Perception And Reality
Do we see reality as it is? The fact that we are subject to perceptual illusion leads some thinkers to assert that we don’t. Instead, we see (or taste or feel, etc.) an illusion concocted by our brains. Donald Hoffman, Professor of Cognitive Science at the University of California at Irvine and a respected researcher, is a popularizer of this view. A couple of recent videos, one on the Science Channel,(1) and another on TED,(2) are entertaining expositions of his thesis that our experience is misleading.
Take this picture, for instance, one of many on his website:
The figure on the left contains various grey patches. Two of them, corresponding to A and B in the figure on the right, appear to be different but are actually identical greys; a photometer would find them to be the same. Hoffman takes this as evidence that the cognitive aspect of our perception (he calls it “visual intelligence”) constructs the greys that we perceive.(3)
The idea that the world we encounter in our everyday experience is not the real world is not new. Ancient Indian philosophy speaks of the world as Maya, illusion, which conceals the true nature of reality.(4) Plato likens us to prisoners in a cave and likens the things we experience to shadows thrown on a wall. The philosopher is one who breaks his (or her) chains and ventures out into the real world to perceive reality truly.(5) Kant said that things in themselves are unknowable; all we know through our senses is the world of phenomena.(6)
What Hoffman brings to the table is not only a wealth of experimental evidence but a plausible account of how we got this way. His thesis is that our perceptual apparatus is wired evolutionarily, not to perceive reality accurately, but to enhance our genetic fitness. What counts is not how well we see reality as it is, but how well what we see helped our ancestors stay alive long enough to mate and have children. And what we see is shaped by “tricks and hacks,” as he says(7), not accuracy.
This account is not merely a “just-so” story.(8) Hoffman has conducted some mathematically rigorous computer simulations that show that creatures that employ strategies tuned to utility outcompete those that employ strategies tuned to objective reality.
Here is a simplified version. You construct a series of simulated habitats, each of which has some quantity of food and water. Then you construct two creatures that will look at the habitats and choose one to occupy. One creature, the truth seeker, looks at the exact quantities of both food and water; it has an accurate perception of reality. Another creature, the simple hacker, just looks for the greatest amount of food and ignores water; it uses a trick, not a fully accurate perception. The truth seeker takes more time and energy to gather its information and make a choice than the simple hacker. The simulation repeatedly pits the two creatures against each other in a variety of habitats. It turns out that the simple hacker occupies the better habitats more quickly than the truth seeker. In other words, it outcompetes the truth seeker. Accurate perception of reality turns out not to be an optimal strategy.(9)
Hoffman and his colleagues have performed many far more complex simulations, pitting not just these two strategies against each other but yet another as well. The truth seeker embodies what they call a naive realist strategy; its perceptions fully match what really exists. The simple hacker embodies a critical realist strategy; its perceptions are limited but still reflect some truth about reality. Both are homomorphic to reality; that is, both have the same shape or structure as reality. The critical realist strategy is just less finely grained than the naive realist one. Hoffman proposes yet a third strategy, which he calls the interface strategy, in which perceptions are not homomorphic to reality. In the simulations, the interface strategy outperforms both of the others. Hoffman and his colleagues conclude that “natural selection does not always favor naive realism or critical realism. … In many scenarios only the interface strategy survives.”(10) In other words, it is entirely possible that our perceptions bear no resemblance to reality at all! (To be clear, Hoffman does not say that the interface strategy always or necessarily wins, only that it can. And that a lot more research is needed.)
So the claim, supported by some evidence, is that it is possible that our perceptions bear no resemblance to reality at all. But Hoffman, in his popular lecture, goes further. He claims that it is not just a possibility but a fact that they bear no resemblance. He says, “There’s something that exists when you don’t look, but it’s not spacetime and physical objects.”(11) And “When I have a perceptual experience that I describe as a red tomato, I am interacting with reality, but that reality is not a red tomato and is nothing like a red tomato.”(12)
Hoffman goes too far here. How can he possibly know that reality bears no resemblance to our perceptions? By his own admission, we have no contact with reality—what Kant calls the Ding an sich, the thing in itself—at all. So there is no way to make a comparison.
What we can compare is not experience with reality, but some experiences with others. Consider the visual illusion of patches of grey above. The reason we think our perception is illusory is that it doesn’t agree with what a photometer tells us. But we know what a photometer tells us only through our experience!
Try this: print this page and then cut out the two patches in question and place them side by side. In that position they will look the same. If you have a photometer, measure them, both in context and side by side. In all cases they will measure the same. You can go to the website of Edward A. Adelson, the originator of the illusion, to see more evidence for their sameness.(13)
There is a reason that we consider our experience of the photometer and our experience of the patches viewed side by side more veridical than our experience of the patches in context. It is simpler and more coherent to assume that the grey colors stay the same and our perception varies by context rather than that the colors actually change when the context changes. And the former assumption leads us to make more successful predictions.
