Trompe l’Oeuil and the Twins in the Ames Room

In the so-called Ames Room two twins move about and seem to the viewer to grow and shrink as they move. In certain sweet spots they appear of the same size (as in reality they are). The Ames Room is presented in the literature as a problem for theories of perception. Sometimes the effects on perception are explained in terms of dispositions of the brain to make everything neat.
According to Mark Johnston in the sweet spots two illusions collide to produce a third which so happens to be true—that the twins are of the same height. The first illusion is that the room is in any way like a normal room; the second one is that the twins grow and shrink by moving along the room; and the third that in particular places they seem of identical height.

Now, watch these two films on Youtube: the first, from the BBC-series The Mind’s Eye, gives you a nice impression of the illusions; the second shows the way the room apparently is built (a spoiler, so to speak). Try watching the films without sound (because the sounds will distract you from your own thoughts as they provide some explanation or other—neither one holds much promise, I think):
1. BBC
2. Ramachandran explanation (the simulation starts at 19 seconds).

Perception, Depiction, or neither?

First, is the Ames room a perceptual situation? We, the viewers, most certainly are not in the environment of the room. The simulation in the second film shows clearly how we are stood outside, and how we are supposed to look in through a small hole in one of the walls. That means that the situation is a trompe l’oeuil, requiring the viewer to be unnaturally fixed in a particular spot (because in any other spot the illusion would fail to show.) So our perception is non-egocentrical: if we move nothing changes in the thing viewed (Currie), which is very extraordinary, and hence it is fair to say that it is not at all clear what the Ames room tells us about perception. Would the twins take each other as growing and shrinking like we do, or would they, rather, be puzzled by what they see? (Has anyone cared to ask them?)

Why Fixation Inhibits Perception

It is not intuitively immediately clear that fixation inhibits perception, because, we want to think, if we see X that counts as perceiving X. My view here is that seeing merely counts as one aspect of perceiving—provided by abstracting from perception; but perception involves embodied agency (a spatio-temporal structure) and hence a veridical synchronicity of everything which enters the mind through he senses.

Holism about Perception

A holist theory of perception (which leads automatically, I argue elsewhere, to naive direct realism) involves someone who notices something visually to the effect of immediately attributing characteristics to be corroborated by many of the other so-called senses as well as by repeated and slightly altered vision (we see a chair and immediately expect it to look so-and-so from the back).

Depicted Trompe L’oeuil

The trompe l’oeuil is depicted, yes: we are watching a film of the trompe l’oeuil. The pictures clearly depict the twins as of different height: you can definitely measure the difference. Or, in different words: in Fig. 1.c. one can see how it is the camera who has made the right twin bigger than the left! We, the viewers of the picture are not fooled by the Ames room, but by its depiction. The picture clearly depicts the lines of floor and ceiling as symmetrical thereby enlarging the right girl, or diminishing the left girl.

a.	b.	c.
Figure 1. The Ames Room (BBC)

Perhaps the Ames room tells us something about depiction? I guess it does—like drawings by Maurits Escher do.

Pictures and Far-off Situations

The Ames room does seem to provide some insight in the similarity and the difference between what we see in a picture and what we see at large distances. First, egocentrical perception: if we see a table with books and a tea pot on it, we know we can grab either one of these objects or look behind them, and so on: if we move the interrelations between the objects change and thus we perceive depth, and we perceive how we might interfere in the world through our actions. Perception tells us all that; there is no need to actually do anything. Perception, however, does not provide us with that sort of information about the clouds above our heads. If we move the interrelations between the clouds do not change accordingly—they change all right, but not according to our movements. For all we know we might be watching a cloud movie.
(Cognitive science, and evolution theory might explain this by saying that we never developed perceptual means to anticipate on moving about in situations at such large distances, and why would we? We would first have to make sure to get there, and once there our perception will inform us in the right egocentrical manner. I am absolutely okay with that.)
Pictures do not present themselves as scenes where the perceivers might actually engage while all they do is put such interaction gradually out of reach on account of the distance. Instead, pictures present situations in a way which conceptually separates them from the perceiver—hence they do not fool us into some sort of illusion. Trompe l’oeuils however, do. They present us with situations which we may be fooled to believe to be able to enter into and interact in whilst demanding that we take up a place which puts us in the spot we are in when we look at the clouds: a spot disallowing us to actually move as perception dictates. Thus, the Ames room is neither a perception nor a picture (although it is presented to us now as depicted in a film).

a.	b.	c.
Figure 2. Construction of the Ames Room (Ramachandran)

Panorama Mesdag

The Panorama Mesdag (in Den Haag) provides a case where all three subjects are at stake at once: as a visitor you will be bodily aware of the railing and the sand just behind it; visually the sand can be seen to extend a certain distance, behind which the vista is taken over by pictures. The trompe l’oeuil is in this that it should be difficult to make out exactly where the real and the depicted sand meet, but little is done to fix the viewer because the situations are meant to be continuous with each other.

— Currie, Gregory. 1998. “The Aesthetics of Photography.” In Image and Mind, 72–74. Cambridge, New York: Cambridge University Press.
— Gibson, J.J. 1986. The Ecological Approach to Visual Perception. London, Hillsdale, N.J.: Lawrence Erlbaum Associates.
— Johnston, Mark. 2006. “The Function of Sensory Awareness.” In Perceptual Experience, edited by Tamar Szabó Gendler and John Hawthorne, 260–90. Oxford: Oxford University Press.
— McDowell, John. 1994. “Action, Meaning and the Self.” In Mind and World, 87–107. Cambridge, Mass and London, England: Harvard University Press.
____________. 1994. “The content of perceptual experience.” The Philosophical Quarterly 44:190–205.