Phenomenon	Figures	Description	References
Hollow-face illusion	1A	A concave mask is perceived as a convex face.	Gregory, 1997
Reversible figures	1B,C	The stimulus configuration allows for multiple interpretations. Within the category of reversible figures, a difference can be traced between figures whose reversibility is based on reference frame re-alignment, such as the Necker cube (1B, other instances are the Schröder Staircase and the Reversible Book) and on meaning reconstruction, such as the Wife/Mother-in-law ambiguous figure (1C, other instances are Rubin's vase/face and the duck/rabbit figure).	Long and Toppino, 2004
Binocular rivalry	1D	It occurs when two different images are shown simultaneously to the two eyes at a corresponding retinal location. Perception switches between the monocular inputs, although phenomena of mixed dominance are also possible (piecemeal rivalry).	Wheatstone, 1838; Levelt, 1968
Shape from shading	1E	Objects are perceived as concave or convex depending on whether the shading pattern is compatible with the scene being illuminated from above.	Ramachandran, 1988
Ambiguous point-light walker	1F	A human walker can be defined only by dots placed at the main joints: the dots configuration is immediately perceived as a walker as soon as it starts moving (i.e., it is an instance of structure-form-motion, see 1G). Bistable point-light walkers are compatible with two three-dimensional interpretations, dissimilar only for the depth order of the body parts: a point-light walker in frontal view can appear to face toward or away from the observer.	Vanrie et al., 2004; Manera et al., 2012
Ambiguous structure-from-motion	1G	The stimulus consists of a two-dimensional projection of a three-dimensional object (in this case a sphere), composed of dots laying on its imaginary surface: when motion information is added to the display, the stimulus is seen as a three-dimensional object and opposite directions of motion alternate in perception.	Metzger, 1935
Ambiguous apparent motion	1H,I	The repetitive presentation of single dots at a fixed frame rate induces the impression of motion: rather than perceiving static dots flashing at different positions on the screen, the viewer perceives them moving. The intermittent and subsequent presentation of four dots induces the subjective impression of vertical or horizontal motion in Figure 1H, whereas in Figure 1I the two dots may appear to translate horizontally or to expand and contract (loom and recede)	Wertheimer, 1912; Suzuki and Peterson, 2000; Kohler et al., 2008
Plaid motion	1J	When two drifting sinusoidal gratings are superimposed, the viewer may perceive the motion of the single semi-transparent gratings. Alternatively, what is perceived is a rigid structure (a plaid) drifting in a direction determined by the velocity and direction of the components.	Adelson and Movshon, 1982