You are hallucinating right now to make sense of the world
...beyond our perceived thoughts of reality, there lies a world of 'perfect forms…Reality as we know it is just an imitation; a copy of these perfect forms -Plato believed that and if you read his Theory of Forms you'll have a few questions as well regarding our perception of the world.
What are hallucinations?
Hallucinations are sensations that appear real but are not elicited by anything in our external environment. They aren’t only visual – they can be sounds, smells, even experiences of touch.
Understanding what is happening in the brain during hallucinations reveals how we’re having them all the time and how they shape our perception of reality.
A bewildering and often very frightening experience in some mental illnesses is psychosis – a loss of contact with external reality. This often results in a difficulty in making sense of the world, which can appear threatening, intrusive and confusing. Psychosis is sometimes accompanied by drastic changes in perception, to the extent that people may see, feel, smell and taste things that are not actually there – so-called hallucinations. These hallucinations may be accompanied by beliefs that others find irrational and impossible to comprehend.
But a team of researchers based at Cardiff University and the University of Cambridge explore the idea that hallucinations arise due to an enhancement of our normal tendency to interpret the world around us by making use of prior knowledge and predictions.
In order to make sense of and interact with our physical and social environment, we need appropriate information about the world around us, for example the size or location of a nearby object. However, we have no direct access to this information and are forced to interpret potentially ambiguous and incomplete information from our senses. This challenge is overcome in the brain – for example in our visual system – by combining ambiguous sensory information with our prior knowledge of the environment to generate a robust and unambiguous representation of the world around us.
For example, when we enter our living room, we may have little difficulty discerning a fast-moving black shape as the cat, even though the visual input was little more than a blur that rapidly disappeared behind the sofa: the actual sensory input was minimal and our prior knowledge did all the creative work.
“Vision is a constructive process – in other words, our brain makes up the world that we ‘see’,” explains first author Dr Christoph Teufel from the School of Psychology at Cardiff University. “It fills in the blanks, ignoring the things that don’t quite fit, and presents to us an image of the world that has been edited and made to fit with what we expect.”
“Having a predictive brain is very useful – it makes us efficient and adept at creating a coherent picture of an ambiguous and complex world,” adds senior author Professor Paul Fletcher from the Department of Psychiatry at the University of Cambridge. “But it also means that we are not very far away from perceiving things that aren’t actually there, which is the definition of a hallucination."
Journal article:
http://www.pnas.org/content/112/43/13401.abstract
PR:
http://www.cam.ac.uk/research/news/how-hallucinations-emerge-from-trying-to-make-sense-of-an-ambiguous-world
Interesting reading via New Scientist - article behind a paywall
https://www.newscientist.com/article/mg23230980-400-you-are-hallucinating-right-now-to-make-sense-of-the-world/
Plato's Theory of Forms - Read & Learn
http://www.anselm.edu/homepage/dbanach/platform.htm
Image via Google Image search.
#neuroscience #hallucinations #perception #research #humanbrain #medicine
I was just listening to a radiolab episode about a guy who has blind spots following surgery to repair macular degeneration, and now sees colors in those spots that aren't colors the rest of us see. Likewise, I have a schizophrenic friend who sees the world in a fundamentally different way, with different colors and objects than what I see. But, in both cases their brains are doing the same thing the rest of ours are doing: making sense of the inputs they receive.
ReplyDeleteAs a chromesthet I can understand that John Bump
ReplyDeleteThat's sort of "wrong" question Kyle Macland , after all dreaming permits each and every one of us to be quietly and safely insane every night of our lives. ;)
ReplyDeleteAt the Seattle Aquarium we are learning how octopuses can perceive color while they don't have the cones (use for detecting colors) that humans do. Up to just a few months ago, we thought they could only see in black and white (grayscale).
ReplyDeleteI have two blind spots in my right eye. One is dead center where you normally focus on to see details. My brain try's to fill in the missing information but fails miserably. It's like looking at a word and two of the letters in the middle disappear and the surrounding letters are stitched together. Thankfully my brain doesn't need all the letters of the word to make sense of it all. But it sucks when you have to read an eye chart to pass your medical exams for USCG licensing.
Captain Jack: I was just reading about the color detection in rod-only animals a little while ago. That is a spectacular bit of optical shenanigans. (In a sense they do only see grayscale, but they manage to derive color from that through refraction.) Similarly I was reading about how the brain backfills missing visual data from retinal lacunae like yours. It's interesting to hear your description of what it feels like, rather than just seeing a description of the optics involved.
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