Memory-zapping devices like those in "Men in Black" and "Eternal Sunshine of the Spotless Mind" could soon be a thing of the past (if they were ever a thing at all), as researchers have now discovered a much cheaper and less complicated way to erase unwanted memories. According to a new study that appears in the journal Psychonomic Bulletin and Review, the key to forgetting could lie in simply changing the way we think about the “context” surrounding our memories.

Context is quite a broad thing that can be hard to pin down. Essentially, it refers to everything else that’s going on around a particular event, and, according to the study authors, has a huge influence over how memories are “organized and retrieved” by the brain. For example, if you happen to have a bad experience after drinking too much tequila (itself a pretty effective memory eraser), then it’s likely that the very thought of taking another shot of the stuff will dig up unpleasant memories of that experience.

While you’ll probably only have yourself to blame for getting too drunk and putting yourself in a particular spirit, people who experience more serious distressing events can sometimes develop post-traumatic stress disorder (PTSD), whereby certain contextual cues cause them to relive painful memories. If sufferers can learn to dissociate these memories from their context, however, it may be possible to alleviate their PTSD.

To test whether this is possible, researchers from Princeton University and Dartmouth College subjected volunteers to a memory test, in which they were shown a list of words that they were told either to memorize or forget. In between viewing each word, they were shown an image of a natural landscape, such as a mountain or a forest, in the hope that they would automatically associate the memory of the words with this contextual cue.

People who experience distressing events often suffer from post-traumatic stress disorder. John Gomez/Shutterstock

While this was going on, the researchers used functional magnetic resonance imaging (fMRI) to observe participants’ brain activity, noting the neural patterns that occurred as they encoded these contextual images.

Subjects were then asked to try and recall the word lists, while researchers once again measured their brain activity using fMRI. Results showed that those who had been told to remember the lists tended to replay the same neural patterns associated with context when recalling the words, indicating that the memory and its context had become intertwined in their brains.

However, those who did not remember the lists did not repeat this neural pattern when unsuccessfully attempting to recall the words, suggesting that the event and its context had not become entangled in their minds. Importantly, the degree to which this contextual recall was diminished correlated directly to participants’ ability to remember the words from the list.

Lead researcher Jeremy Manning explained in a statement that this process is similar to “pushing thoughts of your grandmother's cooking out of your mind if you don't want to think about your grandmother at that moment.” Having now identified this as a mechanism for forgetting, he hopes to see his work used as a platform to develop a range of new memory therapies.

“For example, we might want to forget a traumatic event, such as soldiers with PTSD. Or we might want to get old information 'out of our head,' so we can focus on learning new material,” he said.