Here’s another ambiguous severed head illusion. Is Koala thoughtfully holding up the severed head of Woven Person for inspection, or is it the other way round? You can see it both ways. For examples of this illusion in earlier posts, check out The Screams after Munch, the Monks, and the Mask/Skull illusion. (On that link this illusion may be at the top of the page, if so scroll down for the previous versions).
Does Mercury look like he’s rotating clockwise or anti-clockwise? That may depend on whether you look at the left hand figure, or the silhouette. That right hand silhouette figure can appear to rotate either way round. Some viewers find that it flips from clockwise to anti-clockwise spontaneously, but others may find it hard to make it flip from one rotation to the other at all. If it doesn’t change easily for you, try waiting till the outstretched arm is pointing top left, and then try to imagine the hand coming towards you (for an anti-clockwise turn) or moving away from you (for a clockwise one).
When the silhouette figure turns clockwise, it’s rotation mirrors the red figure. When it flips anti-clockwise, the two figures appear to go round the same way, but with the silhouette figure rotating half a turn out of sync with the red figure. I find the change fascinating, like the figures are doing some kind of old style dance, but two different ways.
The rotation of the right hand figure is ambiguous because in silhouette it presents exactly the same image whichever way it turns. Add the reflections and shadows of the red figure and it can only be going one way around.
I made the individual frames for the animation by taking successive still photos all around a reproduction of the original sculpture. (The original was made by Italian sculptor Giambologna just over four hundred years ago, and is in a museum called the Bargello in Florence, Italy).
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 particularly hard to interpret. It could be pointing downwards, with one edge of the blade longer than the other, like the blade in the top left pair of little images, of the dagger seen head on and from the side. Or the edges of the blade could be the same lengths, so we must have a steep perspective view of it leaning sideways, as in the top right hand pair of views. Look at the big image for a few moments, and I think you’ll be able to see it both ways.
Both configurations present exactly the same view in perspective, and both are about equally likely. (Well, maybe equally unlikely with this dagger would be nearer the mark). It’s a variant on an illusion which presents another clash of improbable alternatives – but one that tricks us into going for what may seem the least likely choice. We could call it the wonky flower box illusion.
Do the flower boxes in this scene look like they’re rectangular, if seen from above, but sloping downwards? But what if they stick straight ahead out from wall, like well-behaved flower boxes should, but are trapezoid, seen from above, (as diagrammed to the right)? Trouble is, once again the perspective view will be the same either way. What’s curious is that in this case, most observers opt for the downward sloping view of rectangular boxes, unlikely though that would be in the real world. Trapezoid plan boxes just seem too unlikely. It’s a version of the preference for right angles that leads us to accept incredible distortions of size in the Ames Room illusion. If technical stuff is for you, here’s a serious analysis of the window box effect (though with balconies rather than window boxes doing the weird sloping stuff). And if you just can’t get enough of that sort of thing, here’s a report of the same illusion in a church (also a bit on the technical side).
Here’s another example of the way illusion effects have been used in decorative art designs. (For examples in earlier posts, check out the category Illusions and Aesthetics, to the right). This mosaic is one of many from the Villa Romana del Casale, in the middle of Sicily, Southern Italy. Only the floors of this Roman villa are left. They are about 1700 years old, and are the largest expanses of mosaic floor surviving from the ancient classical mediterranean world.
The illusion comes in because different shapes in the design tend to pop out from one moment to the next. For example, in the pictures below I’ve selected out a star and a string of lozenges in the picture on the left, and then a hexagon shape in the picture on the right. Note that the hexagon interlocks with the star beside it with no gaps between them or overlaps, but when we select one, the other kind of vanishes, not only in these demo pictures, but even in the big picture at the start of the post. It’s a figure/ground effect, as in the faces/vase illusion, but without the dramatic light/dark contrast of faces and vase.
On the right, with apologies to Eduard Munch, I’d like to propose an improvement to his famous picture The Scream. In my version, the screamer really does have something to scream about: he’s holding up a duplicate of his own head for inspection. But which head is the one that’s attached to the body, and which is being held up for inspection? You can make it work both ways, with the upper head looking down on the lower, handheld one; or, as if the whole figure was leaning over to the right, with the lower head looking up at the handheld upper head. It’s another example of the effect in the Mask/Skull illusion, and in Improved artworks no. 1. I think I invented it, with a hint from Picasso (see the Mask/skull post). But I’ll be delighted if you prove me wrong by finding an older version.
No problem about the title for the improved version, it would have to be The Screams.
Here’s a rotating head illusion for Christmas. I’ve been giving talks about Christmas imagery, and sometimes use old fashioned transparencies. Recently I glanced at my slide of Santa upside down, and there was the face of the great Norwegian playwrite of a century ago, Henrik Ibsen. It’s an illusion in the tradition of the one I posted earlier, about two characters called Mr. and Mrs. Turner. (That post includes an animation). There are lots of other pictures of rotating heads by nineteenth century illusion artists.
It wouldn’t be easy to find two more different artefacts than these. On the left is a silk velvet embroidery made in Italy about five hundred and fifty years ago. On the right is a shield from Koave in Papua New Guinea, made in the last hundred years. Yet they both use exactly the same graphic device, a figure/ground effect.
Here’s another figure/ground effect. A saint becomes a balustrade! Almost any vertical figure whose profile is not too wiggly can be used for this illusion. Below is a different version of it. It’s a little more puzzling, because both saint and balusters, when seen as figure at the ends of the picture, have the same starry sky as background. That’s done by making sure that when saint or balusters are seen as background near the ends of the row, they blur into the same starry night sky.
Impossible shape illusion
This stag may look OK at first glance (well, you know, sort of…), but hang on, has he got three antlers, as at the top of the picture, or only two, as down by his ears? Following on from the last post, it’s another example of what happens when apertures or gaps in the visual scene – like the segment of starry night in the last post – become objects. But with the stag it’s even weirder, because the middle antler, for example, starts out at the top OK, but by the time it gets down to the stag’s head, it’s become background. Want to know more? Read on!
Here’s a historic artwork I reckon I’ve much improved. On the left you see it as has been for the last five hundred years or so, a Spanish (I think) wood carving, of a martyred saint, now in the Petit Palais museum in Paris. On the right I’ve turned it into an ambiguous image, in which it’s not clear which head belongs to the body, and which has been chopped off and is being held up for inspection – I think you’ll agree a far more poignant image. It’s an illusion in the style of the Mask/Skull illusion posted earlier.
Here’s a version of my adaptation with an evening sky:
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