Try to close your eyes and picture yourself on the coast, viewing a beach. Can you see it? The sun glittering on the water, the pale shade of sand, maybe a bluish umbrella tilted against the wind. How clear is that umbrella in your mind? Now imagine : what if there was nothing there at all. Not blankness, nor darkness. Just absence. Is it possible? To be aware it's there, to know you are thinking about something, but unable to give it any shape or color or form?

The fact that some people do not have the capacity to form mental imagery was first described in scientific literature back in the 1880s, yet the phenomenon was largely ignored for over a century. It seems to be a common assumption that our private mental worlds are all the same – rendered from the same palette of sounds, colors, and sensations. 

“How do we know if someone with aphantasia isn't describing the same experience as someone with mental imagery? Just in different terms?” 

For a long time, psychology and neuroscience made similar assumptions, presuming that, barring some significant malfunction, our inner experience is much the same from one person to the next. But in the early 2000s, researchers returned to the subject of mental imagery and began to challenge the idea that everyone's imagination worked in the same way. 

How does one objectively measure what's going on in someone else’s mind? 

It's a question that sits at the heart of consciousness itself. We can describe our inner worlds to each other, compare notes, use analogies; but we can never truly step inside another person's experience. A scene playing out in your head might be vivid, almost tangible. In mine, it might be a faint impression, or a concept with no image at all. How would we even know the difference?. In one study, published in Current Biology, provides early evidence that the brains of people with aphantasia can light up as if they were generating mental images in their primary visual cortex; the main part of the brain responsible for processing visual information. However, a new research imply that the signal “warps or stretches” before it is perceived consciously by the person with aphantasia, study co-author Pearson, a professor of psychology at the University of New South, suggests that people with aphantasia still generate visual activity in their brains, but the images may not reach conscious awareness. 

“people with aphantasia can see mental imagery when they dream” 

How this happens is likely explained by the contrasting ways the brain generates deliberate visualization versus dream imagery. Typically, conjuring a mental imagery involves multiple brain regions, and it is sometimes referred to as a top down – process; your conscious mind reaching down into memory, pulling up images, assembling them with intention. It's like building something from a blueprint. But dreaming works in reverse, as a bottom – up process, like deep automatic parts of your brain fire off spontaneously, sending signals upward, and your mind weaves them into scenes and stories involuntarily. One is constructed; the other simply happens. 

Is there a reason? Is it considered a condition? 

There is not a specific cause for this neurocognitive phenomenon. Could be either being born with it, possibly due to a natural genetic link, or acquiring it later in life due to events like PTSD, head injuries, strokes, or even certain illnesses. It may also be related to differences in brain connectivity, particularly in the occipital and hippocampus regions. The exact cause is not fully understood, and research is ongoing, but it is thought to result from an inability to create or be aware of mental images. While it's a condition, it is generally not viewed as a medical disorder or disability, but rather as another point on the multidimensional spectrum of human experience. And yet, in a field that often relies on studying damaged brains to shed light on the functioning of consciousness. 

Vocabulary : 

• occipital : the lobe is the seat of most of the brain’s visual cortex, allowing you to see and process stimuli from the external world and to assign meaning to and remember visual perceptions. Located just under the parietal lobe and above the temporal lobe, the occipital lobe is the brain's smallest lobe, but its functions are indispensable. 

• top – down processing : involves perceiving things based on your prior experiences and knowledge. In other words, you use what you already know to make sense of the new information you encounter. It refers to how our brain utilizes existing knowledge and expectations to interpret new sensory information.  

• blueprint : a detailed plan of how to do something; for example a blueprint for success 

• aphantasia : in few words; literally the absence of fantasy 

• psychopath : the lack of ability to establish meaningful personal relationships, extreme egocentricity, failure to learn from experience.