Psychological trauma associated with enhanced memory control later in life

New research has found that college students who experienced more trauma in early life tend to display a greater ability to control their memories. The study suggests that traumatic events can eventually result in some people being better at regulating intrusive and unwanted memories.

The findings have been published in the Journal of Experimental Psychology: General.

“The incidence of psychological trauma is far more widespread than many realize, with some estimates as high as 80% of the population. Although approximately 7% to 8% of people develop persistent PTSD in the wake of a major trauma, most people recover,” explained study author Justin C. Hulbert, the principal investigator at the Memory Dynamics Lab at Bard College.

“This raises a fundamental question about the nature of this remission: Why do intrusions decline in these individuals? Does this remission reflect a passive forgetting that happens to all memories? Or might people’s early efforts to cope with intrusions help enhance mental functioning to handle new challenges?”

“There’s currently a great deal of interest in determining what makes certain people more resilient than others and how we all might stand to improve our ability to face challenges. In the past, we have shown that most individuals can learn to prevent unwanted memories from coming to mind—at least within the confines of a controlled experiment,” Hulbert told PsyPost.

“However, we have also noted a wide degree of individual differences in their effectiveness at doing so. The current work represents one attempt to identify how real-world experience might provide natural opportunities to practice this skill, perhaps going some distance in explaining why certain individuals are relatively better able to adapt in the face of new adversities.”

“Students enter college with a wide variety of life experience that helps shape and prepare them for the challenges they’ll encounter in school and beyond. Unfortunately, statistics suggest that many of those experiences could be considered traumatic, such as witnessing or experiencing major accidents or acts of violence,” Hulbert said.

“While these traumas are without question, awful, we wondered whether previous exposure to certain types of trauma might actually enhance future resilience by essentially training individuals to more effectively cope with a range of unwanted memories.”

An experiment with 48 undergraduates found that those who experienced more traumatic events prior to the age of 18 were better at suppressing the retrieval of unwanted memories. These results were replicated in a second experiment with another 48 undergraduates.

“We asked two sets of college students to memorize a number of arbitrary word pairs, like street-violin. After establishing that they had learned the pairings, they were prompted to repeatedly suppress some of those memories (e.g., pushing ‘violin’ out of mind when they saw ‘street’ presented on a computer screen). We call this the ‘Think/No-Think’ task,” Hulbert explained to PsyPost.

“It turns out that those individuals who self-reported relatively more early-life trauma demonstrated a greater ability to forget the memories they were prompted to not think about. The results held, even when they were given money to correctly recall the suppressed memories. And it held both for negative and neutral memories — neither of which were designed to have anything to do with participants’ actual lives.”

“This is consistent with the idea that individuals with relatively higher levels of life adversity are better able to cope adaptively with a wide variety of new memories,” Hulbert remarked. “Overall, these findings suggest that there may be some truth to the old adage, ‘What doesn’t kill you, makes you stronger’ in that traumatic experiences — as horrible as they may be — might naturally contribute to the adaptation of cognitive control skills, thereby improving many survivors’ later resilience, at least those who experienced only moderate levels of trauma and are not predisposed to post-traumatic stress disorder.”

“Theoretically, we hope this work might add perspective to some of the more challenging experiences in people’s lives. Similarly, we hope that we’ve highlighted the adaptive value of forgetting in certain circumstances. Sure, forgetting can be terribly frustrating or embarrassing, but sometimes it’s better (or even healthier) to forget certain memories in the moment—like when information is found to be incorrect, outdated, or problematic to one’s everyday functioning.”

“That’s not to say that there aren’t unintended side effects of a spotless mind, depending on the strategies employed, one’s level of practice with these strategies, available resources, and how circumstances are likely to change in the future.

“In a more applied respect, this work opens up new potential avenues for training memory control. This is certainly not to suggest that people should voluntarily expose themselves to traumatic situations, though there may be value in pushing beyond one’s comfort zones,” Hulbert said.

“More concretely, though, there may be more practical ways of building control skills, using mindfulness training or computer-based tasks. My lab is currently exploring such possibilities.”

The study — like all research — includes some limitations. This particular study utilized a cross-sectional design, preventing the researchers from drawing strong conclusions about causality.

“Given that our study was correlational in nature, longitudinal studies that begin tracking individuals soon after a verifiable trauma would be helpful in better establishing directionality — that is, whether trauma precedes changes in neural and behavioral plasticity,” Hulbert explained.

“Relatedly, it will be important to further characterize the nature and timing of the types of trauma that may lead to this type of adaptation. For instance, are there certain periods of time over the lifespan in which adversity may be more or less likely to contribute to plasticity? Does the severity of the trauma matter? The data we have currently aren’t able to speak to these important questions.”

“By examining an even more diverse population, we could get a better sense of whether even greater levels of trauma history could prove toxic, limiting or undermining the expression of such adaptive benefits,” Hulbert said.

“We are also interested in more closely examining other factors that might influence plasticity—like suppression strategy (which, at least at a cursory level did not seem to matter all that much in the current sample) and even genetics. Doing so would help us get a better handle on the direct and indirect consequences of memory suppression at all timespans.”

“It can be difficult to ensure that a memory that participants do not volunteer on the final test is truly forgotten in the moment. But by collecting trauma-history data in a separate and seemingly unrelated session weeks earlier, by adopting rigorous blinding procedures, and by strongly encouraging participants to report all recalled responses (and adding monetary incentives), our second experiment bolsters confidence that the trauma-history advantage reflects a genuine difference in forgetting of the memories people tried not to think about,” Hulbert said.

“Even if retrieval suppression may be healthy by helping to reduce intrusive memories, recent evidence suggests that this benefit also comes with other costs during the adjustment process. As people recover from trauma, they often exhibit generalized memory deficits — including over-general autobiographical memory and episodic memory impairments.”

“Though clearly not desirable, this temporary decline in memory function may represent a trade-off between the need to regulate intrusive memories that disrupt life on one hand, and general mnemonic functioning on the other.”

“Once intrusive memories have been regulated and control processes refined, memory may improve. Indeed, these types of memory deficits following trauma often abate as intrusions decline.”

“Exposure therapy is generally thought to be effective because it encourages patients to stop avoiding memories and confront associated reminders until they become less distressing,” Hulbert added. “This may sound a bit at odds with our perspective. However, we believe we can reconcile these accounts by highlighting a distinction between avoiding reminders (which doesn’t necessarily build a viable coping strategy) and suppressing the underlying memories after directly confronting reminders, as participants in our experiment were asked to do.

“As such, we suggest that training retrieval suppression abilities may actually demonstrate an ability to augment the benefits of cognitive-behavioral therapy by enabling patients to confront reminders and redirect their thoughts.”

The study, “What Doesn’t Kill You Makes You Stronger: Psychological Trauma and Its Relationship to Enhanced Memory Control“, was authored by Justin C. Hulbert and Michael C. Anderson.