Avoidance behaviour to light in the protozoa Tetrahymena. The effect of a gradual versus an abrupt boundary between dark and light.
D000222:Adaptation, Physiological; D000818:Animals; D001362:Avoidance Learning; D001522:Behavior, Animal; D008027:Light; D011603:Psychophysiology; D013768:Tetrahymena / Q000502:physiology*