Photo-Realistic Scenes with Cast Shadows Show No Above/Below Search Asymmetries for Illumination Direction


Show simple item record Cunningham, Robert en_US Beck, Jacob en_US Mingolla, Ennio en_US 2011-11-14T19:07:58Z 2011-11-14T19:07:58Z 1998-12 en_US
dc.description.abstract Visual search is extended from the domain of polygonal figures presented on a uniform field to photo-realistic scenes containing target objects in dense, naturalistic backgrounds. The target in a trial is a computer-rendered rock protruding in depth from a "wall" of rocks of roughly similar size but different shapes. Subjects responded "present" when one rock appeared closer than the rest, owing to occlusions or cast shadows, and "absent" when all rocks appeared to be at the same depth. Results showed that cast shadows can significantly decrease reaction times compared to scenes with no cast shadows, in which the target was revealed only by occlusions of rocks behind it. A control experiment showed that cast shadows can be utilized even for displays involving rocks of several achromatic surface colors (dark through light), in which the shadow cast by the target rock was not the darkest region in the scene. Finally, in contrast with reports of experiments by others involving polygonal figures, we found no evidence for an effect of illumination direction (above vs. below) on search times. en_US
dc.description.sponsorship Office of Naval Research (N00014-94-1-0597, N00014-95-1-0409) en_US
dc.language.iso en_US en_US
dc.publisher Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems en_US
dc.relation.ispartofseries BUCAS/CNS Technical Reports; BUCAS/CNS-TR-1998-034 en_US
dc.rights Copyright 1998 Boston University. Permission to copy without fee all or part of this material is granted provided that: 1. The copies are not made or distributed for direct commercial advantage; 2. the report title, author, document number, and release date appear, and notice is given that copying is by permission of BOSTON UNIVERSITY TRUSTEES. To copy otherwise, or to republish, requires a fee and / or special permission. en_US
dc.subject Visual search en_US
dc.subject Shading en_US
dc.subject Shadows en_US
dc.subject Cast shadows en_US
dc.subject Illumination direction en_US
dc.subject Photo-realistic rendering en_US
dc.subject Naturalistic scene en_US
dc.subject Search asymetries en_US
dc.title Photo-Realistic Scenes with Cast Shadows Show No Above/Below Search Asymmetries for Illumination Direction en_US
dc.type Technical Report en_US
dc.rights.holder Boston University Trustees en_US

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