Color my world

Our ability to perceive color is, when you think about it, a peculiar thing.

First, there's the rather hackneyed question of whether we all see color the same way (exclusive, of course, of people who are colorblind).  The way the question is usually phrased goes something like, "How could we tell if when you look at something red, what you see what I call green, but you still call it red because that's what you've learned?"  In other words, if I were to take a look through your eyes and brain, would the colors of objects be the same as what I see?

The answer is: we can't know for sure.  Thus far there's no way for one person to perceive the world through another person's sensory organs and brain.  But the great likelihood is that we all see colors pretty similarly.  All of our visual receptors are put together the same way, as are the visual cortices in our brains.  To assume that even with this structural and functional similarity, each person is still perceiving colors differently, runs counter to Ockham's Razor -- so without any evidence, it seems like a pretty untenable position.

More interesting is the comparison between how we see the world and how other animals do.  Once again, we run up against the issue that we can't see through another's eyes, but at least here we're on more solid ground because we can see that different animals have differently structured eyes.  Dogs, for example, have retinas with a much higher density of rods (the structures that operate in dim light, but only see in shades of gray) and a much lower density of cones (the structures that operate in bright light, and are able to differentiate by wavelength -- i.e., see colors).  Dogs aren't completely colorblind -- their two types of cones peak in sensitivity in the blue and yellow regions of the spectrum -- but they're relatively insensitive to colors outside that.  (This explains why my dog, Guinness, routinely loses his bright orange tennis ball in the bright green lawn -- to me, it stands out from fifty meters away, but he'll walk right past it without seeing it.) 

Then, there are bees and butterflies, which have eyes sensitive not only in the ordinary visible light spectrum but in the infrared and ultraviolet regions, respectively.  There are flowers that look white to our eyes, but to a butterfly they're covered with streaks and spots -- ultraviolet-reflecting markings that advertising nectar to those who can see it. 

A flower of the plant Potentilla reptans, photographed in ultraviolet light.  To the human eye, the flower looks solid yellow -- this is what it might look like to a butterfly.  [Image licensed under the Creative Commons Wiedehopf20, Flower in UV light Potentilla reptans, CC BY-SA 4.0]

But the winner of the wildly complex vision contest is the mantis shrimp, which has sixteen different color receptors (contrasted with our paltry three), rendering them sensitive to gradations of color we aren't, as well as detecting ultraviolet and infrared light, and discerning the polarization angle of polarized light.  How the world looks to them is a matter of conjecture -- but it certainly must be a far brighter and more varied place than what we see.

The reason all this colorful stuff comes up is because of a paper that appeared last week in Proceedings of the National Academy of Sciences, called "What We Talk About When We Talk About Colors," by Colin Twomey, Gareth Roberts, David Brainard, and Joshua Plotkin of the University of Pennsylvania.  The researchers looked at how words describing different colors vary from language to language.  "The color-word problem is a classical one," Plotkin said, in an interview with Science Daily.  "How do you map the infinitude of colors to a discrete number of words?"

And, more central to this research: does everyone do it the same way?  If you showed me a series of gradations from pure blue to pure green, at what point to I switch from saying "this is blue" to saying "this is green" -- or do I call the intermediate shades by a third, discrete name?

What the researchers found was that across 130 different languages, humans tend to group and name colors the same way.  Further, if you give people tiles with varying shades of red and asked them to pick out "the reddest red," the results show remarkable consistency.

Another interesting result of the research was that the sensitivity of our eyes to color variation isn't the same from color to color; we are much better at picking out subtle variations in red, orange, and yellow than we are at seeing differences in (for example) different shades of brown.  The researchers believe this is due to a difference in what they call communicative need; since reds, oranges, and yellows are the colors of ripe fruit, we've evolved eyes that are most sensitive to variations in those colors.  "Fruits are a way for a plant to spread its seeds, hitching a ride with the animals that eat them," Twomey said.  "Fruit-producing plants likely evolved to stand out to these animals.  The relationship with the colors of ripe fruit tells us that communicative needs are likely related to the colors that stand out to us the most...  No one really cares about brownish greens, and pastels aren't super well represented in communicative needs."

