Steven Brightup, a first-year graduate student in materials science engineering, remembers being confused as he woke up and heard his mother telling him about the attacks of Sept. 11, the way he yelled the news to his dad as he was coming back from a morning walk, and watching the news in his English class.
Similarly, most students can recount in detail the experiences and thoughts they had immediately after the attacks of Sept. 11.
Or at least they think they can.
Many people’s most vivid memories are of highly emotional events, and research has shown that while emotion does play some role in increasing memory, people are only slightly better at remembering the details of emotional memories than neutral memories.
“People who don’t study memory have the idea that memory is like a tape recorder and that everything they remember is exactly true when it clearly is not,” said Russell Poldrack, professor of psychology.
The phenomenon of having photographic-like memories of emotionally significant events is known as flashbulb memory and is clearly seen in our remembrance of Sept. 11.
Even though people feel very confident that their emotional memories are accurate, those questioned on Sept. 12 about the details of the previous day and then a year later were not significantly more accurate describing the attacks than daily life events before Sept. 11, Poldrack said.
“These memories feel very strong but are often inaccurate,” Poldrack said. “Emotion is really turning up people’s confidence but not increasing the accuracy of the memory very much.”
While emotion does not burn things into memory the way the flashbulb memory phenomenon suggests it might, memory can somewhat be improved by emotional experiences, Poldrack said.
Chemicals such as dopamine and norepinephrine are released in the brain in response to any type of stress, and enhance human memory ability, said David Glanzman, professor of physiological science and neurobiology at UCLA.
Glanzman has spent 25 years studying learning and memory in the marine snail Aplysia, which is found along the California coast and believes there are many parallels between the memories Aplysia can acquire and human memory.
When Aplysia receives a shock, the neurotransmitter serotonin is released.
This increases the strength of the synapses between the neurons that mediate reflexes, encoding a memory of the event so that it will react quickly to any future aversive stimuli.
In humans, dopamine and norepinephrine are brain chemicals that perform the same role serotonin does in Aplysia, strengthening synapses by triggering a cascade of molecular events that produce long-term memory, Glanzman said.
“The mechanisms we study on a cellular level in the snail are very similar to the cellular mechanisms of learning memory in us,” Glanzman said.
When people are in a highly emotional state, they are more likely to encode memories that they will later remember due to the interaction of different areas of the brain, including the hippocampus, which controls memory, and the amygdala, which is involved in emotional arousal, Poldrack said.
Brightup agrees that the majority of things he remembers in great detail are attached to emotional thoughts.
“I was deathly afraid the first time I had a solo in jazz band in junior high,” Brightup said.
“I remember every detail very well and how nervous I was as I sat waiting to begin my solo.”
But he also realizes that memories are influenced by our current understanding of the world, Brightup said.
“Whenever I remember something from the past it is influenced by my newfound knowledge and context,” Brightup said.
“It is harder to remember something as I initially remembered it because I have changed my perspective.”
Emotion thus has a strong role in helping people remember experiences, Poldrack said.
But the memory of the past emotional event is often not entirely accurate since it is influenced by new information, he added.