Mnesic illusion or false memory?

Mnesic illusion or false memory?

False memory, sometimes called mnesic illusion, is a phenomenon linked to the normal structuring and functioning of the brain. It is a widespread and common occurrence in the general population. A false memory is defined as the erroneous memorisation of an element that has not been presented. This can be the result of several failures in the memorisation process, such as partial encoding of an element or an error in the memory construction process.

False memory must be studied macroscopically, since it involves a variety of processes impacting episodic memory, working memory and semantic memory. The appearance of false memories is also strongly influenced by environmental factors such as social and cultural factors, but also by bottom-up mechanisms linked to perception.

A false memory is an event with measurable consequences. For example, several studies have noted an increase in activity in the prefrontal and frontal cortex when false memories occur. Furthermore, false and true memories appear to activate the same areas of the medial superior prefrontal, left precentral and left inferior parietal cortex.

Prevalence of mnesic illusions.

Predisposition to the emergence of false memories.

As a non-pathological phenomenon, false memories can be experienced by anyone. It occurs regardless of age, pathology or intellectual development. Moreover, it would appear that false memories can even be transmitted by social contagion.

False memories with age.

However, comparative studies have shown that some subjects are predisposed to producing false memories. When cognitive decline occurs, particularly with age, there is a redistribution of cognitive faculties to other regions of the brain. This does not come without some weaknesses in the cognitive faculties that become more prone to the emergence of false memories. This is why a number of studies have highlighted the increase in age-related false memories and the associated disability. In some cases, this is even a sign of memory failure.

During the ageing process, the emergence of false memories is more related to intrusions in free recall than to false recognition of the items presented. Current studies seem to show that with age, participants use the gist more than the verbatim according to the fuzzy trace theory of the DRM. This would explain the increase in false recognition by an increase in the number of repetitions only in the elderly groups. All the more so since FMs are often explained by a failure of source control at this age.

There is also an age-related difficulty in dissociating items with semantic or perceptual similarities. This situation echoes the results of studies showing that binding is at a higher level in young people, with 3 pieces of contextual information compared with 1 for older people. Consequently, older people do not use details as effectively as younger people. Finally, older people encode information and details, but are unable to exploit them. Older people are less likely to use memory strategies.

Furthermore, and this is where the increase in false memories poses a problem, older study groups are generally more confident about the veracity of false memories. However, this is less obvious when they are encouraged to concentrate, even though the frequency of false memories remains higher than in younger groups.

The special case of memory illusions and neurodegenerative diseases.

Semantic memory is generally more stable during age-related cognitive decline than episodic memory. This finding is less obvious in individuals suffering from Alzheimer’s disease (AD). Both AD sufferers and the so-called healthy elderly experience a decline in episodic memory. But semantic memory seems to be better preserved in healthy individuals.

The appearance of false memories and a contingent environment?

There are several situations that have an impact on the emergence of false memories. These can be defined according to: the characteristics of the stimulus, the conditions linked to perception and the subject’s abilities (encoding, storage, conditions of recall and recovery).

The appearance of false memories depending on the target.

Generally speaking, the more distinctive features there are in the items presented, the easier it will be for the subject to detect false memories. Among the most effective features are colour and richness of background for images, and structure and semantics for words.

But you need to be able to assimilate the distinctive features, which is not always possible, as we saw earlier. Nevertheless, semantic elements are generally better remembered than perceptual elements. Images, for example, provide stimuli and features that facilitate diagnostic monitoring, but their effect is considerably reduced if they are presented in a set of similar images.

The context has an impact on the resurgence of memory illusions.

At first sight, social relations are beneficial in the face of false memories, since better performance was recorded in groups than individually. Attribution methods used in experiments on false memories have also shown that working in an unsupervised environment provides more distraction, which has an impact on the appearance of false memories.

In addition, the study of false memories around action lists from everyday life has shown that by repeating imagining doing an action, an individual will be more inclined to generate a false memory.

False memories depending on the individual.

Firstly, the appearance of false memories is highly dependent on the individual’s ability to use certain parts of their memory. A poor ability to use episodic memory and the need to resort to semantic memory is a likely consequence of the resurgence of false memories. The same applies to the ability to determine false recognition using processes such as disqualification control, diagnostic monitoring and recall-rejection.

In another way, the relationship with the information presented plays an important role in the creation of false memories. Emotionally charged information is better retained. Emotions seem to accentuate so-called central information and omit second-order information.

