April 3, 2015 6.56pm BST
Authors Joseph Dunsmoor, Post-doctoral Fellow, Psychology, New York University; Vishnu Murty, Post-doctoral Researcher, Psychology, New York University
Human beings are information seekers. We are constantly taking in details – big and
small – from our environment. But the majority of the stuff we encounter in a given
day we rarely need to remember. For instance, what are the chances that you need
to remember where you ate lunch with a friend last Wednesday?
But what if later on you learned that there was something important to remember
about that lunch? The brain has a remarkable ability to store information that seems
inconsequential at the time.
So, if you learn that your friend got sick from what they ordered at lunch last week,
then details from the meal become relevant: which restaurant was it and what did
your friend order? Did you get the same thing? Now those not-so-important details
from lunch aren’t so trivial.
Given new and relevant information, human beings have an amazing capacity to
strengthen weak memories. This points to the adaptive nature of human memory.
Over the past several years, we’ve been interested in understanding how the brain
stores memories for emotionally neutral events that gain significance through
subsequent experience. How does the brain store all of this information? And how
does emotion strengthen mundane memories?
Emotion affects how the brain stores memory. Dr Johannes Sobotta/Wikiemedia Commons
We remember emotional events best
The study of emotional enhancement of memory largely focuses on how we
remember emotionally arousing stimuli or events, like evocative imagery or traumatic
events, like 9/11, which is the subject of a long-term study on what affects memory
retention.
We take for granted that we remember highly emotional events (like 9/11) better than
we remember neutral events, (like that lunch date).
Emotion increases our ability to remember by affecting activity in brain regions
involved in emotional processing, particularly the amygdala and striatum, and also
the regions involved in encoding new experiences, like the hippocampus. Emotion
also increases the strength of our memory over time, a process called consolidation.
Strong emotion can increase memory for positive events, like a surprise birthday
party thrown by your closest friends, and for negative events, like making an
embarrassing faux pas in front of your boss at the office holiday party.
Of course many details are not intrinsically emotionally arousing. But they can gain
emotional significance through our experiences.
For example, the memory of a surprise birthday party includes details like what you
were wearing and who was there. On the face of it, these details are not emotionally
significant, but you remember them because of the context in which they were
experienced.
How do you study memory?
Our research has shown that people have better memory for boring information
when presented in an emotional context, regardless of if it is rewarding or negative.
In some of our earlier studies, we found that people selectively remember neutral
pictures if the pictures had been associated with an electrical shock the previous
day, even when the volunteers were unaware that we would later test their memory.
We have also shown that people remember neutral pictures if they are warned that if
they forget them, they will receive a shock the next day. Likewise,
being rewarded with money for remembering certain pictures the next day can boost
memory for those pictures as well.
These experiments focus on emotional factors at the time the original memory is
created and the findings show how seemingly trivial information associated with a
meaningful event can be selectively preserved in memory.
Memory of small details can be enhanced by their context. Image of photographs via www.shutterstock.com
Emotion enhances our memory of minor details
But what happens when the emotional event happens after the original memories
were formed? In a recent study, we found that an emotional experience can enhance
memory for neutral information encountered previously.
Volunteers viewed a series of trivial pictures from two categories, either animals or
tools. After a delay, volunteers were presented with a new set of animal and tool
pictures – only this time, when the volunteer saw the pictures they received an
electrical shock to the wrist.
We already knew that memory would be strengthened for the pictures paired with the
electrical shock. But here we found that if we paired shocks with pictures of animals,
memory was strengthened for pictures of animals volunteers saw before any shocks
were delivered. If we shocked volunteers when they where shown pictures of tools,
memory for the earlier pictures of tools was strengthened.
Like remembering details from lunch last Wednesday after you discovered your
friend got sick, the negative experience selectively increased memory for related
information that was completely trivial when it was originally experienced.
We use our memory not only to remember the past, but to guide our decisions in the
future. Emotion helps us remember relevant information to determine our choices.
But without the ability to strengthen seemingly trivial past experiences with new
important information, we might end up missing out on future rewards or repeating
the same mistakes.
Disclosure statement
Joseph Dunsmoor receives funding from the National Institutes of Health.
Vishnu Murty receives funding from the National Institute for Drug Abuse.
Partners
The Conversation UK receives funding from Hefce, Hefcw, SAGE, SFC, RCUK, The Nuffield Foundation, The Ogden Trust, The Royal Society, The Wellcome Trust, Esmée Fairbairn Foundation and The Alliance for Useful Evidence, as well as sixty five university members.
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