Research Highlights Memory Bias Towards Post-Traumatic Moments

A recent study conducted by psychologists at the Beckman Institute for Advanced Science and Technology suggests that individuals tend to remember the moments immediately following a distressing episode more vividly than the moments leading up to it.

This finding has significant implications for understanding the relationship between trauma and memory and may impact how eyewitness testimonies are evaluated, inform therapies for post-traumatic stress disorder (PTSD), and contribute to combating memory decline in brain disorders like Alzheimer’s disease. The study, published in the journal Cognition and Emotion, sheds light on the complex interplay between emotion and memory. 

Lead author Paul Bogdan, whose Ph.D. research at the University of Illinois Urbana-Champaign formed the basis for the study, describes the findings as a “clean finding” that opens up a new dimension for understanding emotion’s impacts on memory.

The study was conducted within the Dolcos Lab, headed by psychology professors Florin Dolcos and Sanda Dolcos, who have over 15 years of experience studying the relationship between mental health and memory, particularly unwanted memories that contribute to mental health degradation, anxiety, depression, and PTSD. 

Understanding traumatic memories poses a challenge, as the brain tends to auto-edit negative experiences. Significant ideas take precedence over details, peripheral features yield to central ones, and specific moments lose their contextual information, such as the where, when, and “what else,” according to Florin Dolcos. The study aimed to explore how negative emotion impacts individuals’ ability to situate a sequence of memories along a timeline, particularly the moments before and after a distressing event. 

The researchers conducted two identical experiments: an initial study involving 72 participants to establish procedures and predictions, and a replication study with 150 participants to confirm the results.

Participants viewed a series of images simulating a sequence of memories, with half of the images eliciting negative emotional responses and the other half being emotionally neutral. To contextualize the images and make them more memory-like, participants were asked to imagine themselves traveling among the depicted locations and craft a creative story arc to connect them. 

An hour later, participants viewed pairs of images from the series and were asked to determine whether the second picture occurred immediately before or after the first. The results were consistent across both studies, revealing that participants had a better ability to accurately place the second image when negative memories occurred before neutral ones on the timeline. The order in which images were presented influenced participants’ recall accuracy. 

The study’s findings indicate that memory tends to flow from negative to neutral, suggesting that individuals are more likely to remember what happened immediately after a distressing event than what happened immediately beforehand. This result challenges intuition and raises questions about how humans evolved to remember negative events. Bogdan suggests that negative emotional spikes trigger a rush of focus and alertness, prompting the brain to take exhaustive notes about what happens next and store them for future use. 

One potential application of this research is in the evaluation of witness testimonies, where contextual details are crucial. Understanding that people are more likely to miss details leading to a negative event can lead to greater caution in relying on statements related to events that have led to a crime compared to memories of what happened afterward. 

The study’s implications extend beyond the courtroom to clinical applications, particularly in understanding and treating PTSD. The researchers believe that the study’s insights into the mechanisms behind PTSD, where a neutral activity can trigger an involuntary surge of negative emotions, can inform cognitive therapies. Reattaching traumatic memories to their original context – the where and when – may help individuals regain control over these memories and reduce PTSD symptoms. 

The study also suggests potential therapeutic avenues, such as using positive emotions to reconstruct sturdier and sharper memories. For individuals dealing with memory-related issues, especially conditions like Alzheimer’s, understanding the memory for context is crucial.

Building future strategies to better encode information can have a positive impact on helping those with memory-related conditions. The researchers hope to incorporate these strategies into cognitive therapies for individuals with PTSD and explore their application in addressing memory decline associated with aging and neurodegenerative disorders. 

Journal reference  

Paul C. Bogdan et al, Emotional dissociations in temporal associations: opposing effects of arousal on memory for details surrounding unpleasant events, Cognition and Emotion (2023). DOI: 10.1080/02699931.2023.2270196.