Self-Motivation
David Goggins
Former Navy Seal
Career Development
Bryan Cranston
Actor
Critical Thinking
Liv Boeree
International Poker Champion
Emotional Intelligence
Amaryllis Fox
Former CIA Clandestine Operative
Management
Chris Hadfield
Retired Canadian Astronaut & Author
Learn
from the world's big
thinkers
Start Learning

Preliminary evidence that stress makes negative memories less distinctive, with implications for witness testimony

Studies on stress and memory have often given conflicting results.

Andrew Harrer/Bloomberg via Getty Images

Stress has complicated effects on our memories.


Whereas some studies have found that we are better at remembering events that occurred during stressful situations, such as while watching disturbing videos, others have shown that stress impairs memory. Now a study published in Brain and Cognitionsuggests that stress doesn't influence the strength of our emotional memories at all. Instead, the researchers claim, it is the fidelity of those memories – how distinct and precise they are – that changes when we go through stressful experiences.

Maheen Shermohammeda from Harvard University and colleagues recruited 56 young adults between 18 and 23, and asked them to view a series of negative and neutral pictures. That might seem painless enough – except that half of the participants looked at the pictures while feeling rather stressed. Before they began looking at the pictures, they were told that they would later have to give a speech to a panel of judges. To make matters worse, before seeing each block of pictures they had to complete complicated maths problems. They were given just a short time to complete these, and while doing so they were told that they were performing poorly and their data would be unusable if they didn't do well. In contrast, the control group had a fairly relaxing time: instead of a speech, they were told they would have to write a story, and they only had to complete simple maths problems at their own pace.

About two weeks later, all the participants were given a surprise memory task, in which they again saw the earlier pictures alongside new images they hadn't seen before. They had to indicate whether each picture was an old one that had been in the original task or a new image they hadn't seen before.

At several points throughout the study, all participants were asked how stressed they were, and also had their heart rate measured and saliva samples taken to analyse levels of the stress hormone cortisol. As expected, the group that went through the stressful experience reported higher levels of stress, and had increased heart rates and cortisol levels (although the team had to exclude a handful of participants who, surprisingly, didn't report feeling stressed).

Overall, participants in both groups were better at remembering negative images – this replicates a well-established finding that emotional material tends to be more memorable. Also, the stressed group correctly remembered just as many of the earlier images as the control group (i.e. their "hit rate" was the same). Crucially, where the groups differed was in their patterns of "false alarms" – how often they falsely remembered new images as being from the original task. The stressed participants were more prone to false alarms for negative images compared neutral images, and the more stressed they were, the larger this difference.The control group didn't show any difference between the two kinds of images.

Based on these results, the researchers suggest it's not the strength of our memories that is influenced by stress, but rather their fidelity, or how distinct they are from other information. For the stressed group, neutral memories became more distinct, making it easier to distinguish them from new neutral material, while negative memories were more vague or blurred, making it harder to distinguish them from new negative material. The results demonstrate the importance of separating out memory into its constituent parts (strength and fidelity), the researchers add, rather than just looking at overall performance or correct "hits".

It's clearly a rather preliminary result. The pool of participants was small to begin with, and made even smaller after the researchers had to remove those participants who didn't respond to their stress intervention. And the participants all came from a very young, narrow age range, raising the question of whether older people respond in similar ways.

Nevertheless, the idea that stress has different effects on different components of memory is an interesting proposition that deserves further attention – particularly as understanding memory during periods of stress has important real-world implications for situations like eyewitness accounts of crimes. For example, the researchers said, a "stressed witness to [a] crime … may indeed have a strong recollection of the criminal, but may also have an impoverished ability to discriminate the assailant from other individuals in a police lineup."

Stress impacts the fidelity but not strength of emotional memories

Matthew Warren (@MattbWarren) is Staff Writer at BPS Research Digest.

Reprinted with permission of The British Psychological Society. Read the original article.

Is the universe a graveyard? This theory suggests humanity may be alone.

Ever since we've had the technology, we've looked to the stars in search of alien life. It's assumed that we're looking because we want to find other life in the universe, but what if we're looking to make sure there isn't any?

According to the Great Filter theory, Earth might be one of the only planets with intelligent life. And that's a good thing (NASA, ESA, and the Hubble Heritage Team [STScI/AURA]).
Surprising Science

Here's an equation, and a rather distressing one at that: N = R* × fP × ne × f1 × fi × fc × L. It's the Drake equation, and it describes the number of alien civilizations in our galaxy with whom we might be able to communicate. Its terms correspond to values such as the fraction of stars with planets, the fraction of planets on which life could emerge, the fraction of planets that can support intelligent life, and so on. Using conservative estimates, the minimum result of this equation is 20. There ought to be 20 intelligent alien civilizations in the Milky Way that we can contact and who can contact us. But there aren't any.

Keep reading Show less

Study details the negative environmental impact of online shopping

Frequent shopping for single items adds to our carbon footprint.

A truck pulls out of a large Walmart regional distribution center on June 6, 2019 in Washington, Utah.

Photo by George Frey/Getty Images
Politics & Current Affairs
  • A new study shows e-commerce sites like Amazon leave larger greenhouse gas footprints than retail stores.
  • Ordering online from retail stores has an even smaller footprint than going to the store yourself.
  • Greening efforts by major e-commerce sites won't curb wasteful consumer habits. Consolidating online orders can make a difference.
Keep reading Show less

Childhood sleeping problems may signal mental disorders later in life

Chronic irregular sleep in children was associated with psychotic experiences in adolescence, according to a recent study out of the University of Birmingham's School of Psychology.

A girl and her mother take an afternoon nap in bed.

Personal Growth
  • We spend 40 percent of our childhoods asleep, a time for cognitive growth and development.
  • A recent study found an association between irregular sleep patterns in childhood and either psychotic experiences or borderline personality disorder during teenage years.
  • The researchers hope their findings can help identify at-risk youth to improve early intervention.
  • Keep reading Show less
    Videos

    Why do people believe in conspiracy theories?

    Are we genetically inclined for superstition or just fearful of the truth?

    Scroll down to load more…
    Quantcast