On numerous occasions we have found ourselves arguing with someone else. The causes of a possible debate or discussion are innumerable, but the reader will find it easy to identify with the fact of arguing by remembering an event, happening or conversation differently from someone else.

How can two people remember the same event so differently? Furthermore, how can we not remember well or even remember things that have never happened?

To answer this type of question we must first understand what false memories are , why they appear and what are the brain processes that make them exist.

The fallible operation of memory

Memory is what we use to reach our memories , to repeat some action that led us to the desired result, to locate ourselves or to pass an exam. Now, the difference between our memory and that of any machine is that we constantly deform those memories.

We remember that we have a memory, but this was coded at the time with a specific charge, sensations and emotions, a cognitive state, previous experiences and a context.By accessing it we can recall it, and perhaps access a residue of the emotion experienced in that particular moment; we access a transcription, but the state in which we find ourselves when we recall it is not the same .

Nor are the previous experiences the same, since in the course of time these continue to increase, which leads us to have an image of the past seen from the present , with its consequent interference. In the same way, we can contaminate any event that occurs in the present, if it has been imagined repeatedly before.

Through the expectations, whether they are given by inference in function of previous situations or by mere personal desire, we condition the experience (and therefore the memory) of the present event, since these expectations are also a memory (for example: I remember wishing that everything would be perfect that day) and constitute a consolidated pseudo-learning, that is, something to be expected.

In such a situation, an event with a low negative value can be interpreted as a big problem, or in the opposite situation, an event with a low positive value can be interpreted as something extraordinary. Thus, in this way, this distortion remains codified in the memory , through the imagination that actively shapes reality.

The link between memory and imagination

Given the distortion to which we subject our memory and the interference that the imagination of the future can have in its subsequent interpretation, it seems reasonable to believe that by changing the direction in which this imagination normally operates (forward) and turning it backwards, our memory can be distorted even further, even creating memories of an event that never existed. This is the basis of false memories .

There are, in fact, studies where the possibility of memory and imagination sharing a neural network has been investigated.

The activated areas of the brain when remembering and imagining

In research by Okuda et al, (2003). the role of two structures in the brain, the frontal polar region and the temporal lobes (all of which are involved in future and past thinking), was investigated using positron emission tomography (PET). Regional cerebral blood flow (Rcbf) was also measured in healthy subjects as they discussed their future prospects or past experiences.

Most areas in the medial temporal lobes showed an equivalent level of activation during the tasks related to imagining the future and the tasks related to reporting the past .

In the same vein, another study asked participants to imagine a future event and to recall a past event for 20 seconds with a specific backward or forward projection. Although some differences were found, such as greater activation of the right hippocampus when imagining future events (which the authors believe may be due to the novelty of the event) and greater activation of prefrontal areas involved in planning, similarities abounded.

These results are consistent with those found in amnesiac patients , who in addition to being unable to access memories of past episodes, could not project themselves into a vision of the future.

An example that can be consulted through the scientific databases is the one reported by Klein, Loftus and Kihlstrom, J. F. (2002) in which an amnesiac patient, with the same type of injury and the same problem as those mentioned above. Interestingly, he only suffered this deficit to imagine the future and remember the past in an episodic way , being able to imagine possible future events of public domain, such as political events, who would win the elections, etc. This relates memory and imagination, but also gives it an important nuance, in its episodic form.

Classic experiment for false memories

An example of a classic experiment in the field of false memories is, for example, that conducted by Garry, Manning and Loftus (1996). In it, participants were asked to imagine a series of events that were presented to them. They were then asked to judge how likely they thought it was that this had not happened to them at some point in their lives (in the past).

After some time, in a second session, participants were asked to repeat the experiment and reassign probabilities. Interestingly, the fact that they had imagined it made them assign lower probabilities to their conviction that they had not experienced that event. This is an example of how memories get distorted.

Why is it important to understand what a false memory is?

The importance of these data goes beyond the anecdotal (or not so anecdotal) nature of an argument or the “who said what? For example, one aspect that has been worked on in forensic psychology relatively recently is the attempt to differentiate a real statement from one that is contaminated with false information or distorted information that has been suggested to the person making the statement.

Folk wisdom dictates that if someone tells something that didn’t happen or tells it in a way that doesn’t quite fit reality, it’s because he wants to; he may have ulterior motives or want to deceive someone. With the results outlined earlier in this article, there is at least reasonable doubt about this statement.

Thus, research in this area suggests that the most common sources of error are factors related to perception, interpretation of facts , inference of unprocessed information, the passage of time and post-event information received or imagined. These factors may cause the person to be telling the truth (his or her own) even if he or she remembers something that did not happen.

It is the work of psychologists, but also of any person who wants to go beyond a first impression, to try to analyse these factors as far as possible. Whether we are going to explain or receive an explanation that is relevant to one or more parties, whether in a legal field or in everyday life, it is important to bear in mind that our memory is the result of a process through which the facts we have lived go through, and that this “stored” result, even so, is not in a fixed and unalterable state.