title: Effect of spatial position on visual search for 3-D objects.
abstract: We examined whether the position of objects in external space affects the visual-search task associated with the tilt of 3-D objects. An array of cube-like objects was stereoscopically displayed at a distance of 4.5 m on a large screen 1.5 m above or below eye height. Subjects were required to detect a downward-tilted target among upward-tilted distractors or an upward-tilted target among downward-tilted distractors. When the stimuli consisted of shaded parallelepipeds whose upper/bottom faces were lighter than their side faces, the upward-tilted target was detected faster. This result was in accordance with the 'top-view assumption' reported in previous research. Displaying stimuli in the upper position degraded overall performance. However, when the shaded objects whose upper/bottom faces were darker than their side faces were displayed, the detection of a downward-tilted target became as efficient as that of an upward-tilted target only at the upper position. These results indicate that it is possible for the spatial position of the stimulus to promote the detection of a downward-tilted target when shading and perspective information are consistent with the viewing direction.
authors.affiliation: Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan. h.umemura@aist.go.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Umemura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watanabe
authors.forename: Katsunori
authors.initials: K
authors.lastname: Matsuoka
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001288:Attention; D003867:Depth Perception / Q000502:physiology*; D004192:Discrimination, Psychological; D005133:Eye Movements / Q000502:physiology*; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D011601:Psychophysics; D011930:Reaction Time