Most people cannot reliably identify which of two different-hued colors is lighter — 60% of answers are wrong

Albers reports that in repeated classroom tests asking students to identify which of two different-hued color samples is lighter (darker), approximately 60% of answers are wrong and only 40% are correct — even among advanced painting students, and the ratio remained constant across years. This is not a failure of attention but reflects the difficulty of comparing luminance across hue changes: the retina adjusts its sensitivity, and simultaneous contrast confounds the judgment. Photography also fails: black-and-white photography registers all lights lighter and all darks darker than the eye sees, flattening middle greys. The practical consequence is that perceived lightness relationships between different hues must be tested empirically, not assumed.

Examples

60% error rate persists even among art students. Testing method: use the after-image technique (Ch. V) to reveal which of two ambiguous colors is lighter by observing which appears lighter after rapid shift. In GLSL: use Luma calculation (0.299R+0.587G+0.114B) to compare luminance objectively.

Assessment

Collect five pairs of different-hued colors and rank them by lightness without any aids. Then measure their luminance values and compare. Explain any systematic errors in your ranking.