Abstract

Gilchrist’s¹ subjects saw a test paper as adjacent to either a paper in a distant brightly lit room or a second paper in a closer dimly lit room (the apparent depth of the test being determined by interposition cues). The test and two other papers were always retinally adjacent. Gilchrist reported that grey-scale matches to the test were strongly influenced by the apparently coplanar paper; the other noncoplanar paper had virtually no effect. We wondered what Gilchrist's subjects had matched: brightness or lightness. We accurately simulated the rooms (excluding shadows) on a high-quality monitor. Luminance ratios (unlike Gilchrist's) under each illuminant were natural, not exceeding 30:1. Lightness matches showed Gilchrist's effect but to a lesser degree whether depth was cued by interposition alone or by stereo in addition. Brightness matches showed no effect of perceived depth. Results were replicated with a method of adjustment.

© 1987 Optical Society of America