Relative area and relative luminance combine to anchor surface lightness values.

Area of Science:

• Visual Perception
• Psychophysics
• Color Science

Background:

• Previous research suggests surrounds tend to appear white.
• Lightness perception is influenced by surrounding visual cues.
• Anchoring theory explains how visual elements influence perceived lightness.

Purpose of the Study:

• To investigate the role of relative luminance and area in lightness perception anchoring.
• To test the hypothesis that anchoring is solely controlled by relative luminance.
• To reconcile conflicting findings regarding area effects in lightness perception.

Main Methods:

• Participants viewed simple visual fields with two regions within opaque acrylic hemispheres.
• Both side-by-side and center/surround configurations were tested.
• The influence of relative luminance and area on perceived lightness was systematically varied.

Main Results:

• Anchoring is governed by relative luminance when the darker region's area is less than or equal to the lighter region's area.
• When the darker region's area exceeds the lighter region's area, relative area significantly influences perceived lightness.
• Increasing the darker region's area shifts its appearance towards white and the lighter region's appearance towards luminosity.

Conclusions:

• Lightness perception anchoring is a function of both relative luminance and relative area.
• A novel rule for area effects in lightness perception is identified, unifying previous findings.
• This framework provides a parsimonious explanation for diverse phenomena in brightness induction and lightness contrast.