Contrast-contrast asynchronies.

We introduce the "contrast-contrast asynchrony," a dynamic stimulus configuration that combines elements of the Shapiro contrast asynchrony with elements of the Chubb contrast-contrast illusion. In the contrast-contrast asynchrony, static textured fields surround two textured fields; one surround has high-contrast texture, and the other has low-contrast texture. The contrasts of the center fields modulate in phase with each other at 1 Hz, and as a consequence, the difference between the contrast of the centers and the contrast of the respective surround modulates in antiphase. Most observers report an antiphase appearance for high-contrast, fine-grained centers. These observers therefore respond to the difference between the center contrast and surround contrast. We also document three observers who do not see the asynchrony for high-contrast modulations of the center, suggesting possibly interesting individual differences.