Memory formation is closely tied to our emotions. Could we use our emotions to mold our memories?
by Isabelle Guo, Contributing Writer
Picture your most vivid memory. Perhaps you can recall it so clearly that you can walk around in its afterimage–run your fingers over the cold metal of a railing, see the pinpoints of a hundred stars against an ink-black sky, hear the shouting in the other room. Who was there? Can you feel now what you felt before–your anger, joy, fear, wonder, grief? Chances are your sharpest memories are also your most emotional ones. This is by design: far from being shiny decoration to our cognitive processes, emotions play a critical role in deciding what we remember. Many neuroimaging studies show that emotional intensity and mood are linked to memory via hippocampus-amygdala association. By understanding more about how memories are made and stored, perhaps we can leverage cognitive functions and emotions to improve how quickly we learn or how much we can remember–the possibilities are endless.
The link between emotion, memory and behaviour is rooted in evolution. Feelings form the basis for the fight or flight response, priming the body with physiological changes in heart rate, temperature, and reaction speed (1). In addition, homeostatic imbalances–hunger, thirst, hypothermia–can induce anger, sadness, and frustration, driving pro-social behaviour and resource-seeking survival instincts. Emotion pulls us towards things that feel good, such as energy-rich food or making social connections, and away from painful and threatening events such as rocks or predators. The more intense a stimulus is, the more important it would be to remember to maintain our homeostatic drives and survive. As a result, we remember events with high emotional scores most vividly. In today’s context, our biological wiring is what makes us remember tiny, embarrassing slip-ups for years afterwards but forget our formulas at the exam table–while biologically necessary, the memories we keep and the memories we lose are not always in alignment with our modern-day needs. If we wish to emotionally regulate our memories, we must first understand the neurobiology behind memory storage and retrieval.
Memory processing is driven by complex interactions between the hippocampus, the amygdala, and the prefrontal cortex. Roughly put, the hippocampus is involved in learning and long-term memory while both the amygdala and the prefrontal cortex are implicated in different types of emotional dimensions: valence and arousal (1). Valence, associated with prefrontal cortex activity, describes the negative or positive nature of an emotion. For example, joy has very positive valence, while frustration has negative valence. Arousal, associated with the amygdala (2), describes the intensity of emotion: boredom would be a low-arousal state, while terror would be a high-arousal state. While studies on the effect of valence on memory remain inconclusive on whether negative or positive valence lends itself to better memory recall, arousal is found to correlate strongly with memory formation and with hippocampal memory encoding. In a neuroimaging study by Richardson, Strange, and Dolan, study participants with hippocampal sclerosis–an illness that impairs memory, along with other hippocampal and perhaps even amygdala functions–were selected. Participants were then shown a series of 288 words, with a small portion (12.5%) of those words being emotionally charged (i.e. “cancer”). When asked to identify whether or not they had been shown a word, participants with amygdalar damage from hippocampal sclerosis otherwise had similar recall capabilities as those without amygdalar damage; however, they had lower recall rates for emotionally charged words. FMRI images taken from the same study showed a clear modulating effect between the hippocampus and amygdala (3). This study implies two conclusions. Firstly, emotional intensity directly modulates and interacts with the regions of the brain that encode memories. Secondly, intensity of the emotional stimulus is the deciding factor for how deeply memories are encoded.
If the intensity of emotional stimulus–hinging largely on external factors–determines how much we remember, how can we hope to harness emotion as a tool for memory? Wilfully controlling our emotions and perceptions of events, such as tuning out an irritating neighbour, is a top-down cognitive process associated with cortical brain regions such as the prefrontal cortex. Remarkably, the amount we suppress or express our emotional states can influence our recall of events. In a 2016 study by Richards and Gross on emotional repression and its effect on memory, participants were separated into two study groups and were shown emotionally charged flashcards. When study participants were asked to repress their emotional expression, their memory of the cards was reduced from the control group, indicating that emotional suppression bears the cognitive cost of reduced memory capabilities (4). The research implies that by avoiding deliberate emotional repression, we will be able to recall memories with greater clarity and for longer periods of time. When we emotionally disengage and suppress our affect, catching our behaviour and taking care to express ourselves may cement important information in our memories, allowing us to recall it with greater clarity and ease.
Neurobiological research into the emotion-memory relationship is imprecise by virtue of how little we know about the brain; regardless, elucidating a relationship between emotional cortical regulation, amygdalar arousal response, and hippocampal memory encoding is invaluable. Conscious emotional states have a tangible impact on what we remember and whether we remember at all. Perhaps by consciously tuning our sensitivity to emotional experiences as well as emotional expression, we can improve and control our memories. Learning more efficiently in classrooms by incorporating more interesting, emotionally charged tasks in our study materials, we might recall more lecture content and elevate learning beyond rote memorization (1). We may learn to preserve cherished moments with friends and family by expressing our feelings with less inhibition in the moment. With more research into memory disorders, we may someday leverage emotional cues to stir memories in those with depressive amnesia or Alzheimer’s patients, improving cognitive performance and increasing personal fulfilment. As our knowledge of cognition and emotion progresses in leaps and bounds, the future of memory preservation is taking clearer form. Our possibilities are as boundless as our imaginations.
Edited by Ivy Sun
- Tyng, C. M., Amin, H. U., Saad, M. N., & Malik, A. S. (2017). The influences of emotion on learning and memory. Frontiers in Psychology, 8. https://doi.org/10.3389/fpsyg.2017.01454
- Kensinger, E. A., & Corkin, S. (2004). Two routes to emotional memory: Distinct neural processes for Valence and arousal. Proceedings of the National Academy of Sciences, 101(9), 3310–3315. https://doi.org/10.1073/pnas.0306408101
- Richardson, M. P., Strange, B. A., & Dolan, R. J. (2004). Encoding of emotional memories depends on amygdala and hippocampus and their interactions. Nature neuroscience, 7(3), 278–285. https://doi.org/10.1038/nn1190
- Richards, J. M., & Gross, J. J. (1999). Composure at Any Cost? The Cognitive Consequences of Emotion Suppression. Personality and Social Psychology Bulletin, 25(8), 1033–1044. https://doi.org/10.1177/01461672992511010