How does that work?
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To be clear, there are big parts of this we don’t understand, and to make it more complicated, some people don’t create mental images.
But for those of us who do it’s all about how memory is formed. Memory isn’t stored like in a computer. When ever you experience things certain neurons in your brain sends signals to other neurons your brain. Memories form a bit like tracks form in a forest. When many people take the same path you’ll start to see a track form because the vegetation is trampled. When two neurons send a lot of signals to each other, their connection is strengthened. And neurons with strong connections send messages to each other more often, just like a well trodden path in a wood is more easy to follow.
When you are remembering something, your brain is simply walking down these familiar paths, i.e. the same neurons that are communicating when you are experiencing something are the neurons that communicate when you remember that thing. So when you remember something you’ve seen, it actually involves using the same neurons that were involved in actually seeing that thing.
The same thing happens when you imagine something because every memory doesn’t have a unique group of neurons, but rather certain patterns associated with certain concepts, images, sounds etc. Every time you have a memory where a football features, some of the same neurons will be involved in all those memories, and those neurons will also activate when you imagine a football without it being in a memory.
I am one of the people who cannot.
It’s about 50-50 in the population apparently, some people have strong visual imagery or an inner narrator accompanying their thoughts, others, like me, do not.
My head and thoughts operate silently and without image, though I have an excellent memory and pattern recognition ability.
Research points towards the idea that mental imagery is a separate system from regular memory. For example, rather than using the back of the brain where your eyes are connected and vision is processed, visual mental imagery has been observed to be tied to an area on the sides closer to the ears. As a result you can have people who are blind that can form mental images (assuming they weren’t blind from birth) as well as people who can see but can’t make mental images (which is called aphantasia).
Taken together this suggests that rather than recreating the exact sensation of looking at something, mental imagery works more on the concept level. In other words, if you look at an apple, your vision system can process the color red, a specifically round shape, the object’s relative size and a whole bunch of other small individual details that add up to you making the decision that “this is an apple”. Since we don’t see all of those color and shape areas activate when looking at the brain activity of someone who is making a mental image of that same apple, the current assumption is that the brain just reactivates “this is an apple” without all of the other detail. It’s more efficient so it makes sense. We also see the same type of thing in animals but it’s a pretty under-studied field.
For some reason the answers only seem to be talking about memories themselves, but I think you were curious about how you can actually “see” or “hear” what is not there. This is because the pathway from your memory neurons to your visual cortex is two way, not just one. Your brain sends the same signals that it once perceived when you remember something. This causes the sensation of “seeing” it again. The same is true the auditory system.
I realized very recently (30-40’s) that I cannot visualize. I don’t “see” things in my mind. I can think about what things or people look like, but I can’t truly “see” them. I never realized that other people could. On the flip side, I have bizarrely vivid dreams, that I remember every detail of, including smells. My only point is that the human brain is incredible, unique, and not even close to understood at this point.
The same way you are able to see normally. Many people confuse the eyes for digital cameras. Like the eyes record a video. But that’s not how the brain works. What you *see* is actually a real time generated 3D image your brain has created. Think of it as the difference between watching a YouTube video of someone playing a video game vs actually playing the game. The YouTube video will appear flat compared to playing the video game because the YouTube video is just a recording of a 3D image. Whereas the game is you seeing the 3D image being generated in real time.
When you think of it this way, your brain being able to generate separate images, and sounds is pretty expected and not all that extraordinary. I mean the brain already has the hardware to do it. You need that hardware to navigate the world and make senseof reality. It’s just the brain using the same hardware but relying on memory and instinct for image and sound generation rather then the real time data it’s getting from your eyes and ears.
What fascinates me about this is movies. Someone can build a whole world inside their head. They create characters, who move how they want, say what they want, and have back stories and motivations that we, the observer, have never experienced but somehow understand.
Then they convince other people to act it out in exchange for essentially goods and services in this world. That is captured on film and shown to us. Like, we can literally watch someone else’s dreams, if they’re good enough at this.
I don’t understand how anybody can achieve this! But I love movies and I’m so grateful for other worlds, and other people’s dreams
I can’t. When I was 25 years old I found out most people can actually see images and it blew my mind.
I have something called Aphantasia. Look it up, you’ll probably find it interesting.
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