Theories about changes in visual signal processing with LSD (and other psychedelics)

[Lambda188]

LSD had got me very curious about perception and sensation and how the mind works, and I've been finding it fascinating to study myself. I had a very interesting experience on my last trip (among many interesting experiences..), where I looked up at a smoke detector on my ceiling and saw the little light blink 6 to 7 times when it's supposed to blink once. Each time it blinked, it was a bit dimmer, in the same way that tracers fade behind your moving hand.
Since taking LSD, I've noticed a small amount of what I guess would be considered mild HPPD. I see tracers in my normal vision, not very intense ones, and only one trailing image. It was pretty annoying for a while, and even freaked me out that it wasn't going away, but after a week and some good nights' sleep, it mostly faded.
So I've been building a thing to test that flashing, a circuit that I can use to flash a little light with precise timing. Today, completely sober, I was flashing this light in 50 microsecond pulses at myself. I could distinctly see two flashes of the light, one following closely behind the first, less brightly. I called my roommate over (he has never used any sort of hallucinogen) to look at the light and he insisted he saw only one flash.
So, even though it seems I've either stopped noticing the HPPD tracers or mostly stopped experiencing them, I'm still seeing double after two weeks. I wonder if this will ever completely go away. I want to try and get some other people together who have taken LSD to try this experiment and see what they see. I can't really find anybody, though. (Any of you guys happen to be good with circuits willing to build a device of your own if I post the schematic, to try the same experiment on yourself?) I'm also going to build a new prototype that can get the pulse down to 5 microseconds, I think a shorter flash would make any afterimages more apparent. Someday I want to build a thing with red, green, blue, and yellow lights that all can be pulsed and arranged in a sequence with variable timing. A light-show machine for tripping.
I'm going to try and trip again this weekend, it will be interesting to try that experiment on myself at some point during the trip and see how many flashes I can see.

I think this shows something important about how the brain processes information, with some degree of feedback that sends the signal through multiple times where it's perceived more than once. I guess in normal perception, we can't directly "see" anything other than the first time it goes through the loop. Tripping causes the gain of that feedback to increase, so you can see the afterimages as pretty tracers, and now having taken LSD it becomes more apparent in normal perception.

I read this recently, it seems to agree with what I've been thinking:
http://images.tribe.net/tribe/upload/photo/7de/72c/7de72c3b-45b4-4d15-9e53-5008799399e7

What do you think about all this? I'd love to get somebody else's opinion.

 

[psy997]

Someday I want to build a thing with red, green, blue, and yellow lights that all can be pulsed and arranged in a sequence with variable timing. A light-show machine for tripping.

That is an amazing idea Lambda188, please do. I would like one myself

I think this shows something important about how the brain processes information, with some degree of feedback that sends the signal through multiple times where it's perceived more than once. I guess in normal perception, we can't directly "see" anything other than the first time it goes through the loop. Tripping causes the gain of that feedback to increase, so you can see the afterimages as pretty tracers, and now having taken LSD it becomes more apparent in normal perception.

I read this recently, it seems to agree with what I've been thinking:
image here

What do you think about all this? I'd love to get somebody else's opinion.

I don't think you can say the increased gain of the recurrently processed image is what causes afterimages. That's more of what's responsible for the insane detail in trees, grass, etc. I interpret it to mean that the brain receives it's "first image" which it scans and then outputs. The output is then re-entered into the circuit, along with whatever new stimuli there might be externally. What we're talking about here is recurrent excitation, meaning the output of that first scan is re-entered into the circuit over and over, much more so than regularly. So, when you have the first image and the entire sequence of new stimuli in one image, it creates a time lapse effect, aka tracing/trailing/blinking.

Under the Perceptual Distortions section I find Optic Frame Flanging and Fractally Recursive Flange quite interesting.

Can anyone further explain why the OFF causes the image to seem to rotate and twist?

The FRF seems to be exactly what happens when breaking through on a tryptamine. The recurrent excitation is so strong that it blocks out external stimuli and creates ever-changing images from that which was previously there.

Someone let me know if I'm misinterpreting any of this. Really intriguing stuff here, Lambda.

 

[hypnagogic]

I read this recently, it seems to agree with what I've been thinking:
http://images.tribe.net/tribe/upload/photo/7de/72c/7de72c3b-45b4-4d15-9e53-5008799399e7

Thanks for posting this. I was actually looking for a scientific explanation of what causes "fractal vision" after enjoying a combination of LSD, K and nitrous with some friends this past weekend.

