0158422 - PSU-E 20035054 RIV FR eng J - Journal Article
Šikl, Radovan
Size constancy in near and far visual space.
Perception. Roč. 32, - (2003), s. 82. ISSN 0301-0066. E-ISSN 1468-4233.
[European Conference on Visual Perception. Paříž, 31.08.2003-04.09.2003]
R&D Projects: GA ČR GP406/03/D224
Institutional research plan: CEZ:AV0Z7025918
Keywords : Depth perception ů size constancy
Subject RIV: AN - Psychology
Impact factor: 1.259, year: 2003

Binocular perceptual cues are commonly thought to be one of the most important optical sources of information necessary to achieve size constancy. What happens when we observe an object in the distance where the efficiency of these cues sharply drops? In order to test size constancy for different distances (from 2 meters to 10 meters), we conducted a relative size judgement experiment where two stimuli were presented to an observer at the same viewing distance, but in mutually different orientations. Observers binocularly viewed a stimulus defined by four red LEDs lying on the ground surface and their task was to match the lengths of two opposite intervals. Both intervals were crossed in the middle of their length, therefore, in the case of a correct answer, the four dots formed a rectangle. We have found that the influence of orientation is not constant across all viewing distances studied. Whereas the observers` judgements were independent of relative orientations in the distance of 2 meters, it became a critical factor as the distance of stimuli were increased. The accuracy and reliability of judgements in the farther distances linearly decreased with the increasing difference between orientations what indicates the determining role of retinal size information.
Permanent Link: http://hdl.handle.net/11104/0055859