Visual completion of three-dimensional, chromatic, moving stimuli in humans.

We studied whether visual completion can be produced within three-dimensional (3-D), moving, chromatic objects. Rotating thin and thick discs with red sectors, forming the corners of Kanizsa triangle, were presented on a display. Observers also rotated a hand-held real thin Kanizsa triangle.

Neon colour spreading in three-dimensional illusory objects in humans.

We studied whether neon spreading can be induced within three-dimensional illusory triangles. Kanizsa triangles were induced by black pacman disks consisting of red sectors with curved sides. Viewing our stimuli monocularly produced two-dimensional illusory contours and surfaces as well as neon spreading in each figure.

Three-dimensionally slanted illusory contours capture stereopsis.

In stereo capture a stereogram of a crossed illusory figure pulls a texture bounded by the illusory contours to the same depth plane with the illusory figure. We investigated whether three-dimensionally curved and slanted illusory figures could capture a repeating background texture. According to results, stereoscopic capture was perceived when a disparate illusory contour was slanted provided that the period of the background texture was consistent with the three-dimensional geometry of the illusory surface.

Effects of spatial configuration and number of fixations on Kanizsa triangle detection.

Purpose: Illusory figures, created by the visual system between visualizing real objects, are probably caused by processes designed to segregate objects from background. Support ratio--that is, the ratio between the physically specified and total triangle side length--has been suggested to be the main spatial determinant for suprathreshold perception of a Kanizsa-type illusion. To test this scale invariance hypothesis at threshold, illusory figure perception was studied by determining the effects of inducer size and distance at various exposure durations and fixation strategies on the frequency of seeing (FoS) an illusory Kanizsa triangle.

Three-dimensional illusory objects produced by rotation in depth.

Rotation of a Kanizsa triangle in depth around its vertical axis causes a perception of a three-dimensional object with a flat, rigid illusory triangle between the inducing discs. When the inducing discs of a Kanizsa triangle were made thicker, the illusory triangle between the discs also became thicker. In the experiments both computer animation and real inducers made of plastic were used.

Spatial and temporal properties of illusory figures.

The best known example of illusory figures is the Kanizsa triangle consisting of three disks with a sector removed. The disks and sectors are arranged so that they form the corners of a triangle. Although the sides of the triangle are not physically present, they are clearly visible to the observer.