Contrast polarity, chromaticity, and stereoscopic depth modulate contextual interactions in vernier acuity.
Vernier alignment thresholds are strongly compromised when the vernier is embedded in an array of equal-length flanking lines. Here, we show that these contextual interactions can be diminished by giving the flanks the opposite contrast polarity, e.g., white flanks surrounding a black vernier. Similar results are obtained for red verniers and equiluminant green flanks and when vernier and flanks have different binocular disparity. Using special flank configurations, we can eliminate location uncertainty as an important factor for this kind of contextual interactions. We interpret these results as evidence that perceptual grouping of the vernier and the flanks plays an important role in the vernier threshold elevation caused by contextual flanks.
Sayim
Bilge
B
Laboratory of Psychophysics, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland. bilge.sayim@epfl.ch
Westheimer
Gerald
G
Herzog
Michael H
MH
D000328:Adult; D055253:Color Vision / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D003463:Cues; D003867:Depth Perception / Q000502:physiology*; D006801:Humans; D010775:Photic Stimulation / Q000379:methods; D012684:Sensory Thresholds; D015357:Vision Disparity / Q000502:physiology; D014785:Vision, Ocular; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult