Autokinetic effect

The autokinetic effect is the illusion that a stationary point of light in darkness moves. It arises when visual reference points are absent and small eye movements go uncorrected.

Fixational eye movement: Small involuntary eye movements that occur even when gaze is held on a target. These movements can make a stationary light shift across the retina in darkness.
Alexander von Humboldt: A German naturalist and explorer whose studies ranged across geography, physics, and natural history. He described apparent movement of stars as an early account of the autokinetic effect.
Sherif's autokinetic experiment: Muzafer Sherif's study of how individual estimates of apparent light movement change in groups. It used the illusion to show convergence toward a group norm when objective motion was absent.
Induced motion: The illusion that a stationary object moves because its visual surroundings move. It reverses the key arrangement: moving surroundings create apparent motion, rather than darkness removing reference points.
Visual reference frame: A set of visual landmarks used to judge an object's position or movement. Darkness removes the landmarks that would normally distinguish eye movement from light movement.
Muzafer Sherif: A social psychologist known for experiments on social norms and intergroup relations. His 1930s studies used the effect to investigate how group judgments form.
Informational social influence: Influence that occurs when people use others' judgments as evidence about an uncertain situation. Participants could treat other estimates as information because the light's motion was ambiguous.
Phi phenomenon: An illusion of movement produced by rapidly alternating stationary lights. It creates apparent motion through changing stimuli, unlike the stationary light in the autokinetic effect.
Motion perception: The process by which the visual system detects and interprets movement. The illusion is a motion percept produced without movement of the light.
Autokinetic phenomenon experiments: Laboratory studies in which observers estimate the movement of a stationary light in darkness. These experiments made subjective apparent motion measurable across repeated trials.

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