14 DAY TRIAL // A team of experts with the Cognition and Brain Sciences Unit at the Medical Research Council (MRC) and the Behavioral and Clinical Neuroscience Institute (BCNI) at the University of Cambridge discovered in a new study that suppressing unwanted memories tends to lead to a decrease in their influence on human behavior. Additionally, the group learned more about how this process occurs.
Previous investigations have suggested that suppressed memories remain stored in the unconscious mind at all times, regardless of how much patients or their therapists want to get rid of them. The new study challenges this hypothesis, suggesting that actively trying to suppress negative memories creates a negative feedback loop that affects the areas of the brain in charge of sensory processing.
In the past, researchers thought that suppressed memories could seep into someone's behavior, even if unconsciously, and influence it to a noticeable extent. This conclusion could not be supported with evidence collected in the new study. The work, which was partially funded by the MRC, is detailed in the latest issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS).
In a series of experiments, scientists with the joint UK research group used a brain-imaging technique called functional magnetic resonance imaging (fMRI) to investigate test participants' responses to viewing a series of word-picture sets. The goal was for subjects to remember an image every time the word associated with it was spoken.
Participants were surveyed either when they were asked to let themselves remember the image, or when they were told to try and prevent the image from popping up in their heads. The team established that people who actively suppressed their memories found it harder to remember the same object later on, after viewing another series of images.
The reason why this type of study is so important is that it may have direct implications on treating conditions such as post-traumatic stress disorder. PTSD is characterized by uncontrolled, intrusive memories popping up in patients' heads at all times, decreasing their quality of life and leading to anxiety and depression.
“While there has been a lot of research looking at how suppression affects conscious memory, few studies have examined the influence this process might have on unconscious expressions of memory in behavior and thought,” explains MRC CBSU investigator, Dr. Michael Anderson.
“Surprisingly, the effects of suppression are not limited to conscious memory. Indeed, it is now clear, that the influence of suppression extends beyond areas of the brain associated with conscious memory, affecting perceptual traces that can influence us unconsciously. This may contribute to making unwanted visual memories less intrusive over time, and perhaps less vivid and detailed,” he explains.