What we take as physical reality is what Willard Van Orman Quine calls a “cultural posit.” His account is picturesque but informative:
As an empiricist I continue to think of the conceptual scheme of science as a tool, ultimately, for predicting future experience in the light of past experience. Physical objects are conceptually imported into the situation as convenient intermediaries—not by definition in terms of experience, but simply as irreducible posits comparable, epistemologically, to the gods of Homer. Let me interject that for my part I do, qua lay physicist, believe in physical objects and not in Homer’s gods; and I consider it a scientific error to believe otherwise. But in point of epistemological footing the physical objects and the gods differ only in degree and not in kind. Both sorts of entities enter our conception only as cultural posits. The myth of physical objects is epistemologically superior to most in that it has proved more efficacious than other myths as a device for working a manageable structure into the flux of experience.(14)
Similarly, the myth of reality as homomorphic, for the most part, to our experience is believable just because it works so well for us. Optical illusions reveal, not flaws in our perception, but how well our visual system is adapted to reality under standard conditions.(15)
(To be fair, Hoffman does have a more complete argument for his view of the relationship between experience and reality, which he calls “Conscious Realism,”(16) but a full discussion of that is a topic for another time.)
(1) Hoffman, “Can We Handle The Truth?”
(2) Hoffman, “Do we see reality as it is?”
(3) Hoffman, “Constructing Shades of Grey.”
(4) Wikipedia, “Maya (illusion).”
(5) Plato, The Republic, 514a–520a.
(6) Kemerling, “Kant: Experience and Reality.”
(7) Hoffman, “Do we see reality as it is?” time 11:45.
(8) Wikipedia, “Just-so story.”
(9) Mark, et. al., “Natural selection and veridical perceptions” pp. 505-506.
(10) Ibid., p. 513.
(11) Hoffman, “Do we see reality as it is?” time 16:22.
(12) Ibid., time 16:59.
(13) Adelson, “Checker Shadow Illusion.”
(14) Quine, “Two Dogmas of Empiricism,” p. 41.
(15) Bach, “Optical Illusions & Visual Phenomena.”
(16) Hoffman, “Conscious Realism and the Mind-Body Problem.”
Adelson, Edward H. “Checker Shadow Illusion.” Online publication http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html as of 19 July 2015.
Bach, Michael. “Optical Illusions & Visual Phenomena.” Online publication http://www.michaelbach.de/ot/ as of 19 July 2015.
Hoffman, Donald. “Can We Handle The Truth?” Online publication http://www.sciencechannel.com/tv-shows/through-the-wormhole/can-we-handle-the-truth-2/ as of 16 July 2015.
Hoffman, Donald D. “Conscious Realism and the Mind-Body Problem.” Mind & Matter Vol. 6(1), pp. 87–121. Online publication http://www.cogsci.uci.edu/~ddhoff/ConsciousRealism2.pdf as of 15 July 2015.
Hoffman, Donald. “Do we see reality as it is?” Online publication http://www.ted.com/talks/donald_hoffman_do_we_see_reality_as_it_is as of 10 July 2015.
Hoffman, Donald. “Constructing Shades of Grey.” Online publication http://www.cogsci.uci.edu/~ddhoff/adelson-illusion.html as of 16 July 2015.
Kemerling, Garth. “Kant: Experience and Reality.” Online publication http://www.philosophypages.com/hy/5g.htm as of 17 July 2015.
Mark, Justin T., Brian B. Marion, Donald D. Hoffman. “Natural selection and veridical perceptions.” Journal of Theoretical Biology #266 (2010), pp. 504-515. Online publication http://www.cogsci.uci.edu/~ddhoff/PerceptualEvolution.pdf as of 15 July 2015.
Plato. The Republic. In Plato: The Collected Dialogues. ed. Edith Hamilton and Huntington Cairns. New York: Pantheon Books, 1963.
Quine, W. V. “Two Dogmas of Empiricism.” The Philosophical Review, Vol. 60, No. 1 (Jan., 1951), pp. 20-43. Online publication https://webfiles.uci.edu/rsmead/PHIL330/Readings/Quine%20-%20Two%20Dogmas%20of%20Empiricism.pdf as of 31 March 2014.
Wikipedia. “Just-so story.” Online publication https://en.wikipedia.org/wiki/Just-so_story as of 17 July 2015.
Wikipedia. “Maya (illusion).” Online publication https://en.wikipedia.org/wiki/Maya_%28illusion%29 as of 17 July 2015.