PURPOSE: Illusion of size and distance perception due to lack of sufficient reference points.
DESCRIPTION: The demonstrator opens and closes iris diaphragms in front of white lights out of phase with respect to each other (e. g. one is closed while the other is opened, and vice versa).
Observers experience the illusion that the white spots are moving toward and away from them, rather than changing in size. This one must be done in a room darkened as much as possible to remove visual reference points.
REFERENCES: (PIRA unknown.)
EQUIPMENT: Previously prepared illusion box.
SETUP TIME: None.
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