From this point of view, emotional memories are more often subject to a phenomenon of reconstruction and can in fact move away from the source memory and create false memories. Imagination can also cause a distortion of memory known as Imagination Inflation.

As far as the individual’s prior faculties are concerned, the more objective knowledge about a subject that can be exploited by the individual, the less likely it is that false memories will emerge. However, new interest in the subject has not been correlated with the emergence or non-emergence of false memories. In the same way, analytical thinking enables us to distinguish true memories from false ones more effectively. Finally, we are more likely to be fooled by misinformation when it is consistent with our beliefs.

Paradigm and research on false memories

Underlying theories and foundations.

False memories are often studied through the prism of semantic similarities using the DRM paradigm. This first paradigm, developed by Roediger & McDermott, enabled the supervised study of false memories. This paradigm and the underlying results can be interpreted mainly by two theories: fuzzy trace theory and source control activation theory.

Fuzzy trace theory.

In the fuzzy trace theory, false memory is caused during the encoding of information or during the general recall of items (Gist) when the distinctive elements (Verbatim) are not solicited. Gist can be defined as the ability of human cognition to grasp a general idea in a scene. Gist is a phenomenon that appears very quickly during visual perception, as it is presented before the first ocular saccade (around 200 ms).

This makes it difficult to study its origin and importance. Verbatim plays an essential role in unifying and recognising information. Finally, in fuzzy trace theory, the Gist and the Verbatim must be used together to estimate true memories from false ones. We generally find that false memories emerge because of a defect in the Verbatim traces compared with the Gist.

The theory of activation and source control.

In the theory of source activation and control, false memory arises as a result of two distinct processes: activation and control. The false memory is the consequence of an abusive association between the internal association on the decoy item and the external associative activation on the DRM items. This can be understood as a misdiagnosis of the source. As a general rule, a reduction in control of the source increases the appearance of false memories.

The activation process occurs several times during the presentation of items, which increases the feeling of familiarity and inhibits the source of activation. This presents the main difference with the fuzzy trace theory by explaining why false memories can appear during the harvesting process and not just because of familiarity.

The paradigm of disinformation.

Apart from the ontological study of false memory, the disinformation paradigm is actively working on the phenomenon of false memory. In this framework, misinformation represents the consequence of false memories appearing under specific conditions. In this case, an individual is subject to false memories following an event that he or she witnesses and from which additional information is later induced and assumed to be true.

The misinformation paradigm is less consensual with respect to the increased emergence of age-related false memories. There was no significant variation in the misinformation paradigm between young and old subjects. Nevertheless, more data is needed to perform a meta-analysis on this subject, as the p statistic in this case is not sensitive enough on current samples.

The social contingency paradigms of false memories.

Finally, other paradigms around false memory deal with the appearance of collective false memories. The social contagion paradigm seems to suggest that false elements can be transmitted through social interaction. Conversely, the retrieval disruption hypothesis suggests that each individual uses a strategy proposed to them when studying items. Group pooling seems to prevent the emergence of false memories.

Research and experimental tools for memory illusions.

In scientific experiments, false memories are often studied in the context of free recall or recognition. Experimental protocols often employ a critical item called a lure, which acts as a trigger for the false memory. The characteristics of the lure are modifiable parameters that have an impact on its effectiveness. In addition, the intensity of the lures within a list is also a factor aggravating the emergence of false memories.

Several semantic models are used in supervised studies, the most common is probably the word2vec model, but there is also the TCC Lexical model which is often put forward.

Studies on mnemonic strategies have shown that they are effective in improving an individual’s ability to discriminate between true and false memories. The Retrieval-based monitoring strategy (RBMS) is one of the most widely cited. It can be implemented in cognitive training programmes to measure its effectiveness.

Photo Maxime Macé

Maxime Macé

Simple passionné de thématiques diverses et variées. J’apprécie enrichir mes connaissances dans les disciplines techniques comme l’informatique, les sciences et l’ingénierie, mais aussi dans les domaines merveilleux de la philosophie, l’art et la littérature.

Prenons contact

Vous souhaitez me contacter suite à la lecture de cet article ? Merci de renseigner votre adresse électronique et je vous recontacterai dans les plus brefs délais.

CV Ingénieur développeur informatique

CV Étudiant PhD Artificial Intelligence

Portfolio Artist designer