Minds incapable of evoking images: this is how a brain with aphantasia works

Imagine a Christmas tree. Or try to visualize in your mind the last meal you had yesterday. Also try to remember the face of a family member you haven't seen in a while. Surely, most of you have been able to evoke those mental images without any problem, perhaps with more or less precision and vividness of details, but with the same naturalness with which you visually relive every day the shape of objects, people or lived experiences. . However, there is a percentage of people, around 1% of the population, who are unable to do this exercise: they are those individuals who have aphantasia, a neurological characteristic that prevents creating conscious images in the mind. A scientific review has recently delved into the still limited knowledge of this trait and has concluded that it is associated with a reduction in autobiographical memory and facial recognition. It is also more common in people with autism and in individuals with a tendency toward scientific occupations.

The imaginary contains all that experience of the sensory properties of objects or activities when they are absent, such as the appearance of an orange or the sound of thunder. And through an intricate neurological process, images often come to mind. However, people with aphantasia are incapable of constructing internal images, of visualizing through thought. Although this does not mean that they do not have imagination, qualifies Adam Zeman, professor at the University of Exeter (United Kingdom) and author of the scientific review. “It means a lack of visual imagery and, often, also of other sensory imagery, but people with aphantasia can be imaginative in the sense of creativity,” explains the scientist, who has published his article in the journal

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To begin with, aphantasia is not a disease. Rather, it is a characteristic that explains how an individual processes information and that, “occasionally, can be a symptom of a neurological or psychological disorder,” Zeman explains. An injury to the brain or the evolution of a pathology can trigger a loss of the ability to evoke visual images in the mind, but this trait is usually hereditary and permanent. And healthy people who experience it are fully functional.

In this sense, the neuropsychologist at the Sant Pau Hospital in Barcelona, ​​Saul Martínez-Horta, emphasizes that “normality in human cognition is diverse” and can function in very different ways. In aphantasia, he notes, “how the neurological systems dedicated to processing visual information are organized are probably different,” but that doesn't have to be disabling. “When something has always happened in the absence of impact on daily life, it does not indicate anything. But the sudden appearance of something, such as the inability to project images in the mind, can be an indicator that something has happened,” explains Martínez-Horta, who has not participated in this research. Psychiatrists have reported the appearance of aphantasia in contexts of depression, depersonalization and psychosis, among others.

Zeman's scientific review describes that 1% of the population experiences profound aphantasia, although there is a very variable spectrum and they also highlight that between 2% and 6% of citizens have a "vague and tenuous" visual imagery. There is also, on the other side of the coin, around 3% of the population who show just the opposite, hyperfantasy, which is the ability to generate hyperrealistic images in the mind. “There is a whole spectrum of evocative capacity, but there is no standard assessment and it is very difficult to qualify it. “It is probably a birth pattern,” says Javier Camiña, member of the Spanish Society of Neurology, who has not participated in this research.

According to scientists, aphantasia is overrepresented among people who work in mathematical, computational and scientific roles, a phenomenon that Martínez-Horta associates with convergent thinking. “In convergent thinking, when you consider the uses of a pen, the thinking is rigid and methodical: it is used for writing; On the other hand, divergent thinking is more childish, the pen can be a weapon or to tie your hair. Aphantasia is associated with a convergent pattern, more confined to the foreseeable,” she says. In traditionally more creative industries you are more likely to find individuals with hyperfantasy.

Less autobiographical memory

In experimental measurements of memory, people with this neurological trait have also shown mild to moderate impairment. “In accordance with the close relationship between remembering the past and imagining the future, the richness of descriptions of imagined scenes is also reduced in aphantasia. “Aphantasia similarly reduces the detail of eyewitness testimony,” Zeman notes in his article. Autobiographical memory, which is the memories of a person's life, is also reduced in these individuals, to the point of coexisting with a syndrome in which the sufferer lacks vivid first-person memories about their life history, although it is able to function normally on a daily basis.

Scientists are still trying to unravel how a brain with aphantasia operates. “The key difference is probably in connectivity, with a stronger connection between thinking regions and sensory regions in people with more vivid images,” defends Zeman. Camiña agrees that there are probably “differences in the modulation of the processes” that participate in the brain's perceptual capacity. “In the absence of a stimulus, brain structures such as the prefrontal cortex are involved; also the limbic system, because we have to evoke previous memories; and the fusiform gyrus, involved in face recognition. “Rather than structurally altered zones, there may be abnormal regulation of connectivity between these areas.”

Another peculiarity of aphantasia, in fact, is the difficulty in recognizing faces: around 40% of people who experience this neurological characteristic admit difficulties with facial recognition, more than double the frequency of people without this trait. The studies analyzed by Zeman also show that people with aphantasia have higher scores on questionnaires to measure the autism spectrum.

Zeman also suggests that aphantasia “may offer some protection against some mental health conditions,” because some work has suggested that a high capacity to create images in the mind may be a risk factor for hallucinations in schizophrenia and Parkinson's, as well as for Visual intrusions in posttraumatic stress. However, the experts consulted are cautious and qualify this idea. “Probably, if that person has schizophrenia or Parkinson's, he will have different hallucinations, possibly fewer symptoms. But it is not a protective pattern. "A person with underlying hyperfantasy, if they suffer from post-traumatic stress, will have the ability to relive the traumatic episode and will present more frequency, intensity or duration of symptoms," says Camiña.

ability to dream

Paradoxically, although aphantasia prevents the evocation of conscious images, people with this neurological characteristic can dream. “It is probably explained by the fact that the route to the imaginary in the brain is very different in the voluntary imaginary in the waking state compared to the imaginary in dreams,” Zeman assesses. Aphantasic people are capable of having dreams with visual qualities, although studies describe avisual dreams, "with variable narrative, textual, conceptual, auditory and emotional content" more frequently than participants without this trait, the scientific review states. .

Experts admit that the identification of aphantasia is complex because there are no infallible detection tests and there is a high level of subjectivity in perception. “Explaining how I see my internal world is very difficult. A person with difficulties in constructing internal images does not know this. “The majority discover aphantasia when they read about it in some media,” says Martínez-Horta. But just because it is complex does not mean that it does not exist or that everything is a product of one's own perception. Zeman points out that there is already behavioral, physiological and neuronal data that reveals the differences between the traits of this spectrum. And he gives an example in the article: “While normal participants who listen to extremely frightening stories show an increase in the galvanic skin response (they sweat!), people with aphantasia do not. The natural interpretation is that, in the absence of imagery, the impact of emotive language is reduced because imagery often mediates between the verbal description and the emotional response.”