There's a Reason Why Stressful Memories Stick Out in Our Minds

Why is it that we can hardly remember what we had for breakfast, but we can’t forget stressful moments in our lives? Recent research may have just uncovered the key reason why.

In a study published this month in the journal Current Biology, a team of researchers from Germany put people through a stressful job interview simulation, then analyzed their brain activity when they recalled aspects of the event. The results showed that people’s brains formed closely linked memories of objects in stressful scenarios, potentially making them more distinct in the mind.

Let’s take a closer look at the research on stressful memories, along with tips on how to feel less triggered by them.

The Study

For the study, researchers from Ruhr-University Bochum recruited 64 people to participate in a mock job interview in front of a two hiring managers. About half the group (33 participants) experienced a stressful version of the simulation, in which the interviewers were neutral and reserved. The others participated in a friendlier job interview with encouraging hiring managers and the freedom to share their aspirations and hobbies.

Throughout the interviews, the participants were exposed to 24 objects (like a soda can, a bag of cough drops, a teapot, and a stapler). The interviewers used about half of the objects in front of each participant.

The next day, the participants underwent functional magnetic resonance imaging (fMRI) scans and memory tests related to the objects from the previous day. The results showed that those who participated in the stressful interview had a stronger memory of the objects than those in the friendly interview group. 

The researchers also found that memory traces of objects used in the stressful interview were more closely linked than those of objects that hadn’t been used. Since brain scans of participants from the friendly interview group did not have this result, it suggests that the brain may set stressful memories apart from other experiences. 

“Stressful memories tend to be stronger than neutral memories because more areas of the brain are getting activated. This study showed that stressful situations recalled later activated both the hippocampus and the amygdala,” explains Jon Nash, CMHC, a licensed clinical mental health counselor at Thriveworks in Sandy, Utah, who specializes in anxiety and trauma. “Where more connections are present, recall can have more details.”

While the study deepens scientific understanding of the way stressful events imprint themselves on our brains, more research is needed to understand how other factors may affect this phenomenon, says Desreen N. Dudley, PsyD, a mental health quality consultant and clinical psychologist at Teladoc.

“While we all may certainly show a tendency to recall more emotional and traumatic memories more readily than those which are more neutral, I believe there are important factors which influence the extent to which such emotional memories persist in one’s mind and negatively impact one’s life,” she says.

Dr. Dudley continues: “For example, other research has found memories which elicited positive emotions are longer-lasting compared to those which elicit negative emotions, with memories that triggered negative emotions fading over time, except in individuals who reported experiencing depression.”

Why Stressful Memories Stand Out

Experts say there may be other reasons why stressful memories can feel so strong, beyond the findings of this study. One potential explanation may have to do with our brain’s primary fear responses, which can be triggered by stressful events.

“In these responses, we get different hormones released into our bloodstream to prepare to respond to the situations presented. Adrenaline is one of these hormones that increase our level of awareness. With heightened awareness, it is not surprising that more details could be recalled,” explains Nash.

Another reason stressful memories can feel more vivid is because those challenging situations teach us important lessons that can serve us in the future, says Dr. Dudley.

“This may be in the form of a mistake made, a relationship lost, a risky decision, or being exposed to a threat of emotional or physical harm which triggered the brain’s autonomic nervous system protective response of fight, flight, or freeze,” she says. “The stressful memories tend to linger for the purposes of people being more alert to recognizing signs of a similar situation, which may lead to the same negative feelings, so that they are more adept at avoiding it.”

Managing the Impact of Negative Memories

Certain mental health conditions, such as depression, anxiety, and post-traumatic stress disorder (PTSD), can cause people to relive stressful memories over and over again. But even people without diagnosed conditions can dwell on things they’d prefer to forget, like an argument with a loved one or a job interview gone wrong. How can we temper the effect of negative memories on our emotional wellbeing?

“A lot of research shows that stressful memories that have problematic results, such as intrusive levels of recall or bringing up distressing levels of emotions upon recall, happen because the memory is left feeling unresolved. Therapy can help to create the necessary resolutions and have a lasting result on the emotional response,” says Nash. 

You can also use techniques to work through stressful memories on your own. Dr. Dudley suggests journaling about the memory, challenging your beliefs or thoughts about that memory, and creating a plan of action for when you’re exposed to triggers of that memory.

“Remind yourself that it is just a memory, something that has already happened, and a memory can’t hurt you,” she says.