For most people, the ability to mentally imagine different things, to visualize objects, situations and processes in the brain seems to be a natural phenomenon. For example, imagine an endless series of sheep jumping over a fence so that this monotonous sight helps to fall asleep. It is all the more surprising to learn that there are people with congenital "aphantasia" who are not capable of this in principle.
The term "aphantasia" itself is not very accurate, because we are not talking about fantasy as such. This is not a mental disorder, not an illness or a peculiarity of thinking, but something like congenital blindness. Those who have never seen the light do not experience any particular difficulties because of this, they have learned to perceive the world differently than sighted people. In the case of aphantasia, we are talking about the use of a person's memory in a non-standard mode.
In the last major experiment on the subject, participants were shown photographs of several interiors and asked to draw them. The first time immediately after viewing the image, and the second after a while, from memory. The results were evaluated by 2795 experts, they studied the subject and spatial details of the drawing. The subjects with aphantasia did not cope with the second task, they could not reproduce the objects in the picture. Instead, for example, one participant drew a rectangle and wrote a "window" on it.
With aphantasia, a person retains all cognitive abilities, but when information is recorded in long-term memory, it gets there not in the form of images, but with the help of “verbal coding”. Such a person quite accurately remembers the proportions, distances between objects, their essence, but not their appearance. What is even more interesting, they have no false memories, for example, in the same experiment, an ordinary person finished painting a non-existent piano in the corner of a room. Because it was appropriate there, based on the general style of the interior, that's why his brain thought out this object. With aphantasia, this is impossible.