The Rocking Line Illusion

Abstract

A new visual illusion is described in which a smoothly translating object appears to rock around its own centre during motion. This “rocking line” illusion (RLI) occurs when the object passes through contrast boundaries formed by static background elements. However, for it to appear, the spatial scale of the display must be adjusted appropriately. We provide an online demo where the effect can be experienced and relevant parameters manipulated.