Cubistic lands

Sandro Bettella, Gianluca Campana, Clara Casco & Sergio Roncato

Università di Padova, Italy
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© 2009 Sandro Bettella, Gianluca Campana, Clara Casco & Sergio Roncato

A configuration of alternating dark and light gray shapes positioned in counterphase at the opposite side of a dividing line leads to distinct perceptual outcomes, depending on background luminance. With backgrounds of extreme luminance (black/white), the shapes appear independent and joining at the corner. Backgrounds of intermediate luminance unify the shapes into a surface appearing as “corrugated”, in which illuminance (shadows lines) and reflectance edges are distinguishable. A rotation of the shapes around the orthogonal axis produces either vertical or horizontal furrows on the corrugate surface, depending on which of their sides form, during rotation, the smoothest contour.

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Tube illusion

UCD Medical Center, USA;University of Freiburg, Germany;PositScience, USA;University of Sassari, Italy
Tube illusion

© 2009 Lothar Spillmann

Take a cardboard tube, such as from a kitchen paper role, and hold it close to your eye, while keeping the other eye open. Look at a bright wall. The disk-shaped area seen through the tube will appear strikingly brighter than the same surface area viewed by the other eye. The effect is reminiscent of a flashlight illuminating the area under consideration. The effect takes a few seconds to fully develop. It also works with a textured surface where it enhances not only the brightness and color, but also the detail.

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Skyscrapers and Clouds

Sandro Bettella, Clara Casco and Sergio Roncato

Università di Padova, Italy
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© 2008 Bettella, Casco & Roncato

Here is a novel illusion that everyone can experience when the jagged contours of skyscrapers appear against the cloudy sky: with the clouds still behind, the skyscrapers contours appear to bulge out and the effect magnifies when the clouds move.
Most illusory distortions of parallel lines disappear if contours are jagged, but not our new illusion: we experience the “Skyscrapers and clouds” illusion because the visual system relies on local luminance contrast to code local tilts and positions along the contour bordered by a thin outline.

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Clones and Donors Have Opposite Inclinations (in Vision)

Oronzo Parlangeli & Sergio Roncato

Università di Padova, Italy
Clones and Donors Have Opposite Inclinations (in vision)

(© 2006 Oronzo Parlangeli & Sergio Roncato)

Fig. 1 and Fig. 2 show the same inducing pattern.
However, if the blue lines in fig 1 are seen as donors, we can easily appreciate that when they give birth to two clones as in fig 2, these clones grow apart and they show a diametrically opposed inclination: convex lines become concave and concave lines becomes convex.
A clone for each donor is sufficient to produce the effect.

Read more about the illusion and possible explanations

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