[{"id":710,"title":"Motion illusions arise from light source ambiguity","sha":"016e939e0e02aa0a110742c103ae503e","user_id":null,"state":"published","body":"Motion illusions such as [the rotating snakes illusion](https://journals.sagepub.com/doi/pdf/10.1068/p7706) or the [rotating cube illusion](https://twitter.com/jagarikin/status/1228122662368448512?s=09) remain unexplained. Recently, [Watanabe et al.](https://www.frontiersin.org/articles/10.3389/fpsyg.2018.00345/full?source=post_page-----dc303056171----------------------) showed that this category of illusions might be related to predictive coding.\r\nUnlike existing research focusing on 2D patterns, we propose that all motion illusions arise from predictions of the visual system resolving 3D light-and-shadow patterns perceived as ambiguous. All motion illusions can be understood as mimicking the shadow pattern caused by the relative motion of a light source and an object. \r\nFor example, the rotating snakes illusion in [Fig. 4c](https://journals.sagepub.com/doi/pdf/10.1068/p7706) can be understood as a 3D black and white wavy object seen from above,with grey shadows projected by a light source moving clockwise as to stay perpendicular to each wave crest (attachment: same illusion recreated with a real object).\r\nWithout the light source being explicitly visible,the pattern could be caused by (1) The light moving relatively to a static object or (2) the object moving in the opposite direction relatively to a static light source.\r\nWithout cues, in a statically lit environment, the visual system resolves the ambiguity by assuming the most likely scenario: the object must be moving, the light is not.","created_at":"2020-02-26T04:39:19.263Z","updated_at":"2020-04-15T18:43:55.808Z","zenodo_id":3709097,"doi":"https://doi.org/10.5281/zenodo.3709097","subject":null,"tags":["illusion","motion illusion","visual system","predictive coding"],"vote_count":1,"view_count":1,"score":1.1,"deleted":false,"muted":false,"tweeted":true,"attachment_file_name":"shadows.pdf","attachment_content_type":"application/pdf","attachment_file_size":528276,"attachment_updated_at":"2020-02-26T04:39:19.198Z"}]