The traditional view of understanding the working mechanism of visual perception goes back to the 16th century French philosopher Descartes. Descartes believes that the brain first constructs a mirror model of the external world, and then in the brain, we observe this like watching a movie According to this view, inverted glasses cause the internal mirror model to be inverted, and the brain generates visual perception based on this inverted mirror. However, more and more people are beginning to question this interpretation, and Degener is one of them. The visual phenomenon he experienced on the 30th day of the experiment led him to the opposite of Cartesian mirror theory. The most likely to press down is:. ['How visual perception works.', "Degener's experimental results.", 'How Inverted Glasses Work.', 'Flaws in Cartesian mirror theory.']