 

[Sandozer]

I read this recently, it seems to agree with what I've been thinking:
http://images.tribe.net/tribe/upload/photo/7de/72c/7de72c3b-45b4-4d15-9e53-5008799399e7

What do you think about all this? I'd love to get somebody else's opinion.

James L. Kent is the guy who put together that poster for a MAPS convention a few years ago. It's basically an outline of concepts hypothesized by him in his book "Psychedelic Information Theory" which can be found as a PDF on google. It's a very interesting read and I highly recommend it! . I've also wanted to build some sort of light flashing/oscillating/color-moving device to study the visual effects of psychedelics. Cool idea on the blinky light. Welcome to BL Lambda.

 

[Lambda188]

Psy, what makes me think that increased gain causes the afterimages is detailed here in this diagram I drew (while tripping). It's not necessarily the gain of the image that's increased, it's the gain of the signal that's fed back. In this way, an increase in gain in one part of the system can be responsible for both the afterimages and the increased detail.
It's like putting a mic too close to a speaker. It feeds the signal back into the same amplifier, and that signal runs around the loop several times with some delay until it vanishes. Turn the feedback gain too high, by moving the mic close or increasing the gain of the amp, and it begins to fade more slowly and eventually will run away and oscillate. In theory, if the gain in my model is 0dB (or attenuation, as I've put it, is 0%), the circuit would become saturated and then that might be the point at which people have these unreal experiences of being transported to another plane of existence or something.
I've changed my thoughts a bit since I drew this. I now think that the delay of that feedback signal is longer than the delay of the actual signal.
If all goes according to plan I'm going to trip this saturday and I'll give this a real test then. I got the timing of my LED flashes down to 5 microseconds today, only problem is, it's not bright enough to see at such a short pulse. The shorter the pulse, the brighter the light needs to be for us to see it, it seems. It's interesting to watch, as I turn down the pulse length the light appears to become dimmer and dimmer, even though it's getting the same amount of power.

I'm going to check out that book, it sounds really interesting.

 

[Lambda188]

Thought some of you might be interested to see how my experiment went. I got the pulse of that light down to just two microseconds, and I changed it to a green light because our eyes are more sensitive to green light, which helped make it more easily visible.
I took about 200ug of acid (though I suspect it might have been a little bit stronger, because it was definitely more intense than my last 200ug trip). Ended up getting very little science done that day because the trees and birds were just so much more interesting, but I did get to play around with the flashing light and oscilloscope. When I turned on the circuit, it took me a while to figure out why it was broken and flashing more than it was supposed to, before I realized the the experiment had already been a success. I was seeing between 5 and 7 flashes of the light with each pulse. That wasn't completely constant, though, sometimes I'd only see it flash once. I could more reliably see more flashes if I looked at it out of the corner of my eye. I then turned the light so that it illuminated the wall, and cranked the brightness way up, then I played around with the clock speed and pulse width until I got it to the point where I was just seeing continuous blinking, despite that it only flashed about twice a second. I'm not sure what exactly the pulse width was, accurately operating an oscilloscope while tripping balls is exactly as hard as you'd imagine.
The scope was pretty useful to me, though. I set it to move a dot across the screen slowly, and I looked at it such that the screen filled my field of view and I held my eyes steady so that I could see the tracers move behind the dot. Looking at the grid I could approximate the distance behind the actual dot that the first afterimage appeared, and since I knew the sweep speed in miliseconds per centimeter, I could approximate the delay that the tracer afterimages lag behind the actual image. It came out to about 40 miliseconds. So it seems to me that's approximately the delay of that recurrent excitation. This delay didn't seem to change as the acid wore off, the afterimages just got less intense.
For those of you who haven't fucked with an oscilloscope on acid, I highly recommend it. In x-y mode, it's like an etch-a-sketch the way you can move a luminous dot around the screen watching the tracers behind it, really fun.
Later that night I also gave the blinking-light test to another friend of mine. Same conditions, total darkness, eyes adapted, pulse width about 10 microseconds. He said he could see three flashes out of the corner of his eye, and like my roommate, he'd never taken hallucinogens, though he is on SSRI medication. I want to get more people to try that on.
I really wanted to do some sort of hearing test with a click, to see if that same phenomenon also happens to our hearing. I guess it would sound like an echo. But I never got around to it.