(re-draft August 2016) The right hand upper window is leaning the wrong way, which is wonky for a start, but it’s not quite as wonky as it looks. It’s really identical to the window on the left and only seems to lean over more. What’s going on?
There’s something amiss with this dagger, for sure. For a start, the blade’s a bit short. More important, you can’t be sure just from the picture where the blade is pointing. That’s because one and the same perspective view can arise from more than one three-dimensional configuration, out there in the world. This dagger is […]
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 […]
Here’s a rather subtle effect. It’s a competition underway, when the Zollner illusion is seen embedded in a staircase. In the staircase lower left, where two of the long lines are either side of the outside edge of a step (in other words like lines a and b here, on the sides of a […]
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 […]
I’ve not been posting much because I’ve been struggling with a mammoth revision of my technical site on the Poggendorff illusion. But now that’s done, here’s a post on another Poggendorff puzzle. In earlier posts I’ve shown examples of competition between illusions, and included a demo of a paradox when the Poggendorff and Muller-Lyer […]
This is a stereo picture-pair, but you can see what’s happening here without having to view the images in 3D if you prefer. However, if you’ve not got the knack, and would like to practice on this post, here’s how. Hold up a pen about in the middle, between the two pictures, and about five […]
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 […]