Is your perception in reverse.
The brain’s process for creating mental images can be described as perception in reverse. When we perceive something in front of us, “we try to infer meaning from an image,” Nadine Dijkstra said. Electromagnetic waves enter our eyes, are translated into neural signals and then flow to the back of the brain, where they’re processed in the visual cortex. The information then flows forward toward the front of the brain into the memory or semantic regions — a pipeline that ends with us knowing we are looking at a cat or a cup of coffee.
“During imagination, we basically do the opposite,” Nadine Dijkstra said.
You start with knowing what you want to imagine, like a cat, and that information flows from the brain’s memory and semantic regions to the visual cortex, where the image is sketched. However, that’s a working model of visual imagination works; there’s still much that is not known about the process, such as where mental imagery begins and the role the visual cortex plays.
In reality, people’s subjective experiences vary dramatically, and it’s possible that there are different subsets of aphantasics neural explanations. Aphantasia and the opposite hyperphantasia, are on a continuum of vivid reality to an inability to mock up an image in their mind’s eye.
Neuroscientists say that aphantasia is not a disorder, it’s a different way of experiencing the world. Early studies suggested that differences in the connections between brain regions involved in vision, memory and decision-making could explain variations in people’s ability to form mental images. Many people with aphantasia dream in images and can recognize objects and faces, it seems likely that their minds store visual information that they can’t access voluntarily. It Is thought that about 1% to 4% of the general population lack the ability create a mental image while awake, this phenomenon is known as aphantasia.
Cornelia McCormick, a memory researcher at the University of Bonn in Germany, became curious. Knowing that mental images are intimately tied to memory, she wondered how the aphantasia people remember their own lives? She had her team
scan those with and without aphantasia while they recalled personal memories. They found that people with aphantasia tended to have weaker autobiographical memory and less activity in the hippocampus, which helps encode and retrieve such memories.
People with aphantasia can recognize objects and faces, and most can see images as they drift off to sleep and in their dreams. “They know what imagery is like from their dreams,” Adam Zeman said. But for some reason they have trouble accessing this visual information voluntarily. Zeman scanned the brains of volunteers as they rested in an fMRI machine. The scans suggested that, at rest, people with aphantasia have weaker connections between the brain’s higher level control center’s (the prefrontal cortex) and its lower-level perception centers (the visual cortex).
People with aphantasia report a wide variety of experiences. Some can “hear” in their minds, some can’t imagine visually or auditorily. Some have autobiographical memory, while many do not. Some have involuntary flashes of mental imagery. Most dream in images, but some do not. Most are born with aphantasia, although a small minority acquire it after an injury. It’s possible that people with aphantasia are less likely to have mental health problems marked by vivid mental images.
A lack of mental imagery doesn’t imply a lack of imagination. Adam Zeman has heard artists who self-describe as having aphantasia. Shomstein considers herself a creative and imaginative person. Successful people, including the novelist Mark Lawrence and software engineer Blake Ross, a co-creator of the Firefox web browser, have revealed they have aphantasia.
People with hyperphantasia see mental images that seem to them as real as the things they actually see. The images that hyperphantasics see aren’t the same as hallucinations because they know, at the time, that they’re not real. But that doesn’t mean they don’t feel real.
Some hyperphantasia’s even choose to live in their imagination, rather than in real life, Nadine Dijkstra said. “They sit down on the couch, they don’t leave their house, they don’t go to school, they don’t see friends, they don’t go to their work. They just imagine their whole life just the way they want it. Because for them, it feels as real as reality.”