Our brain exists in a state of “controlled hallucination”

Eventually, the vision scientists figured out what was going on. It wasn’t our computer screens or our eyes. It was the mental calculations the brain does when we see. Some people subconsciously deduced that the dress was exposed to direct light, and mentally subtracted the yellow from the image, so that they saw blue and black stripes. Others saw him as being in the shadows, dominated by bluish light. Their brains mentally subtracted the blue from the image and came up with a white and gold dress.

Not only does thought filter reality; he constructs it, inferring an external world from ambiguous inputs. In Be you, Anil Seth, a neuroscientist at the University of Sussex, explains how “the inner universe of subjective experience is related and can be explained in terms of the biological and physical processes that take place in the brain and the body”. He maintains that “the experiences of be you, or being me, emerge from how the brain predicts and controls the internal state of the body.

Prediction has become fashionable in academic circles in recent years. Seth and philosopher Andy Clark, a colleague in Sussex, refer to the predictions made by the brain as “Controlled hallucinations”. The idea is that the brain always builds models of the world to explain and predict incoming information; it updates these patterns when the prediction and experience we get from our sensory inputs diverge.

“Chairs are not red,” Seth writes, “just as they are not ugly, old-fashioned or trendy … When I look at a red chair, the redness I feel depends on both the properties of the chair and properties of my brain, and is the content of a set of perceptual predictions about how a specific type of surface reflects light.

Seth isn’t particularly interested in redness, or even color in general. Rather, his broader claim is that this same process applies to all of perception: “The entirety of perceptual experience is a neural fantasy that remains linked to the world through continuous making and reworking of better perceptual assumptions.” , controlled hallucinations. You could even say that we all hallucinate all the time. It’s just that when we agree on our hallucinations, that’s what we call reality.

Cognitive scientists often rely on atypical examples to understand what is really going on. Seth takes the reader through a fun litany of optical illusions and demonstrations, some quite familiar and others less so. Squares that are actually the same shade appear to be different; the spirals printed on paper seem to turn spontaneously; an obscure image turns out to be a woman kissing a horse; a face appears in a bathroom sink. Recreating the psychedelic powers of the mind in silicon, an artificial intelligence-fueled virtual reality setup he and his colleagues have created produces a Hunter Thompson-style menagerie of animal parts emerging piecemeal from others. artefacts in a plaza on the University of Sussex campus. This series of examples, in Seth’s account, “shakes the alluring but unnecessary intuition that consciousness is one thing – a great frightening mystery seeking a great frightening solution.” Seth’s point of view can be troubling to those who prefer to believe that things are as they appear to be: “Free will experiences are perceptions. The passage of time is a perception.

Seth is on relatively solid ground when he describes how the brain shapes experience, what philosophers call the “easy” problems of consciousness. They are only easy when compared to the “hard” problem: why does subjective experience exist as a characteristic of the universe. Here he clumsily advances, introducing the “real” problem, which is “to explain, predict and control the phenomenological properties of conscious experience”. It’s not clear how the real problem differs from easy problems, but somehow, he says, solving it will allow us to solve the difficult problem. It would be a good tip.

Where Seth recounts, for the most part, the experiences of people with typical brains struggling with atypical stimuli, including Come to our senses, Susan Barry, Emeritus Professor of Neurobiology at Mount Holyoke College, tells the story of two people who acquired new senses later than usual. Liam McCoy, who had been nearly blind since childhood, was able to see almost clearly after a series of surgeries at the age of 15. Zohra Damji was profoundly deaf until she received a cochlear implant at the unusually late age of 12. As Barry explains, Damji’s surgeon “told his aunt that if he had known how long and how deaf Zohra was, he would not have performed the operation. . Barry’s compassionate, nuanced and observant exhibition is informed by his own experience:

At forty-eight, I experienced a dramatic improvement in my vision, a change that repeatedly brought me moments of childish joy. Squinting from early childhood, I had seen the world mainly through one eye. Then, at mid-life, I learned, through a vision therapy program, to use my eyes together. With every glance, everything I saw took on a new look. I could see the volume and 3D shape of the empty space between things. Tree branches stretched out towards me; the lights were floating. A visit to the products section of the supermarket, with all its colors and 3D shapes, could plunge me into a kind of ecstasy.

Barry was overwhelmed with joy at her new abilities, which she describes as “seeing in a new way.” She is careful to point out how different it is from “seeing for the first time”. A person who has grown up with sight can catch a scene with just one glance. “But where we perceive a three-dimensional landscape filled with objects and people, a newly sighted adult sees a mishmash of lines and spots of color appear on a flat plane.” As McCoy described his experience walking up and down the stairs to Barry:

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