People remember moments immediately after a distressing episode with more clarity than the moment preceding the distressing event.

Research investigating memory and trauma published in Cognition and Emotion could help inform the approach to treating PTSD, assist clinicians in combating memory loss in Alzheimer’s and even improve evaluation of eyewitness testimonies.

“We know that we overall tend to have better memory for emotional events, but not all aspects are equally remembered. Sometimes, memory for contextual details surrounding emotional events is impaired. The same goes for memory for temporal aspects, or the order of events preceding or following emotional events – in some cases, it’s enhanced, whereas in others is impaired. So, we wanted to understand why this is the case,” Florin Dolcos, co-author of the study and a professor of psychology at the University of Illinois Urbana-Champaign told Theravive.

“In the article, we talk about PSTD (characterized by involuntary retrieval of distressing memories), but the impact of emotion on memory goes beyond that. A symptom of depression is rumination: continuously dwelling on negative thoughts and often about personal negative memories. A symptom of anxiety is catastrophizing: assuming that terrible things will happen in the future, often because they have happened in the past. So, understanding how emotion impacts different aspects of our memories in healthy functioning is key to understanding mechanisms of memory distortions in different clinical conditions.”

Florin and Sanda Dolcos have been examining the relationship between memory and mental health for over 15 years.

As part of this study with lead study author Paul Bogdan, the researchers conducted two experiments.

One experiment involved 72 participants viewing a series of images that simulated memories. Half of the images elicited a negative emotional response from the participants, and half were emotionally neutral.

The participants were asked to imagine that they were travelling in the locations seen in the pictures. This was to contextualize the images and make them seem more like memories. They were also asked to make up a story that joined all of the images together.

An hour later, they viewed sets of images in a pair. They were asked whether the second pictures occurred immediately before or after the first pictures, or whether neither option was applicable.

The researchers found that the participants were able to more accurately place the second image if the negative memories from the images happened before the neutral ones.

If the participants saw a negative image first, they were able to better remember the neutral images that followed.

This suggests that memory can flow from the negative to the neutral.

“People have better memory for neutral details about what came after an emotional event compared to what came before it,” Bogdan said.

But studying memory is not without its challenges.

“In the lab, researchers typically try to simulate emotional experiences with negative images, loud sounds, or mild electric shocks. These elicit emotional responses and can shed light on mental illnesses. For instance, studies that have induced stress via these types of techniques have found similarities to the stress associated with anxiety,” Bogdan said.

“However, we are under no illusion that these types of procedures capture the full complexity or weight of mental illnesses. Hence, it is also important to investigate similar issues in clinical groups, which sometimes is a challenge because access to clinical participants is more difficult.”

The researchers argue having an understanding of how people experience memory around negative events could be as helpful in the clinic as in the courtroom.

“Knowing this can inform us to try and focus on recollecting as many details happening before something negative happened, so that we can establish possible causal links leading to that negative event. This is important, for instance, in our social lives, such as when we try to avoid situations leading to arguments, or in legal circumstances, when we may need to testify as witnesses of negative incidents. In both cases, emotion’s impact on reasoning may be linked to its impact on memory,” Dolcos said.

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