The role of context in Müller-Lyer illusion: The case of negative Müller-Lyer illusion

The majority of optical illusions are the result of the specific context manipulation of the critical part of the stimuli. There are different examples of how context distorts figures in a way that they might seem different in size, shape, or shade. In the particular case of the Müller-Lyer (ML) illusion, the critical part of the stimulus is the central line (shaft), while the fins represent the context that can modify the perceived length of the central line. The fins usually come in two forms: inward (<>), also called arrowhead, and outward (><), featherhead fins. The length of the central shaft, i.e., the line is overestimated when it ends in outward fins, or is underestimated when it ends in inward fins. The example of the ML illusion can be seen in Figure 1. The ML illusion comes in several different variations. This illusion will also emerge if the double fins are replaced