A small proportion of the population would be unable to generate the slightest mental image, according to our partner The Conversation.
Recently identified, this peculiarity of the human mind was referred to in 2015 as aphantasy.
The analysis of this phenomenon was carried out by Zoë Pounder, postdoctoral researcher in visual imagery at the University of Westminster (England).
How many times have you been disappointed with a book adaptation for film or television, when a scene didn't quite match what you imagined?
Or that a character did not look at all like what you had envisioned?
Most people, when asked to form an image of someone familiar to them, can “see” it in their mind.
In other words, it is a visual mental representation similar to what we would see if the person were in front of us.
But it turns out that's not the case for everyone.
Some people, when asked to picture a mental image, state that they cannot "see" anything.
This recently identified phenomenon of the human mind was referred to in 2015 as aphantasy.
It is estimated that 2 to 5% of the population are unable, throughout their life, to generate the slightest mental image.
But how do you remember the details of an object or event if you can't "see" it in your mind?
This is a question that my colleagues and I sought to investigate in one of our recent studies.
The study of aphantasy
We assessed the performance of visual memory in individuals with aphantasia compared to those with a typical visual imagination.
In the study, participants were shown three pictures: those of a living room, a kitchen and a bedroom, and were asked to draw them from memory.
Their drawings were objectively reviewed online by over 2,700 external reviewers who compared object details (how they look) and spatial details (the size and location of objects).
We expected that subjects with aphantasia would have difficulty drawing an image from memory because they could not conjure up these images in their minds.
Example of a drawing of an aphantasy participant, from memory, and by observation © Zoë Pounder
In fact, our results showed that they correctly sketched the size and location of objects, but provided noticeably less visual detail, such as color.
They also represented a smaller number of objects compared to the drawings of the witnesses.
Some, finally, noted what the object was by language - for example by writing the words "bed" or "chair" - rather than drawing it.
This suggests the use of alternative strategies, such as verbal representations, which do not require visual memory.
These differences in the details of objects and space were not due to differences in artistic ability or a lack of concentration.
All of this suggests that people with aphantasia have intact spatial cerebral imagination abilities: the ability to represent the size, location and position of objects in relation to each other is preserved. A finding reinforced by another of our studies devoted to their performance in exercises related to memory and its effects on mental representation.
We then found that people who did not have the ability to generate visual images performed as well in these exercises as those with good visual mental representation. We have also seen similar performance with the classic Mental Rotation (RM) technique, where you observe different figures and, by mentally rotating them, determine which are the same.
These results suggest that it is not necessary to have a good visual imagination to perform these tasks.
In contrast, it has been shown that some people with aphantasia - but not all - are more likely to have difficulty recognizing faces and poor autobiographical memory - the memory of life events - a type of memory that it is believed to rely heavily on mental images.
Some people don't have a mental picture of past events © Sun Ok / Shutterstock (via The Conversation)
Living with aphantasy
People with aphantasia also describe other disparities.
Thus, some have only a partial absence of mental image at the level of the senses and will be able to hear a melody in their head… but not have visual images associated with it.
Likewise, research has shown that despite their inability to generate visual images on demand at will, subjects report having mental images in their dreams.
Others say their dreams are non-visual, consisting only of conceptual or emotional content.
These disparities are fascinating and remind us to what extent the distinctions between individuals are still largely unrecognized, especially at the level of perception of the world.
And difference does not necessarily mean less integration.
Many people with aphantasia are not aware of seeing the world differently, and have a very classic working life.
They have even been shown to work in a number of scientific and creative industries.
Our “Brain” file
For many, mental images are an integral part of how they think, remember past events, and plan for the future - a process they engage in and experience unconsciously.
We do not yet understand why there are differences in visual mental representation, or what is the root cause.
But what aphantasy testifies to is that many of our major mental experiences are in fact not universally shared.
There are therefore many unrecognized and disconcerting disparities between us, which have continued to titillate scientists.
Health
Mental health: Why victims of mental health disorders age (and die) prematurely
Health
Alzheimer's: What types of forgetfulness cause the disease and to which areas of memory are they linked?
This review was written by
Zoë Pounder
, postdoctoral researcher in visual imagery at the University of Westminster (England).
The original article was published on
The Conversation website
.
Declaration of interests
Zoë Pounder does not work, advise, own shares, receive funds from any organization that could benefit from this article, and has not declared any affiliation other than her research organization.
Neurology
Picture
Memory
Brain
Health
The Conversation
Video