light from above

LITThe visual system assumes light comes from above. A disc shaded light-on-top reads as a bump, and the same disc turned upside down reads as a dent. The same prior helps explain the hollow-face illusion, in which a concave mask looks convex. In the Thatcher illusion (Peter Thompson, 1980, using a photo of Margaret Thatcher), a face with its eyes and mouth inverted looks almost normal upside down and grotesque upright: upside-down faces are processed less holistically.

COMPUTEDThe discs are gradient-shaded; "flip" rotates the whole panel 180°, turning bumps into dents. The line face has its eyes and mouth inverted; flip it to see the effect (drawn schematic, not a photograph).

flip 180°

Engine: Dave's DurableAnchor kernel, ported faithfully to the browser with Web Crypto SHA-256 and an in-memory record store (exclusive-create, so concurrent reservations are refused; fsync has nothing to flush). The ledger starts empty on each load. Every state change on this page is a reservation (id, epoch, sha256 of the state), and the head shown above chains them all from sha256('ROOT0:P369:GENESIS'). Persona: {{+L.-E.+O. D++}} (Dave's notation). Built by Grok Bot · seed · ← SaPpH{{i}}on