Vision scientists discover why people literally don't see eye to eye

This clicked with me when I watched The Brain with David Eagleman [1] on BBC a little while ago. I've always know there is a disconnect between reality and what you interpret but the way he described it stuck. Note this is my layman's way of describing how I understand it.

Firstly your eyes are not connected directly to your "brain". You don't see what is in front of you.

Your eyes write a rough scan of elements of what is in front of you to a "frame buffer". Your brain looks at this "frame buffer" and interprets what it thinks you are seeing. At this stage it can fill in blanks and do all sorts of manipulations to make it look smooth and complete.

What can also happen is your brain can write to this "frame buffer", this is indistinguishable from the information the eyes have put there. This is pretty much how psychosis works - those monsters/spiders/people/objects seem as real as if they are there.

[1] https://www.bbc.co.uk/programmes/b06yjrdp

My father was a photographer and over the decades he worked with many other photographers in his darkroom (this was in the era of chemical photography). After several hundred occasions when he and another photographer were looking at a print under the color balancer, he realized they were literally seeing different colors. My father, who was scientifically inclined, eventually worked out the average variation, which I want to say was two clicks on the projector, but I’d need to check to find out what that actually meant in terms of frequencies. It’s a small variation, but it was certainly real. Remember, these were all professionals with years of skill at judging color.

I watched a program on PBS back in the mid 80's about San Fransisco and the Haight Asbury Free clinic.

They were speaking with a doctor about "acid casualties" LSD. What the doctor said was really interesting.

People who have flashbacks get scared thinking their brain is fried, and it's usually triggered by something visual. The patients have visual "abnormalities" and it scares them into thinking a new acid trip will start. In reality what LSD, Mushrooms, Peyote, etc. can do is strip away all the adaptations in the visual system. He said in most cultures that use psychedelics they usually talk about cleansing, or stripping away when using psychedelics, and with the visual system it's a true statement.

When he went on to say was that when we are born our visual system is like a blank downloadable computer, and as we grow, the visual part of our brain is making adaptations based on what it knows vs what is 'senses'. He said that due to small eye movements the sensing would jiggle, especially in our peripheral vision, but we learn the the world doesn't jiggle, so the visual system makes sure that stable items don't jiggle. Tons of adaptations take place, depending on our lives and experiences some of us have more adaptions than others.

Sometimes when taking psychedelics all those adaptations get stripped out, or only some get stripped out, leaving people with the untrained system, and that untrained system doesn't present things in the same way. Colors don't look the same, sometimes things in the peripheral vision jiggle or move, moving our heads quickly while quickly moving our eyes can cause 'trails'. All indications that our visual system has had some adaptations erased.

The doctor said that eventually over time things get usually restored to normal. However he said for colors, it's interesting because for people that grew up in a different area of the country and had their color perception set at that location, they sometimes find the when wipe out the adaptions and reset things the colors sometimes don't matched. Depending on where they grew up vs where the adaptations get reset the color of the sunlight can be different, and that will alert the color adaptation.

Relevant Ted talk: "Your brain hallucinates your conscious reality | Anil Set" https://m.youtube.com/watch?v=lyu7v7nWzfo

n=9 ...

https://royalsocietypublishing.org/doi/10.1098/rspb.2020.082...

The article and its associated paper did not really engage me. Perhaps I am missing something.

However, I was reminded of something that I learned when taking drama lessons as a teenager, and which I have used as a teacher. Our attention of an object (such as another human) oscillates from eye to eye. However, it is biased to one eye. Generally this is the one on the opposite site to our writing norm (i.e. left handed = right eyed). If you really want to hold a scene when being filmed, look unwaveringly out of the eye that is nearest the camera. It will feel unnatural, but look dam cool on the screen. Look carefully... you can see Laurence Olivier and others doing precisely this.

As a teacher I use it in class to hold attention. But it’s best effect is on the screen.

My understanding is that you only have a relatively small area in the center of your vision where you get a clear image. And so your eye moves back and forth so rapidly that you can't tell without slow motion, sort of scanning in the environment into a 3d map.

So maybe some of the variability is in that mapping circuitry.

Is there an expert who could explain what's novel here ?

The layman summary seems to imply specialists are surprised that people judge distance differently which seem crazy to me. I mean we have known for decades that vision is the result of a complex process involving different parts of the visual system and that people results on tasks involving mainly vision (and coordination admittedly) vary.

What's the surprising part here ?

> “We assume our perception is a perfect reflection of the physical world around us, but this study shows that each of us has a unique visual fingerprint,”

I don’t think anyone makes that assumption. I think most people know we don’t actually “see” the physical world, our eyes receive electrical signals from photons and our brain interprets those signals and for lack of a better word we hallucinate the physical world (in the form of the visual light spectrum).

By its very nature, from a common sense point of view photons don’t hit our eyes at the same time or the same angle; therefore, electric impulses will be different reflected Differently in our hallucinations. And even if 2 people had the same distance/angle, there are sometimes other issues differentiating our hallucinations, just one example being color blindness, where for various reasons one person hallucinates different colors than another based on the same electric impulses from photons. Even without color blindness this happens regularly (think of the blue/white dress vs black/gold viral photo a few years back)