Anecdotally, when I experimented with these, that's basically how I felt - it was very reminiscent of my imagination when I was much younger. As I started studying neuroscience, especially in grad school (I specialized in attention and sensory systems), the filtration theory made even more sense because our brain works on a lot of things in this way, especially our senses. I was also interested in autism and there's a fascinating hypothesis that the sensory effects are from malfunctioning sensory filters.