David Souto

"The job of any sensory system is to create objects in the world out of the incoming proximal stimulus energy” (Perceptual Coherence by
Stephen Handel). 

Most of  the time objects are correctly recognized without effort, however artful arrangements can reveal the fact that many solutions can arise from the same projection on the retina (the "proximal stimulus energy"). The London artists Tim Noble and Sue Webster made quite an impressive demonstration of this principle by creating a huge gap between the projection and the object that generates it (cf. image below). Even if no different from ombromanie, the art of creating images from hand shadows, it remains impressive.

When the heap of garbage is illuminated from one side we see a couple back to back, where there should only be some accidental organization.
At first I thought of it as a rather pessimistic version of Plato's allegory of the cave. The intention was clearly different though. The rubbish was produced by the artists consumption, who are thus doubly reflected by it.

In a recent paper published in Trends in Cognitive Science, Alex Holcombe reminds us that the temporal limits of perception do not allow for instance to know whether at any moment all hooves of a galloping horse raise above the ground.

I found this hardly believable, however a painting of Gustave Courbet, exhibited at the Neue Pinakothek of Munich, indicates that this is the case. Even a careful observer - a figurative painter - can get it wrong. The painting shows a "bolting" horse with the four hooves above the ground, which apparently can never happen with the legs stretched. Courbet was a victim of the poor temporal resolution of his visual sense.

The first analysis of a galloping horse motion is due to Eadweard Muybridge, in 1877, at the end of Courbet's life. Actually it seems that he did it in part because it was a source of debate at the time (http://en.wikipedia.org/wiki/Muybridge).

This website features a detail of a Chuck Close portrait. You may not have noticed at first sight that the banner is part of a face. In this kind of woodcut portraits you only see the three-dimensional shape that is represented at some distance. From too close (no play of words there) the details become inconsistent with the assumptions that the visual system makes about what should be a shadow, according to the interpretation given by Patrick Cavanagh and John M. Kennedy in Science.