title: Interaction between luminance gratings and disparity gratings.
abstract: It was shown from geometry and photographic measurement that the shading pattern for a sinusoidal corrugated surface of frequency f approximates to a luminance-defined grating of frequency f, 2f or f + 2f in specific relative phase. It was confirmed that a luminance grating modifies the appearance of a suprathreshold stereoscopic corrugated surface, suggesting an interaction between shading and binocular disparity. Disparity thresholds for detecting random-dot, disparity-defined gratings of spatial frequency 0.2 or 0.4 c/deg were measured in the presence of luminance gratings of spatial frequency 0.4 c/deg with the same orientation. Phase-specific facilitation of disparity thresholds was greatest for a phase relationship inconsistent with shading of a corrugated surface, and was disrupted by positional uncertainty. The presence of texture-defined lines (which served to mark explicitly the successive spatial locations of salient depth features in the image) produced a similar pattern of facilitation, in the absence of shape-from-shading cues. The pattern of results indicates direct local interactions, including spatial cueing, rather than interaction of depth cues.
authors.affiliation: Department of Human Sciences, Brunel University, Uxbridge, Middlesex UB8 3PH, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Wright
authors.forename: Tim
authors.initials: T
authors.lastname: Ledgeway
mesh_terms: D000328:Adult; D015350:Contrast Sensitivity; D003867:Depth Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008029:Lighting; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D012684:Sensory Thresholds; D015357:Vision Disparity; D015348:Vision, Binocular / Q000502:physiology*