Actively suppressing negative experiences may help prevent intrusive thoughts and rumination. The corresponding study was published in eLife.
Unwanted memories can be triggered by harmless objects related to the experience- such as a teddy bear of an injured child. Earlier research has found that if such memories are actively pushed out of one’s consciousness, they become more difficult to remember later on. Until now, however, whether or not they ‘fade away’ has been unknown.
In the present study, researchers sought to investigate whether these memories really 'fade away' after being suppressed. To do so, they enrolled 33 participants and taught them to associate pictures of negative experiences with neutral objects, such as a flood disaster with a rubber boot or a car accident with a lost shoe.
They were then shown the objects and either asked to recall the negative experiences or suppress them while being observed via fMRI. In the final step, the participants were shown the objects once again and asked to recall each scene. This allowed the researchers to see if suppressing memories earlier made them more difficult to recall later.
In doing so, they found that suppressing memories earlier made them less vivid when recalled later on. Using a pattern classifier, the researchers observed how suppression diminished the neural reactivation of scene information globally across the brain and locally in parahippocampal cortices.
“Forgetting has a largely bad reputation,” says Dr. Roland Benoit, study leader and head of the Adaptive Memory Research Group at Max Planck Institute for Human Cognitive and Brain Sciences.
“However, active forgetting may be a helpful mechanism to prevent memories of bad experiences from constantly intruding into our awareness. By controlling our thoughts, we can weaken our memories and possibly erase their neural traces in the brain," he said.
The researchers say that it is not yet clear why some people forget more easily than others. For example, it is typically more difficult for people with depression or post-traumatic stress disorder (PTSD) to forget than people without the conditions. The researchers say that future studies could determine whether and how deliberate forgetting contributes to mental health.