5-MeO-DMT sometimes cancels the Ebbinghaus illusion

Psychedelics produce all sorts of visual distortions: from breathing walls and geometric patterns to complex visual landscapes populated by full-blown entities. Sometimes people claim to see the Truth on them — but it’s typically spiritual, emotional or personal truth. But can psychedelics make you see the world more clearly in the most literal sense? Amid the sea of visual distortions they produce, might some patterns be perceived more clearly than they are in our normal, sober waking state? At least sometimes, the answer appears to be yes . On 5-MeO-DMT, a powerful psychedelic, I experienced a near-complete cancellation of the Ebbinghaus illusion. The Ebbinghaus Illusion The two orange circles above are physically the same size, but the surrounding grey circles make the one on the right appear larger. This illusion was discovered by German psychologist Hermann Ebbinghaus (1850–1909) and popularised by Edward B. Titchener in a 1901 textbook on experimental psychology . Different people perceive the illusion to different degrees. To me, the circle on the right looks about 10–20% larger, depending on my distance from the screen and the size at which the illusion is displayed. I measured my own susceptibility using an app I vibe-coded with GPT-5.6 Sol : I dragged a slider until the two circles appeared equal in size. Qualia Research Institute’s research retreat In May and June 2026, I attended the Qualia Research Institute ’s research retreat in Tepoztlan, Mexico. Over eight w…