We know that Patrick Hughes' three-dimensional works shift your visual perception as you move through the space around them. This visual trick is called reverspective, a portmanteau of 'reverse perspective' coined by Mr. Hughes himself. So we know what it looks like, and we like it. But we were curious about the particulars of the illusion, and snooped around Patrick's site to investigate. Here is a little excerpt that explains the phenomenon quite well:

What is Reverspective?
Reverspectives are three-dimensional paintings that when viewed from the front initially give the impression of viewing a painted flat surface that shows a perspective view. However as soon as the viewer moves their head even slightly the three dimensional surface that supports the perspective view accentuates the depth of the image and accelerates the shifting perspective far more than the brain normally allows. This provides a powerful and often disorienting impression of depth and movement. Patrick Hughes takes full advantage of this effect in his use of surrealist images that reinforce the altered reality of the viewer.
The illusion is made possible by painting the view in reverse to the relief of the surface, that is, the bits that stick furthest out from the painting are painted with the most distant part of the scene. This is where the term reverse perspective or Reverspective comes from. 

If hearing this in layman's terms is not good enough for some of you, there are also some scientific readings available on Patrick's website that explore the illusion of reverspective in greater detail.