Locus of the Stimulus to Visual Accommodation: Where in the World, or Where in the Eye.
NEW MEXICO STATE UNIV LAS CRUCES BEHAVIORAL ENGINEERING LAB
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In two experiments, observers judged the apparent size of a collimated disk of light a simulated moon projected just above the horizon a real and virtual scenes by means of a stimulus presentation device, the moon machine. As these judgments were registered, masks obscured various bands of the lower half of the visual field. Immediately following these judgments measurements of the observers visual accommodation were made using a laser optometer. Results showed a strong correlation between mean apparent size and mean accommodation shift. Major conclusions were 1 viewing a virtual collimated image of a real scene is not the same as viewing the real scene, 2 for natural real scenes the retinal locus of scenic texture is the primary determinant of apparent size, whereas for virtual images it has a more reliable effect on visual accommodation, and 3 whatever the relationship between apparant size and visual accommodation is, their mean correlation is in excess of 0.90. These findings agree well with, and extend, those of Iavecchia, Iavecchia, and Roscoe 1978 and Simonelli and Roscoe 1979. Author
- Anatomy and Physiology