Scientists sheds light on how our brains create mental “chapters” with new event segmentation study

A new study published in modern biology Reveals how the brain divides the continuous flow of information in daily life into discrete, meaningful events. The findings suggest that these disagreements – similar to starting a new chapter in a book – are not just caused by changes in the environment around us. Instead, they may be influenced by internal scripts based on past experiences and current goals. This active segmentation process reflects how the brain prioritizes information to accommodate what is most important to us at any given moment.

Scientists have long been interested in how we process the constant stream of events in our daily lives and understand them as distinct moments. This segmentation process is critical for understanding the world, updating mental models, and forming lasting memories. But what prompts the brain to mark the line between one event and the next?

One possibility is that a physical change in the environment, such as moving from an outdoor space into a building, signals the beginning of a new “chapter.” Another hypothesis suggests that these boundaries are shaped by internal “scripts” – mental templates developed through experience. These scripts allow the brain to filter and prioritize information based on what aligns with current goals. For example, when dining at a restaurant, an experienced diner may pay attention to events such as ordering and its arrival, while ignoring other contextual changes.

The researchers sought to test whether the brain actively constructs these boundaries by prioritizing internal scripts over environmental cues.

“We wanted to understand how the brain processes real-life situations and complex events that unfold over a matter of minutes,” said study author Chris Baldassano, an associate professor of psychology at Columbia University and director of the research center. Dynamic Perception and Memory Laboratory.

“Recent work from my lab and others has found that during typical neuroscience studies, certain parts of the brain, including a group of regions called the default mode network, or DMN, are typically shut down. We’d flash irrelevant pictures or text in there. We wanted to understand what information the DMN (especially the medial prefrontal cortex) was tracking about the narrative, and whether the story would be processed differently depending on what you were currently focusing on.

To explore this, the researchers designed 16 audio narratives, each combining two overlapping “scripts.” One script was location-based (e.g., a restaurant, airport, grocery store, or lecture theater), whereas the other script focused on social interactions (e.g., a breakup, a proposal, a business transaction, or a casual romantic encounter). Each story develops through four different events for each script, which intertwine so that the boundaries of one script are inconsistent with those of another. This setting allowed the researchers to test how attention to different scripts affected participants’ perception of event boundaries and corresponding brain activity.

“These stories were created by Alexandra De Soares, a member of my lab who led the study, and each story is a combination of two ‘scripts’ (i.e., common sequences of events). ,” Baldassano explained. “For example, a story might be about a proposal in a restaurant and progress through the various stages of eating in the restaurant (taking a seat, ordering…), with the events of the proposal happening simultaneously (taking out the ringer, proposing, partner’s reaction…) .

The first part of the study was conducted using an fMRI scanner, with 36 participants listening to the narratives while their brain activity was monitored. Before listening to each story, participants “prepared” by asking a series of questions related to one of the scripts, such as location-specific details (e.g., “What does everyone order at the restaurant?”) or society-specific specific details (e.g., “What was the original reason for the breakup?”). This priming encouraged participants to focus on one script rather than another, effectively shaping their mental priorities during the task. While listening to the stories, the researchers measured participants’ brain activity, specifically in areas of the DMN, which are responsible for processing abstract and meaningful information.

In the second part of the study, conducted online, more than 300 participants heard the same narrative. However, instead of listening continuously, they listened to the story sentence by sentence and were asked to decide after each sentence whether it marked the beginning of a new event. As in the fMRI study, participants were either primed to attend to the place script, the social script, or not at all. After listening, participants completed a memory test, answering questions about story details, including the script they were prepared to focus on and another script they were not prepared to focus on.

The findings showed that participants’ segmentation of events and their brain activity patterns were strongly influenced by the scripts they prepared to prioritize. In online experiments, participants who were exposed to location scripts were more likely to recognize new events at moments that corresponded to location-based transitions, such as entering a restaurant or passing through security at an airport. Likewise, participants who received social scripts were more adaptable to changes in social interactions, although this effect was less pronounced than for location-based events.

“I was surprised to find that telling participants to participate in a socially relevant script (such as a proposal) did not have much of an impact on how chapters were created (compared to a baseline condition in which participants only listened to the story, which was not specified),” Barr said Dasano told PsyPost. “Instructing participants to focus on scripts associated with a location (e.g., a restaurant) resulted in larger changes. In retrospect, this makes sense: By default, listeners are more likely to focus on characters and their social interactions, so when we asked It’s when they look at the story from an unusual perspective that we see a huge difference.

Priming also improved memory recall: Participants remembered details associated with primed scripts more accurately than unprimed scripts. This suggests that focusing attention on specific types of information not only shapes perception but also enhances memory encoding.

In functional magnetic resonance imaging studies, brain activity in the DMN, specifically the medial prefrontal cortex, was consistent with boundaries associated with priming scripts. For example, when participants prepared to focus on location details, neural transitions in this area were consistent with location-based event boundaries in the narrative. These findings suggest that the brain proactively establishes event boundaries based on internal priorities rather than passively responding to environmental cues.

“For decades, researchers in cognitive psychology have been interested in how our experiences (which unfold over time) are divided into chapters, a cognitive process known as ‘event segmentation,'” Barda Sano said. “The main new finding of this study is that these chapters don’t just come from the way the story is written. People don’t just listen to the storyteller telling them when new events begin; they also pay attention to the storyteller. The brain is responding to your current state of mind and goals , actively choose when to start a new chapter.

The study’s design provides controlled observation of how internal scripts influence event segmentation, but it has its limitations. The story used closely follows the script without major deviations, but real-life experiences are often unpredictable.

“In this study, the events in the stories matched people’s scripts perfectly: for example, in the restaurant story, people always got the food they ordered,” Baldassano noted. “My lab and others are currently trying to understand what happens when there is a mismatch between your expectations and the actual experience, such as a waiter throwing a glass of water in a guest’s face. What does this say about how these experiences are organized in memory? Influence?

The researchers also analyzed data on how participants’ perspectives during listening affected their memory recall. This ongoing work aims to deepen our understanding of how real-world experiences are divided into distinct events and stored in memory.

“We are still trying to fully understand how brain regions work together to create memories for realistic, familiar events,” Baldassano said. “Specifically, we are interested in how DMN regions like the medial prefrontal cortex and When messages are sent to and from the long-term memory system in the hippocampus, for example, my lab is currently doing research on patients who have electrodes implanted (as part of epilepsy surgery) so that we can. Direct measurement of neural activity in memory systems.

Research, “Top-down attention changes behavioral and neural event boundaries in narratives through overlapping event scripts“The authors are Alexandra De Soares, Tony Kim, Franck Mugisho, Elen Zhu, Allison Lin, Chen Cheng and Christopher Baldassano.