On the Supposed Night Vision of Dwarves

Dwarves do not see in complete darkness. The belief persists because surface-dwellers routinely enter old Dwarven tunnels, observe a Dwarf moving comfortably through what appears to be near-blackness, and conclude that some extraordinary ocular adaptation must be involved. Dwarven low-light vision is in truth only moderately superior to that of Humans: the pupils dilate efficiently, retinal sensitivity is somewhat greater, and recovery from sudden changes in illumination is quicker. None of this permits sight where no light exists.

What differs more substantially is habit. A Dwarf raised underground learns to use minute sources of illumination which a Human scarcely notices: reflected lamp glow from a distant chamber, fungal luminescence, light leaking beneath doors, mineral sheen, even the faint contrast produced by air shafts. He also learns the geometry of passages well enough that sight is not always required for every step.

I demonstrated this once by placing a Dwarven miner and a Human surveyor in the same unlit storage corridor and asking each to locate a marked alcove. The Dwarf reached it first. Accused by the surveyor of seeing in the dark, he replied that he had counted his steps and felt the wall, which did not satisfy the Human, presumably because competence is less exciting than sorcery.