The Difficulty of Making Things Out

“I can think of no good reason to deny that a tilted coin could be seen as elliptical and flat with respect to the viewer. This would be tantamount to denying the possibility of illusion.” -John O’Dea “Art and Ambiguity: A Gestalt Shift Approach to Elusive Appearances” (2013)

In the concluding paragraph O’Dea writes:

“Constancy often fails; deep shadows can make surface colour perceptually unclear; at severe angles, shapes constancy disappears; size becomes harder to judge from more distant objects; and so on. Is perceptual experience illusory in these conditions?”

A denial of illusion might be too much to ask, but perhaps we could urge that the term be used with great caution. When things recede into the distance they do not gradually become illusory, they are simply harder to make out. We see less of the far side of the table than the near side. This isn't an illusion or an inaccuracy. It's a commonplace and unremarkable consequence of the spatial fall-off of sensory input. The further away something is, the less we see of it. The process is linear and gradual and leads eventually to the complete loss of input as an object recedes into the distance.

Illusion and Veridical Perception

"Perception comprises, by stipulation, veridical perception and illusion." - Alex Byrne (2009).

Philosophers often make a distinction between what they call "veridical perception", in which things are thought to be seen in ideal circumstances, and "non-veridical perception" in which they are not. Some philosophers go so far as to say that all non-veridical circumstances are illusory. Others are more circumspect and limit the attribution of illusion to what they claim are "undeniable" cases. Mike Martin of UCL believes that the famous Ames room, where one views a specially prepared space through a monocular peephole, is one of these undeniable examples. He writes: "Viewing with one eye through an aperture into an Ames room can lead to distorted judgements of size." This may seem an uncontentious claim, yet it is not difficult to show that it is mistaken. To invoke judgement, as Martin does, is to attribute the cause to a sophisticated capacity of inference that could not possibly have evolved to such an advanced state if it were so prone to "distortion." Seeing isn't a set of ongoing judgements. The gibbon swinging through the trees does not infer the position of the branches it grabs with such consummate skill. 

If we point a camera through the Ames peephole, the resultant image will not be a distorted judgement. Ask someone familiar with the Ames room to make a model of what they see and they would have no significant difficulty. There is no distorted judgement and no illusory perception, only one or more ways of exploiting what we see in relation to what we know. 

For some reason philosophers don't seem to have cottoned on to the fact that the Ames room is carefully constructed to force what we might call a "pictorial view" which is a way of representing things that visual artists have always striven to acquire and refine. Seeing the world in terms of pictures is something we have learnt to do over millennia. We have become so good at it that we have incorporated these skills into our language in extraordinarily sophisticated ways, ways that infants pick up with the near ease of a gibbon swinging through the trees. Perhaps one day in the not too distant future philosophers will come to the realisation that a description of an "illusory appearance" is not a distortion but rather an innovative way of representing what we see. Such capacities by no means threaten our grip on reality - they only secure it more steadfastly. We are skilful little monkeys, more skilful than our philosophers are prepared to admit.

"Consider the oar's looking bent in water. Could we say that the oar's appearance is an illusion? That seems natural. But if so, then presumably the look of things through a glass of water, which will be similarly distorted, is also an illusion. And if that, then also the look of things through a magnifying glass held appropriately close? Through a telescope? Through ordinary corrective lenses?" —Eric Schwitzgebel