The Müller-Lyer figure and the fly.
In the Müller-Lyer illusion two horizontal line segments of equal length are perceived by humans as unequal. The gaze of a fly presented with Müller-Lyer figures corresponds to human eye movements and human (illusionary) evaluations of the segment lengths. It is suggested that a theory similar to the phenomenological theory which accounts for the fly's gaze may account for the human eye's movement during an observation of Müller-Lyer figures.
D000818:Animals; D004175:Diptera / Q000502:physiology*; D005133:Eye Movements; D009043:Motor Activity / Q000502:physiology; D012858:Size Perception / Q000502:physiology*