Colours your screen cannot display. After-images that last for weeks. Each issue, one phenomenon from the edge of vision — and a few minutes to experience it for yourself.
Issue № 1 · Chimerical Colours Three minutes
For the next three minutes, your visual system will manufacture two colours that no monitor can produce. The trick is in your eyes, not the page. You'll need to stare at one spot for thirty seconds at a time. Find a quiet moment.
Experiment № 1 — Self-Luminous Red
Hold your gaze for thirty seconds. When the screen changes, you will see a red brighter than the white it appears upon — a glow your monitor cannot produce.
Self-Luminous Red
The red you see on this white field is brighter than the white itself. Your cones, having been overwhelmed by cyan, are firing in protest — producing a colour more saturated than any pixel can be.
Experiment № 2 — Stygian Blue
When the field returns to black, look closely. You will see a blue darker than the black around it — a colour that should not be possible.
Stygian Blue
A blue that is somehow blacker than black. What you are seeing is not light at all — it is the absence of yellow, perceived as a colour by a visual system with no other way to interpret the signal.
Issue № 1 · Conclusion
Self-luminous red and stygian blue are chimerical colours — real perceptual phenomena first described by Hewitt Crane and Thomas Piantanida at SRI International in 1983. They cannot be displayed by any monitor. They cannot be photographed. They cannot be transmitted to anyone else. They live in the gap between your retina and your visual cortex, briefly, in the seconds after a strong stimulus is removed.
For thirty seconds, your eyes were a screen no one else can ever see.
After Crane & Piantanida (1983) · "On Seeing Reddish-Green and Yellowish-Blue"
Issue № 2 · The McCollough Effect Five minutes
Most after-images fade in seconds. The next experiment produces one that may persist for the rest of your day, and sometimes much longer. It is also more demanding: three minutes of looking at alternating patterns, without skipping. The reward is a small, semi-permanent change in the way you see the world.
A note · This experiment uses high-contrast red and green patterns. If you have a photosensitive condition or are prone to migraines, consider skipping.
Issue № 2 · Adaptation Phase
Let your eyes wander naturally across each pattern. Do not fix your gaze on a single point. Do not try to memorise the colours. The effect is automatic — your visual system is being recalibrated.
The McCollough Effect
The horizontal stripes carry a faint green wash. The vertical stripes, a faint pink. Neither colour is on your screen — your visual cortex has invented them, and bound them to the orientations you adapted to.
Issue № 2 · Conclusion
The McCollough effect was discovered by the psychologist Celeste McCollough in 1965, and it remains one of the strangest phenomena in vision science. Unlike most after-images, it is contingent: the colours appear only on stripes oriented as you adapted to. And unlike most after-images, it does not fade in seconds.
Researchers have measured the effect persisting for hours, days, weeks. The longest documented case lasted three and a half months. Look at a striped shirt this evening. A fence. A piano. A barcode. You may find that your visual system has not yet returned to neutral.
After McCollough (1965) · "Color adaptation of edge-detectors in the human visual system"