptors made flies less resilient against starvation, mimicking the effects of repeated sexual rejection. Using a technique called optogenetics, which uses light to stimulate activity in specific cells, the team activated neuropeptide F receptor neurons and found that this also reduced the flies’ ability to withstand starvation.
These results show for the first time that fruit flies experience social stress when their attempts to mate repeatedly fail. The response is mediated by a brain signaling system involving neuropeptide F, which also plays a role in reward- and stress-responses in other organisms. This offers an opportunity to further investigate social stress in a model organism with a simple nervous system, the authors say.
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In your coverage, please use this URL to provide access to the freely available article in PLOS Genetics:
http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1011054
Citation: Ryvkin J, Omesi L, Kim Y-K, Levi M, Pozeilov H, Barak-Buchris L, et al. (2024) Failure to mate enhances investment in behaviors that may promote mating reward and impairs the ability to cope with stressors via a subpopulation of Neuropeptide F receptor neurons. PLoS Genet 20(1): e1011054. https://doi.org/10.1371/journal.pgen.1011054
Author Countries: Israel, US
Funding: This work was supported by the Israel Science Foundation Grants (384/14 and 174/19 to GSO). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
JOURNAL
PLoS Genetics
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Animals
ARTICLE PUBLICATION DATE
18-Jan-2024
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