A new paper, published in the journal Nature Neuroscience, indicates that internal physiological and brain states that persist in the aftermath of an emotionally taxing event can have an impact on the way we attend to and remember future experiences.
“How we remember events is not just a consequence of the external world we experience, but is also strongly influenced by our internal states – and these internal states can persist and colour future experiences,” explains study lead author Lila Davachi from the Department of Psychology and the Centre for Neural Science at NYU.
According to Davachi, the study shows that brain states we call “emotions” are tightly linked to our cognition and tend to influence our day-to-day experiences for a long time even after the initial trigger is no longer there.
While the idea that emotionally charged events are remembered better than largely non-emotional events has been extensively tested and shown to be correct, what the new research shows is that experiences devoid of strong emotional involvement that follow more emotional experiences are also retained better on a delayed memory test.
Study participants were divided into two groups. The first group watched a series of emotionally arousing images and then a series of neutral images that were shown 9-33 minutes after the first batch. The second group did the exact opposite. During the trial, skin conductance and brain activity were measured in all subjects.
Six hours later, both groups were administered a memory test designed to measure how well they remembered the viewed images. Results showed that subjects who were shown emotion-evoking stimuli first were significantly better at remembering the subsequent neutral images, compared to subjects who saw the same neutral images before the emotional ones.
For a possible explanation, the researchers turned to the fMRI data, which was collected throughout the study. This showed that brain states associated with emotional experiences carried over for 20 to 30 minutes and influenced the way the subjects processed and remembered future experiences that are not emotional.
“We see that memory for non-emotional experiences is better if they are encountered after an emotional event,” concluded Davachi.