Optical Illusions » Size-constancy effects

Shepard’s tables – What’s up? (post no. 3)

david — Fri, 23 Oct 2009 17:35:31 +0000

This is a third look at the Shepard’s tables illusion. If you didn’t see the earlier posts, you might like to get up to speed on the illusion by scrolling down two posts to an animated demo. The two pairs of table-tops in these views are absolutely identical, and within each pair the two lozenge [...]

Shepard’s Tables – what’s up? (post no. 2)

david — Sun, 18 Oct 2009 10:47:34 +0000

The previous post presented an animation of Shepard’s Tables. If you didn’t see that, you might want to check it out first (scroll down to the previous post) to get the basics of the illusion. This new version of the illusion, with nested tables, follows the pattern: all eight of the lozenge shaped [...]

Shepard’s Tables – what’s up?

david — Wed, 14 Oct 2009 09:40:29 +0000

This is an animation of Shepard’s Tables, an illusion first published by Roger Shepard as Turning the Tables, (see his wonderful book Mind Sights, 1990, pages 48 and 127-8). The left hand lozenge-shaped table top seems to get longer and thinner as it rotates, but it’s an illusion. It [...]

Big Ben leaning over!

david — Tue, 07 Apr 2009 17:36:15 +0000

Does Big Ben look like it’s leaning over more in the right hand image than in the left hand one? It can take a double-take to spot that the two pictures are identical. I find it a fantastically strong illusion. It’s a demo of a new illusion found by Frederick Kingdom and colleagues (you’ll need to scroll down that [...]

Bressanelli and Massironi’s new illusion

david — Tue, 03 Feb 2009 11:19:47 +0000

Here’s another illusion only recently reported, by Daniella Bresanelli and Manfredo Massironi of the Universities of Padua and Verona. Look at the three shapes, and most people seem to see the bottom one as thinnest, judging width at right angles to the long edges, the middle one as a bit fatter, and the top one [...]

Lamp falling over!

david — Thu, 22 Jan 2009 12:41:52 +0000

Only joking, but the right hand picture does seem to show this old lamp near me leaning over more than it does in the left hand picture. But now check out the two pictures. They’re identical! It’s an illusion only recently reported by Frederick Kingdom and colleagues in McGill University (scroll down that link for [...]

Paradoxical Size Constancy

david — Fri, 12 Sep 2008 10:31:08 +0000

Size constancy is the term for our tendency to see distant objects as larger than they are. So the far end of a shape with parallel sides looks wider than the near end. (See the earlier post on The Wonky Window). It seems to be such a basic feature of vision that it can give [...]

The Wonky Window (size constancy)

david — Mon, 11 Aug 2008 01:34:05 +0000

Size-constancy effects make distant objects, especially in pictures, look larger. So in the table above, the back edge looks wider than the front edge. In fact, the sides of the table are strictly parallel. The fact that they don’t get closer together with distance, as we expect them to following the rules [...]