We report a novel visual illusion, where a 2 × 2 two-colored checkerboard square rotating against an identical background appears to morph into a circle with a size change. This illusion can be categorized as a subtype of the breathing illusion (BI) based on its phenomenological characteristics. However, it also exhibits intriguing features that may offer new insights into BI's underlying mechanisms, not fully captured by existing displays.
Usui et al. (Thu,) studied this question.