The gap effect revisited: Slow changes in chromatic sensitivity as affected by luminance and chromatic borders

• Published in: Vision research (Oxford) Vol. 29; no. 6; pp. 717 - 729
• Main Author: Eskew, Rhea T.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1989; Elsevier Science
• Subjects: Adult; Biological and medical sciences; Color discrimination; Color Perception - physiology; Contour; Contrast Sensitivity - physiology; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Gap effect; Humans; Light; Luminance transitivity; Male; Middle Aged; Minimally distinct border; Photic Stimulation; Space life sciences; Vertebrates: nervous system and sense organs; Visual Perception - physiology; Color discrimination; Contour; Gap effect; Luminance transitivity; Minimally distinct border; Human; Eye; Sensitivity; Cone; Discrimination; Edge boundary; Vision; Color; Duration; Stimulus luminance
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/0042-6989(89)90034-5

Chromatic discrimination was studied with two half-fields that were either precisely juxtaposed or were separated by a narrow gap. When present, the gap was in some conditions filled with light isoluminant to the test fields. When the fields were juxtaposed, chromatic sensitivity declined with viewing duration. For a discrimination based solely on S cone activity, separating steadily-viewed fields by either a luminance or a purely chromatic gap caused similar enhancements of sensitivity. Neither type of gap had much effect when the fields were flashed. The results may be interpreted as showing that either a luminance or chromatic contour can spatially delimit the two half-fields, thus preventing a slow spatial integration from reducing the discriminability of the two sides of the field.