Bernstein member involved: Lars Schwabe

Here’s a practical example: If a friend shows you her new blue scooter and you later see it parked in front of the library, your brain automatically combines the existing information with the new information to conclude that your friend might be in the library. In psychological research, these flexible conclusions—which go beyond direct observations—are called inferences.

The current study, conducted by researchers at the University of Hamburg, the University of Texas (USA), and the Radboud University Medical Center in Nijmegen (Netherlands), focused on the effects of stress on these processes—particularly on the reactivation of familiar information.

“It is well known that stress can influence the storage and retrieval of information. We examined for the first time how this state alters the integration of related information and were able to show in our study that existing memories are less likely to be reactivated during overlapping experiences under stress, so that they tend to be differentiated from one another rather than integrated,” explains study leader Prof. Dr. Lars Schwabe, Professor of Cognitive Psychology at the Faculty of Psychology and Human Movement Science.

As part of the study, adult participants had to memorize various pairs of images (A+B) on the first day. The next day, they learned other pairs of images that overlapped with the content from the first day (B+C). Later, the researchers tested whether the participants could make the connection from A to C. To observe differences in how the information from the second pair of images was integrated, one group was deliberately put under stress at the start of the second day through a simulated job interview and difficult math problems. The other group, in contrast, performed only a stress-free control task.

Using functional magnetic resonance imaging (fMRI), the researchers were able to see which areas of the brain were activated during the processing of the individual images. The focus was on the hippocampus, a brain region central to memory processes. It turned out that the stressed test subjects were able to remember the second pairs of images as well as the control group. However, the areas responsible for processing information A were less strongly activated in them when viewing image pair B+C. As a result, they sometimes had more difficulty making the connection from A to C. “Our results thus show that acute stress impairs a central mechanism of memory integration,” said Schwabe.

These findings are significant for various fields. It is known, for example, that various psychiatric disorders such as psychoses or anxiety disorders can impair the ability to draw conclusions. “Impaired integration of overlapping memories is also relevant in a legal context when it leads to false conclusions or unjustified accusations. And in education, the linking of related information is the foundation for long-term learning success,” says cognitive psychologist Schwabe. Therefore, understanding the influence of stress on memory integration is an important starting point for interventions and therapies.