From what...my friend say, this becomes evident with LSD.
They said it clearly amplified the internal part of some visual perception loop, in fairly straightforward ways. For example, intentionally trying to see something as it wasn't (like a shadow as a snake) would make it be seen that way (the shadow would take on a clear snake appearance, and even move a bit).
Some simple examples are all the face optical illusions (Thatcher, reverse mask, etc), that show our perception of a face is in no way direct.
I also have noticed a "ticking" effect at times. Maybe around 5-10Hz or so. Felt like some kind of global clock tick that was updating perception. Everything in between was interpolated. Course it could just be the drugs /shrug
They said it clearly amplified the internal part of some visual perception loop, in fairly straightforward ways. For example, intentionally trying to see something as it wasn't (like a shadow as a snake) would make it be seen that way (the shadow would take on a clear snake appearance, and even move a bit).
Some simple examples are all the face optical illusions (Thatcher, reverse mask, etc), that show our perception of a face is in no way direct.