The Science of Illusions (Paperback)

Ninio's discussion is focused mostly on optical illusions, with brief excursions into the auditory and tactile realms and a brave if short chapter on stage magic in which he shares his experience of catching a magician on television by slowing down a videotape, and thus exposing the loading of a bird done by quickness. But the popular cliché that "the hand is quicker than the eye" is also (professional magicians know) a form of distraction on the plane of explanation: only a very small minority of tricks are accomplished by quickness, the vast majority being the result of the distraction which magicians call "misdirection." And there are other illusion-steeped topics Ninio doesn't discuss: linear time (which Einstein called a persistent illusion), evolutionary epistemology (e.g., might not the truth ultimately be inimical to survival?), death, consciousness, the metaphoricity of "literal" language (e.g., "concrete"), free will (is it real?), and so on. In Hindu mythology the world is a game, lila, veil, or maya, of phenomena.

Ninio's narrowness allows him to go into detail about specific common misperceptions of geometrical figures, natural and urban landscapes and so on. But what might have happened if the narrator was not so trustworthy but unreliable, as in a novel, or if Ninio had attacked as illusions the egos of his readers with the same scientific thoroughness and creativity he musters in his analyses of optical illusions? I confess to being somewhat disappointed that multiple (and not always exquisitely translated) interpretations are given of minor (and sometimes, at least for me, not even visible) optical illusions when other possible illusions, grander and more foundational, such as those explored by neurology, were not even discussed. In an email from Ninio he blames this on trouble that occurred in transferring the artwork during translation. (Robert Frost defined poetry as that which gets lost in translation!)

And yet this elucidates the nature of illusion itself. Perhaps we can get glimpses of the whole but the fact remains that each and all of us-even all of us together as a parallel processing technologically connected scientific society-is only a part of the system we observe. The well-known mysteries of quantum physics hinge in part at least upon the necessity of reintroducing the observer who, for convenience's sake, had long before been removed (at least theoretically) from the system. Newer illusions, such as the mistaken apprehension of purpose, design, or life in thermodynamic systems, can also be understood as the result of the hidden operation of what has been observationally excluded. (So, too, the Monty Hall Paradox, if you know it, can be understood as an illusion of misplaced probabilities due to not accounting for information provided by the moderator assumed to be "outside" the frame of operation.)

"The illusion of always having reason"-Ninio's opening fragment, interpreted literally if not figuratively, intimates our perfectly human inability to keep illusion caged to the stage of entertainment or science. If we do not have reason, we lose the very means to detect sensory illusions. The senses, if they do not always tell the truth, require thought-itself a kind of supersense-to make sense. For it is our reason, our ratiocination or rationality-neurologically identified with the more recently evolved prefrontal cortex-that is responsible for sorting out conflicting perceptual cues. There is one world but many perceptions of it, reflecting the manifold beings which inhabit it. And yet evolutionary expediency allows us, no forces us (unless we are mad or drugged) to conceive of this world as whole despite being formed from data fragments. For example, you only have eyes in front of our head yet your conception of the space around you is not marked by a huge gap corresponding to the back of your head. Incomplete beings, we are "Procrustean" in our perception: we cannot help but fill in the blanks. Such endemic Procrusteanism may be instinctive, as in much perception or, as with Ninio here, consciously scientific in its explication of how perception works.

Ninio has indeed covered many sorts of illusions, including magic, but also such things we now take for granted as movies. It used to be that people shown a movie of a train coming at them would scurry out of its way, but we have seen enough movies by now to know that illusion for what it is. Ninio has concentrated on visual illusions because, of course, they can best be shown in a book. But also, as he points out, visual input is supreme, trusted more than other senses. People shown a film of someone saying "ga-ga" while the soundtrack says "ba-ba" will wind up hearing a hybrid "da-da" with their eyes open and "ba-ba" with their eyes closed. Everyone has had the experience of sitting in the old-style movie theater with one speaker behind the screen, and finding that the sound seemed to come from the location on the screen of whatever person or thing was shown making it. A ventriloquist, of course, easily makes visual cues of origin overcome auditory ones. The optical illusions here represent some of the old classics, as well as new ones, because new ones are being invented all the time. One of them was so strong that I believed there was a misprint when an explanation claimed that two parallelograms were the same size, so that I had to measure them, and even after that, I had to copy the page and cut the parallelograms out and compare them that way; they still do not look nearly equal. Other illusions here present obvious but invisible white shapes, or scintillating black spots that are not there, or even circuits that seem to have matter flowing around and around their printed images. This book is a wonderful funhouse.