Study shows how stress forces brain to prioritize memories

The brain is the machine that perceives, analyses, sorts, stores and prioritizes our memories. However, not all experiences and perceptions are stored in the same way, and not everything is remembered equally, especially when under pressure or emotional stress. A new research study carried out by researchers at the Universitat Oberta de Catalunya (UOC) has found that negative emotions help cement the central information, details and key aspects of experiences but diminish recollection of the surrounding context and environment.

"We found that, when experiencing an intense negative emotion, rather than simply focusing on the aspect that triggers the greatest emotional response, the brain strategically prioritizes the aspect that is most relevant to the person's immediate goal," said álvaro Pastor, a recent PhD graduate from the UOC's Network and Information Technologies doctoral programme and one of the authors of the study, alongside Pierre Bourdin-Kreitz, a researcher and member of the Faculty of Computer Science, Multimedia and Telecommunications and coordinator of the UOC's VR laboratory, XR-Lab.

"In the face of intense negative emotion, the brain does not blindly focus on what generates the most emotion, but strategically prioritizes what is most relevant"
Simulations and inducing negative emotions

The authors of the study, which was published open access, created a virtual airport simulation in which participants took on different roles as employees at two boarding gates. They were asked to find and identify specific passengers in the crowd by checking both their names and faces. Some participants did this task under high stress for a prolonged period, while others did it in an emotionally neutral state.

As Bourdin-Kreitz explained, "those participants who were in an intensely negative emotional state remembered both passenger names and faces more accurately and for longer. However, as the exact location where each passenger had been found was not vital to the mission, this detail was not stored in their memory."

Dynamic prioritization of memory

According to these experts, members of the Learning, Media and Entertainment research group (GAME), which is attached to the UOC's Interdisciplinary Research Centre on Social and Cultural Transformations (UOC-TRÀNSIC), the brain's activity is one of the most energy-intensive processes in our body. When it is experiencing a strong emotion, it cannot afford to remember everything equally. To address this, it carries out a dynamic prioritization of memory, which channels its resources towards creating a specific memory.

This way, the brain neither enhances nor suppresses the memory as a whole. Instead, it fine-tunes the associative processes that we experience as memories. "Some associative processes work by connecting separate elements, such as a face and a place. Others merge different elements into a single unit, sometimes also including components that would otherwise remain separate, such as a face and a name. When placed under intense stress, the brain tends to favour the latter type," said Pastor, emphasizing that it is the importance of the event, rather than an object's ability to evoke emotion, that determines the outcome of this efficiency calculation.

Bourdin-Kreitz stressed that this prioritization of certain memories in emotionally negative situations is not a cost but a useful adaptation. "When faced with a highly stressful situation, it is entirely normal not to remember certain details of the context. This does not mean that the memory is false or unreliable; it simply reflects the way the brain operates under pressure."

Practical applications of immersive technologies and virtual reality

According to the experts, both virtual reality and immersive technology can elicit emotions in a sustained and multimodal manner. This ability can be used in ways that go far beyond basic research into memory. "Our findings carry the clear and reassuring message that forgetting certain details after a traumatic or stressful experience does not mean that those memories are faulty or fabricated," explained Bourdin-Kreitz.

As a result, the understanding of the workings of episodic memory gained thanks to this study could be particularly useful in a range of fields, such as education, the justice system, healthcare or emergency response.

In the field of education, for example, it could be used to design learning environments that encourage positive emotional engagement rather than high anxiety. In judicial contexts, it could help avoid challenging victims who cannot recall certain events. In the field of healthcare, it could enable traumatic events or situations that trigger phobias or social anxiety to be recreated under a degree of control that could never be achieved in real life. It could also be used to examine how different emotional states influence decision-making, attention and motor performance.

"In general, it can help us understand and improve systems in which making mistakes under pressure can lead to serious consequences, such as in the fields of aviation, healthcare or critical infrastructure management," said Bourdin-Kreitz.

"While valuable knowledge has been gained using the traditional method, this new approach reveals the interaction between emotions and memory in real-life conditions, helping apply the results to real-world needs in ways that are often not possible using the traditional method," concluded the experts in relation to the use of these new technologies.

This project is aligned with the UOC's Ethical and human-centred technologyresearch mission and contributes to UN Sustainable Development Goal (SDG) 9: Industry, Innovation and Infrastructure.