Erasing a memory takes more brain power than recalling a memory, neuroscientists have found.
To forget an experience, the mind needs to focus some attention on dealing with it, but not too much.
Memories are strengthened when we linger on them for too long.
People can forget memories by redirecting their attention away from them and by actively suppressing their retrieval.
While it is hard, discarding memories is possible, the research shows.
Dr Jarrod Lewis-Peacock, study co-author, said:
“We may want to discard memories that trigger maladaptive responses, such as traumatic memories, so that we can respond to new experiences in more adaptive ways.
Decades of research has shown that we have the ability to voluntarily forget something, but how our brains do that is still being questioned.
Once we can figure out how memories are weakened and devise ways to control this, we can design treatment to help people rid themselves of unwanted memories.”
For the study, a group of people were shown pictures of faces and scenes.
Sometimes they were told to try and remember them, other times to forget them.
Brain scans revealed that people have the ability to control what they forget.
However, forgetting requires more brain activity in key areas than remembering.
Dr Tracy Wang, the study’s first author, said:
“A moderate level of brain activity is critical to this forgetting mechanism.
Too strong, and it will strengthen the memory; too weak, and you won’t modify it.
Importantly, it’s the intention to forget that increases the activation of the memory, and when this activation hits the ‘moderate level’ sweet spot, that’s when it leads to later forgetting of that experience.”
The study also found that scenes were easier to forget than faces.
Faces have more links to the emotions, which makes them lodge in the mind more easily.
Dr Lewis-Peacock said:
“This will make way for future studies on how we process, and hopefully get rid of, those really strong, sticky emotional memories, which can have a powerful impact on our health and well-being.”
The study was published in The Journal of Neuroscience (Wang et al., 2019).