Motion illusions as a psychophysical tool to investigate the visual system

Visual Illusion are non-invasive tool for investigating human brain mechanisms. Motion illusion refers to a perception of motion that is absent and/or different from what it is present in the physical stimulus. This chapter attempt to review the motion illusions, from the Gestalt observations to the modern neuroscience, dividing them in two main categories based on the type of their illusory motion: 1) the illusory motion observed without any type of motion in the stimulus and 2) the misperception of motion. Both types of illusions produced excellent examples of motion illusions that provided knowledge regarding the underlying visual system mechanisms.