What lessons is there in a visual illusion anyway?

Alex Tabarrok linked in one of the standard color illusions, and made this comment: If it is this easy to be mistaken about simple things it must be much easier to be mistaken about difficult things. From Geekolinks. To some consternation.
Big breath. Well. First of all yes. The pigment on the top and the bottom is the same. No, I haven’t double checked it. But, it is one of those things that it is not very hard to control, on a two-dimensional sheet, with either pigments or the computer. You can make sure they have exactly the same stimulus info (no matter what one tries to wriggle around to avoid this or try to make it out being a trick other than the trick that is actually there). The takehome message is that our perceptual apparatus (to be academic here) has not evolved to in some way match exactly what is out there (what is it that is out there anyway? It is a reflection of wavelengths that we happen to be able to see when in roughly normal ligt). Our perceptual apparatus has evolved in concert with our surroundings, and been tuned to pick up what is useful for our survival. We perceive what is out there, but it must be functional for us (whatever species we happen to be). Illusions like this are interesting, because it helps us unpack what these kinds of things may be (as psychologists). And, using them analogously (see – you are full of illusions. Things are not what they seem) is… fraught.
The capacities we have that makes it impossible to see the two colors as the same on that two-dimensional sheet (even if they are), are perfectly wonderful in our three-dimensional world – which is the world we inhabit, and which we have tuned our vision (and other senses) too. It also tends to be a world where light comes in overhead (Gigerenzer points this out, for example). It is a world where the wavelength sent back from surfaces may vary, even though the underlying color may be the same – but we perceive them as constant. (What color does your walls have? Do you notice the shifts in the corners, by the ceiling, between the shadows and the lights? Do you think of the underlying color as being different? It is – the reflection differs, but you don’t see that. This is called Color constancy. Learning to paint, I had a hard time teaching my eyes to see the shifts in the colors on what I knew was a uniform color – in order to render that on that two dimensional surface).
According to Gibson, what we process is invariances – and that may not be the pigment, or the wavelength sent back, but something that allows our brains to know what changes and what stays the same. The illusions – all on two dimensions – only work on two dimensions. You create those in three-dimensional real life, you are not fooled. You move too much. You have to photograph the 3 dim sculpture in order to preserve the illusion.
You could read my buddy Andrew Wilson’s ecological psychology account of this. He knows it way better than me.
A lot of this is also true of other illusions and biases that we have. (The best book on this, I think, is The Invisible Gorilla. I only quibble with their last illusion, but they have most of this down very well. I’m so contaminated by my studies that I don’t fall for a few of those). We may think that we pick up exactly what is out there, unbiased, but we don’t.
But should you despair? No. Like the color thing, a lot of these biases are heuristics, that work remarkably well in the world. Not all of the world (as complex as it is now), but in a lot of the world. Don’t take my word for it – read Gigerenzer, who spend a lot of time looking for this.
Kahneman, of course, focuses on our biases to catalog and understand them (and not so much on the heuristics that lead us right) – and he is also worth reading.
But I think the take home I would … take home from that illusion is. Well, that is for visual perception. It has an interesting explanation. We get fooled by it in two dimensions, because we don’t get fooled in three dimensions. In the right context, our perception works.
So, to understand illusions and biases, don’t go metaphorical, go domain specific. Yes, we have loads of biases. We do not perceive or judge the world as it kind of is. Because that does not serve our survival (unless we are scientists and weirdly interested in that thing because, well, it is awesome). We perceive and judge what is useful. Try to understand why it is useful. What does it buy us.
So, back to Alex’s first point here: Does this really illustrate that it is more difficult to be mistaken about complex things? I don’t really think this is a good metaphor for that. Yes, complex things can be much more easily misunderstood (but the picture is not misunderstood – just the understanding that in this variant, the pigments are the same, even though they don’t look the same. One could make a similar picture which would look very much like it, but where the pigments also would be different). It isn’t so much a misunderstanding, or even a misperception, as a trick playing with a feature of our perception that is very well tuned to our world – so I don’t think this is apt.
And, you know, some of Gigerenzer’s work suggests that simple heuristics can be very very good at dealing with very complex worlds. (And, it was kind of ironic that just the next day, Tyler Cowen linked in the “simple rules for a complex world” book. A very Gigerenzer/Gibsonian idea.)

About asehelene

... because if I'm in a room with a second person, I want to be reasonably sure I'm the crazier one.
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