Binocular rivalry

thumb|330px|Triptych of the The Elevation of the Cross (Rubens)|Raising of the Cross, Rubens, 1610–11, Antwerp Cathedral A triptych ( ) is a work of art (usually a panel painting) that is divided into three sections, or three carved panels that are hinged together and can be folded shut or displayed open. It is therefore a type of polyptych, the term for all multi-panel works. The middle panel is typically the largest and flanked by two smaller related works, although there are triptychs of equal-sized panels. The form can also be used for pendant jewelry.

thumb|Stereoscopy with a classic stereoscope, showing the two lenses a person looks through to see a 3D image formed behind them thumb|Pocket stereoscope with original test image. Used by military to examine stereoscopic pairs of Aerial photography|aerial photographs. thumb|View of Boston, ; an early stereoscopic card for viewing a scene from nature thumb|Kaiserpanorama consists of a multi-station viewing apparatus and sets of stereo slides. Patented by A. Fuhrmann around 1890.

symmetry (something looking the same) under rotation

optical phenomenon

traditional motif showing three hares sharing ears