Watanabe Illusion (2010)

<p dir="ltr"><b>Watanabe Illusion (2010)</b></p><p dir="ltr"><b>渡辺錯視（2010）</b></p><p dir="ltr">The “Watanabe illusion” (Watanabe, 2010) is a visual illusion in which observers underestimate the slope of a short line segment; in other words, it is a phenomenon in which the perceived orientation of the line segment is pulled toward the horizontal. The stimulus for this illusion consists of a circle containing a diagonal line in the lower-left corner and a horizontal rectangle with dots arranged at regular intervals along its right edge.</p><p dir="ltr">Although the line is designed so that its extension intersects with the topmost dot, observers consistently estimate the intersection point to be several dots lower, demonstrating a systematic underestimation of the slope.</p><p dir="ltr">There are several variations of the “Watanabe illusion.” One is an illustration featuring a circle placed in the lower left corner with a line segment drawn inside it.

The perceived direction of the line segment’s extension is shifted toward the horizontal line.</p><p dir="ltr">Another is an illusion featuring two eyes. The position of the pupils is perceived as shifted toward the horizontal line. Yet another is an illustration of a girl drawing a bow.