What Synesthesia Can Tell Us About Connections in the Brain
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- Опубліковано 7 вер 2024
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Find a space with total darkness and slowly move your hand from side to side in front of your face. What do you see?
If the answer is a shadowy shape moving past, you are probably not imagining things. With the help of computerized eye trackers, a new cognitive science study finds that at least 50 percent of people can see the movement of their own hand even in the absence of all light. (see how you can do the test yourself: • Seeing in the Dark )
"Seeing in total darkness? According to the current understanding of natural vision, that just doesn't happen," says Duje Tadin, a professor of brain and cognitive sciences at the University of Rochester who led the investigation. "But this research shows that our own movements transmit sensory signals that also can create real visual perceptions in the brain, even in the complete absence of optical input."
Through five separate experiments involving 129 individuals, the authors found that this eerie ability to see our hand in the dark suggests that our brain combines information from different senses to create our perceptions. The ability also "underscores that what we normally perceive of as sight is really as much a function of our brains as our eyes," says first author Kevin Dieter, a post-doctoral fellow in psychology at Vanderbilt University.
Tadin, Dieter, and their team from the University of Rochester and Vanderbilt University reported their findings online October 30 in Psychological Science, the flagship journal of the Association for Psychological Science.
Although seeing one's hand move in the dark may seem simple, the experimental challenge in this study was to measure objectively a perception that is, at its core, subjective. That hurdle at first stumped Tadin and his postdoctoral advisor at Vanderbilt Randolph Blake after they initially stumbled upon the puzzling observation in 2005. "While the phenomenon looked real to us, how could we determine if other people were really seeing their own moving hand rather than just telling us what they thought we wanted to hear?" asks Blake, the Centennial Professor of Psychology at Vanderbilt and a co-author on the paper.
Years later, Dieter, at the time a doctoral student working in Tadin's Rochester lab, helped devise several experiments to probe the sight-without-light mystery. Ultimately, participants were fitted with a computerized eye tracker in total darkness to confirm whether self-reported perceptions of movement lined up with objective measures.
In addition to testing typical subjects, the team also recruited people who experience a blending of their senses in daily life. Known as synesthetes, these individuals may, for example, see colors when they hear music or even taste sounds. This study focused on grapheme-color synesthetes, individuals who always see numbers or letters in specific colors.
Reports of the strength of visual images varied widely among participants, but synesthetes were strikingly better at not just seeing movement, but also experiencing clear visual form. As an extreme example in the eye tracking experiment, one synesthete exhibited near perfect smooth eye movement-95 percent accuracy-as she followed her hand in darkness. In other words, she could track her hand in total darkness as well as if the lights were on.
"You can't just imagine a target and get smooth eye movement," explains David Knill, a professor of brain and cognitive sciences at Rochester. "If there is no moving target, your eye movements will be noticeably jerky."
The link with synesthesia suggests that our human ability to see self-motion is based on neural connections between the senses, says Knill. "We know that sensory cross talk underlies synesthesia. But seeing color with numbers is probably just the tip of the iceberg; synesthesia may involve many areas of atypical brain processing."
Does that mean that most humans are preprogrammed to see themselves in the dark? Not likely, says Tadin. "Innate or experience? I'm pretty sure it's experience," he concludes. "Our brains are remarkably good at finding such reliable patterns. The brain is there to pick up patterns-visual, auditory, thinking, movement. And this is one association that is so highly repeatable that it is logical our brains picked up on it and exploited it."
Since i discovered that i had a visual type of synesthesia as a teen i started believing that thats a primitive origin of the belief in magic or priesthood in early humanity, since you literally see the world in a very different way to others because you have the wiring slightly different in your brain
I have multiple forms of Synaesthesia, and I love it.
It was definitely surprising that not everyone had the same experience - like the number 5 being Cobalt blue (Hex #0047AB or RGB 0, 71, 171) for example.
Or that dry, unused Earl Grey tea bags smell like a lush green tumbleweed, but once you add hot water, Earl Grey tea smells like an orange pyramid.
I mean, how weird is it to not have that, right?
I always wondered how come I could see my hand moving in the dark. This makes perfect sense.
I see coloured shapes when I hear sounds in the dark whether my eyes are open or closed. This has become a more regular even in adulthood when sharing a bed with my partner who suffers with breathing problems at night and when any of my children would cry at night etc. I now wonder if this is the real reason why I've always been a light sleeper and suffer terribly with insomnia.
It could be, you should get it checked out, at least then you will be able to understand it more.
I'm a synesthete and seeing the letters on the board, I see them diffrently gives me a headache ;P
Ha ha, the orange M was not correct was it? Clearly M is blue :)
I thought everyone could do the hand thing. I always know where my limbs are and stuff
That’s so cool
Bruh same I never questioned it either
I can see my hand with my eyes closed
Not see see it but I see it
Does that make sence?
- SwanCake - yeah that makes sense. Me too. Like a grey outline
I believe there is SOME level of universal consistency with synesthesa experiences. For example, I see the C-note as a red square. But truth is, love songs are consistantly being written in C major. There fore red. C is like Valentines' Day. In fact, the GREATEST love songs from Lionel Richie to Siouxsie & the Banshees (see "The Last Beat of my Heart") are in the key of C. Further, as far as geometry is concerned, there are 64 squares that make up single square chess board, and, amazingly, 64 herz frequency is a low C note (in A-432 Scientific Tuning. Not standardized A-440 pitch). Here on my uTube channel are my visual shapes to a Burt Bacharach song, who's colors follow what I call "Pitch Psychology": ua-cam.com/video/JjFMh1k9FHw/v-deo.html
I have tactile color synesthesia
explain
@@Cartermchickprobably some touch sensations come on color or is strongly associated with color. For instance, a cats fur might feel like brown, but a mirror surface is blue.
Me too
wait a second I can move my eyes back and forth without tracking anything.
Your eyes are tracking you. Run!
☺️🧐
When you're from running in the 90's