Bad experiences can shape our lives in unconscious ways. If you, say, tried a new dish at a restaurant and got food poisoning, you may not only avoid that restaurant in the future but potentially that dish, even in other settings. Researchers have documented in many studies how negative emotions can shape our memories and decision-making. Less known, however, is how those negative events are organized in our memories – which is the subject of a new study in the Journal of Cognitive Neuroscience.
“We wanted to go beyond the well-known pattern of having strong memories for threatening events, to understand how this experience would be organized in our memory,” says Elizabeth Horwath, lead author of the paper and who was part of the Murty Lab at Temple University. Past work has found that positive experiences are organized together based on their positive aspects as opposed to chronologically.
“We were curious as to whether threat memories would be structured in the same way,” Horwath explains. “Thinking back to the restaurant, it is possible that you may remember your experiences at restaurants in the order in which you went to them, or you may group together all negative experiences you’ve had to avoid possible bad dishes in the future.”
The research team found that negative experiences are not grouped together in memories like the positive ones. In addition, a threatening context enhanced memory for all items presented, even if the items were not directly threatening.
I spoke with Horwath about these findings and their implications for memory research, as well as the paper’s place in a special collection in honor of cognitive neuroscientist Sarah DuBrow.
CNS: Why look at threat motivation and memory?
Horwath: Most of my research has focused on the relationship between reward motivation and memory, but of course not all of our experiences in our day to day lives are positive. In reality, we face a diverse range of positive and negative experiences throughout our days and the valence of those events shape how we remember them. Memory is a crucial aspect of our cognition that allows us to move progressively from one day to the next, but since there is such diversity in our experiences, we cannot treat memory as a one size fits all phenomenon. Understanding the structure of threat memories will provide more insight into the overlap between the impact of positive and negative events on memory.
CNS: What new insight were you seeking with this study?
Horwath: Most work at the intersection of threat motivation and memory has focused on characterizing threat’s influence on memory accuracy, e.g., whether or not you remember seeing an item before. But our experiences are highly complex, meaning it could possibly be more adaptive to restructure and transform how memories are stored as opposed to keeping the original event as an exact copy. Our goal here was to understand how threat influences the organization of memory, which we tax by measuring the order in which information is recalled.
CNS: What were you most excited to find? Were any findings surprising?
Horwath: In our previous work, we saw that reward encourages memories to be structured based on the value of information, meaning important items will be grouped together. We actually saw the opposite pattern in this study, where threatening items are less likely to be grouped together, highlighting the differences that threat and reward can have on our memories.
CNS: Was there anything surprising?
Horwath: Two findings were surprising to us. First, it is common to see an enhancement of memory for items associated with a threat, but in this study, we saw an overall state-level enhancement for all items in the threat study, regardless of whether the items were associated with a high or low threat. This is possibly because threat memory is often tested with a recognition test where people are asked if they remember seeing specific items, whereas we used a recall test where people needed to generate items from memory organically.
The second, which our lab has been working to tease apart in several studies, is that previous work has shown that threat distorts temporal memory – meaning that experiencing a threat will lead to recalling the memory in an order different to how it was originally experienced. Yet in this study, threat did not influence the extent to which memories were organized around temporal features.
CNS: Were there any novel techniques in your study that you would like to highlight?
Horwath: We developed an analysis technique in this work and a previous paper addressing similar questions in the context of reward motivation. This method allowed us to look at the grouping of learned items based on value, which we called category clustering. That would look like recalling items of the same value category together (e.g., high threat, high threat, high threat, low threat, low threat, high threat…). This technique took much consideration given the inherent bias that motivation has on increasing memory accuracy in general, but was crucial in helping us answer our questions in this study.
CNS: What do you most want people to understand about this work?
Horwath: Our experiences are highly complex and there is not a 1:1 translation of how they will be remembered. There are many factors that can influence what we will remember long-term and how those memories will be structured. This work has highlighted a large distinction in how threat and reward influence memory organization.
For cognitive neuroscientists, it is important to consider the implications of how reward and threat differently influence hierarchical memory organization. This work contributes to a growing body of research that demonstrates differential engagement of the medial temporal lobe when considering motivation’s influence on episodic memory formation. This presents future questions as to whether differences in memory organization are associated with prioritized engagement of amygdala-perirhinal circuits versus more hippocampal-based circuits.
CNS: What’s next for this line of work?
Horwath: As cognitive neuroscientists, it’s crucial to understand the behavior of phenomena that we’re interested in, but the next step for this work is to connect that to the underlying neural mechanisms. We would be interested in understanding how the brain supports the structure of threat memory and the downstream consequences on our future adaptive behavior and decisions.
Also, previous work has largely been conducted with recognition memory tests. This paper provides a strong reasoning for considering memory organization with a finer tooth comb, for example with recall tests, where we can tap into features important to memory organization.
CNS: Is there anything else I didn’t ask you about that you’d like to add?
Horwath: This paper was written as part of a special issue in memory of Dr. Sarah DuBrow, an esteemed and cherished memory researcher and mentor. I would like to take this opportunity to further recognize the foundation that her work has provided to our understanding of the many aspects of memory organization, her crucial contributions to this work specifically, as well as the value her mentorship provided for my development as a scientist.
-Lisa M.P. Munoz
