Journal of Illusion

Motion-induced blindness occurs with a simple motion mask

Masataka Suzuki, Rikako Noda, Kazufumi Takahashi — Thu, 08 Feb 2024 07:54:42 -0800

We present a series of visual illusions, in which a stationary target composed of three dots can be erased in front of the viewer’s eyes by employing a limited number of stimuli moving near or behind the targeted dots. The simplicity of the configurations, including the target and moving stimuli, provides insights into the conditions that are necessary to achieve motion-induced blindness.

The bumpy circle illusion: apparent shape-distortion of filled circles placed on a checkered pattern

Shuichiro Taya, Masaya Ishikawa — Thu, 25 Jan 2024 04:26:20 -0800

A new visual illusion in which circles placed on the checkered-pattern background appear to be polygons is reported. In this article, we first demonstrated that the apparent distortion of circles in this ‘bumpy circle illusion (BCI)’ depends on the luminance difference between the circles and the components of the background. Then, with the aim of clarifying the mechanism that causes this phenomenon, the ‘low-pass filtering theory’ the ‘segmentation theory’, the ‘corner effect theory’, and the ‘completion theory’ were investigated. As a result, the low-pass filtering theory and the completion theory were rejected because they predicted the occurrence of the illusion in some modulated BCI figures that produced no illusion. The ‘segmentation theory’, which postulated that the same mechanism as in the curvature blindness illusion produces BCI, was also rejected because the same luminance assignment as for BCI image components does not produce the curvature blindness illusion. In addition, the curvature of lines appears to deform in the curvature blindness illusion, whereas the BCI does not produce an illusion of line circles, which also shows the difference between the two phenomena. The ‘corner effect theory’ is the most promising because it correctly predicts (1) how the apparent distortion of the circles appears and (2) the presence/absence of illusion with the outline circles depending on the checkerboard luminance alteration cycles inside and outside of the circles. However, the corner effect theory can only be justified if it is assumed that the strength of the effect is different depending on whether the checkered pattern is applied to the inside or outside of the circles. Whether such asymmetry does exist and the reason why the asymmetry occurs needs further investigation.

Double-mirror illusion: a new class of 3D illusion that creates anomalous U-turn and anomalous translation simultaneously

Kokichi Sugihara — Fri, 17 Nov 2023 07:44:15 -0800

This paper presents a new class of 3D optical illusion in which two types of mirror illusions occur simultaneously. The author previously reported the left–right reversal illusion, in which an object exchanges its left and right sides in a mirror, and the translation illusion, in which an object facing toward a mirror translates into the mirror instead of turning around. We will show that these two illusions can be created by a single object. If we place the object in front of two vertical mirrors meeting at the right angle, the object exchanges its left and right sides in one mirror and translates into the other mirror. As one variation of this double-mirror illusion, we create objects whose mirror reflections together with the original objects form a circular sequence oriented clockwise or counterclockwise uniformly. The mathematics behind these illusions and the origin of their robustness are also discussed.

Five types of anomalous perceptions created by the same mirror-reflection process

Kokichi Sugihara — Mon, 27 Mar 2023 09:13:13 -0700

The real world and its mirror image are plane symmetric to each other with respect to a mirror surface, but mirror images are often perceived differently due to optical illusions. This paper shows that there are at least five types of different illusory perceptions of mirror images of pictures, although they arise from the same optical process. In all five illusions, we place a 2D picture of a 3D object horizontally, and see its image reflected by a vertical mirror. In some cases, the left and the right are reversed (left-right reversal illusion), sometimes horizontal planes change their heights (height reversal illusion), sometimes a lying object rises up (lying-standing illusion), sometimes the object turns upside down as if having done a somersault (somersault illusion), and sometimes the object is replaced by a rather different object (replacement illusion). This paper examines why these illusions occur from geometrical and psychological points of view.