"Life is a dream," he said Calderón de la Barca, but not all life. At least not at the neuronal level. Our brain has a way, quite rough, to differentiate what is reality or fiction: basically, if there are many parts of the brain that are activated when a memory is evoked, it is that that memory is real.
On the contrary, if we imagine something or evoke something false, then the areas in charge of processing images, to begin with, will not reflect such an intense activity. The problem with this crude system is that it can be violated with relative ease: memory traces based on something false can be expanded until they artificially reach the same size as a true story.
To test how simple it is to implant false memories, almost as if we had gone to the company of Total Recall fleeing from our daily life as a construction worker to imagine an alternative life as a secret agent on Mars, it was carried out a study in participants who were shown a series of different photos of everyday situations.
The next day, the participants received some short phrases that recalled the photos of the previous day, but what they did not know is that some of these new statements were misleading and misrepresented the photo.
Brain activity in the case of correct and false memories was so similar that some of the participants formed misconceptions of the original images. The difference between true and false memories was only in brain activation: the visual area was activated more if the memory was true (because I had actually seen the photos) or the auditory processing area if they were false (because the new information heard it had mixed with the memory). As abounds in it Henning Beck in his book To err is useful:
This experiment also clearly demonstrates that the memories are not static, but that they can be modified a posteriori, specifically, each time a memory is re-fished. And it is just in this state when the memory is more sensitive to external influences.
In the real world, this problem can have serious implications, such as the scandal of false memories induced by therapists about rapes in childhood. Their techniques, consisting of questions that hinted at the appropriate response, reinforcement of concrete answers and much repetition, inadvertently caused hundreds of adults to believe that they had received sexual abuse in the 1980s by preschool teachers. As he points out David Linden in The accidental brain:
The problem of suggestibility is even greater in children, especially in preschoolers. In a typical study, a bald man visited a group of preschoolers in the classroom, read them a story, played with them for a short time and then left. The next day, these children were asked a series of non-linear questions such as "What happened when that man came to visit you?", And the children responded by telling a series of memories that, while not complete, were quite accurate. . But when they were asked questions that somehow suggested the answer they wanted to get, like "What color was the hair?", Then a large number of children chose a color. Even those children who initially responded that the man had no hair on his head, began, especially since the question was repeated several times in different sessions, to fabulate and further expand the false memory.
Thus, memories are not so much a way of keeping in mind the past as a way of building ourselves and giving coherence to our actions and thoughts, even if it means doing so somewhat awkwardly and sensitive to external influences.