Not fractals or like a kaleidoscope. I'm not sure I have the words to explain it in any understandable way, and I'm certain that I lack the skill to do it justice. Usually it starts as blots of colour/brightness, as well as gradients (both radial and linear), and some more exotic images. Then if I keep paying attention they'll start to morph into all sorts of different things. These can be abstract imagery (not entirely unlike a kaleidoscope I suppose), but more often the abstract imagery is just a backdrop or peripheral image. Where I'm looking I'll see the images morph into objects, people, locations, etc., and most strangely, concepts. I'm not sure how to explain that last bit, but sometimes in these visualizations I'll just see something that is very clearly a concept/idea itself. I don't have much control over what I see like this, unlike daydreaming where I have almost complete control, or sleep deprivation induced hallucinations where I have control proportional to how awake I am. What I can do is when I see something that I like and want to see more of, I can focus on it. This generally helps prevent it from morphing into something different, but it only works for so long as I can maintain a strong focus on it, so I inevitably lose my grasp on it after some time.
Typing this all out now I realize it sounds strange, and I haven't heard anyone else talk about this in particular. For reference I have low-grade synesthesia (among a whole host of mental abnormalities compared to my peers), my family has a history of mental illnesses, and I'm just about the most neurotic person I know. I have never used any illicit drugs (including marijuana, which is fortunately now legal in Canada). I've considered trying LSD or psilocybin, but I'm worried about having a bad trip. I have however experienced many sleep deprivation induced hallucinations, as well as several fever dreams, dissociative episodes, and panics attacks. I've been told by a trusted source that fever dreams can be somewhat similar to using psilocybin.
I've heard about that sort of thing be experienced through yoga/meditation (and have seen stuff myself on occasion), but who knows what our brains are doing in those states. Perhaps you're naturally inclined to be able to experience those sorts of things...
Typing this all out now I realize it sounds strange, and I haven't heard anyone else talk about this in particular. For reference I have low-grade synesthesia (among a whole host of mental abnormalities compared to my peers), my family has a history of mental illnesses, and I'm just about the most neurotic person I know. I have never used any illicit drugs (including marijuana, which is fortunately now legal in Canada). I've considered trying LSD or psilocybin, but I'm worried about having a bad trip. I have however experienced many sleep deprivation induced hallucinations, as well as several fever dreams, dissociative episodes, and panics attacks. I've been told by a trusted source that fever dreams can be somewhat similar to using psilocybin.