So it seems like the great likelihood is that we all see the world pretty much the same way.  Well, all humans, at least.  What the world looks like to a dog, with their better dim-light vision and better motion detection, but far poorer color discrimination, can only be guessed at; and what colors a mantis shrimp sees is beyond the ability of most of us to imagine.

Study lead author Colin Twomey wonders whether the same techniques could be used to study other facets of sensory perception.  "This is something that could be carried to other systems where there is a need to divide up some cognitive space," he said, "whether it's sound, weight, temperature, or something else."

One I wonder about is the sense of taste.  We know that taste differs a great deal between different individuals, not only because everyone likes (and dislikes) particular flavors, and those preferences differ greatly; but there are some people called "supertasters" who are sensitive to minor variations in flavor that the rest of us don't even notice.  (I am most definitely not a supertaster; the joke in my family is that I have two taste buds, "thumbs up" and "thumbs down.")  The daughter of a friend of mine, for example, has amazingly sensitive taste buds, to the point that she can discern whether the coffee was brewed with filtered water or ordinary tap water.

Me, as long as it's brewed with water and not turpentine, I'm fine with it.

But that's all potential future research.  For now, we have a better idea of how each of us colors our world.  And despite our individual differences, the answer appears to be that what you're seeing and what I'm seeing look very much alike.  

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As someone who is both a scientist and a musician, I've been fascinated for many years with how our brains make sense of sounds.

Neuroscientist David Eagleman makes the point that our ears (and other sense organs) are like peripherals, with the brain as the central processing unit; all our brain has access to are the changes in voltage distribution in the neurons that plug into it, and those changes happen because of stimulating some sensory organ.  If that voltage change is blocked, or amplified, or goes to the wrong place, then that is what we experience.  In a very real way, your brain creates your world.

This week's Skeptophilia book-of-the-week looks specifically at how we generate a sonic landscape, from vibrations passing through the sound collecting devices in the ear that stimulate the hair cells in the cochlea, which then produce electrical impulses that are sent to the brain.  From that, we make sense of our acoustic world -- whether it's a symphony orchestra, a distant thunderstorm, a cat meowing, an explosion, or an airplane flying overhead.

In Of Sound Mind: How Our Brain Constructs a Meaningful Sonic World, neuroscientist Nina Kraus considers how this system works, how it produces the soundscape we live in... and what happens when it malfunctions.  This is a must-read for anyone who is a musician or who has a fascination with how our own bodies work -- or both.  Put it on your to-read list; you won't be disappointed.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Jumbo shrimp

After yesterday's rather humbling post about how easy it is to fool the human senses, today we get knocked down another peg or two with some new research showing our visual perception is beat hands down...

... by a species of shrimp.

You've probably heard the term refresh rate used in regards to computer monitors, but it also applies to our eyes.  The photoreceptors in your retina have to reset after firing, and during that time -- the refractory period -- the receptor cell is insensitive to further stimuli.  I recall finding out about this in my animal physiology class at the University of Washington thirty years ago, and finding out that human photoreceptors reset in about 1/60th of a second.  This is why the flicker in a fluorescent light is barely detectable to the human eye; it's driven by the oscillations of alternating current at a frequency of sixty hertz; and the fact that we have millions of photoreceptors, all out of phase with each other, smooths out the signal and makes it look like one continuous, evenly-bright light.

To a fly, however, which has a refresh rate double ours -- about 120 times per second -- a fluorescent light would look like a strobe, brightening and dimming every sixtieth of a second.

Must be really freakin' annoying.  Yet another reason I'm glad I'm not a fly.

But even they are not the fastest.  A paper in Biology Letters this week describes research into the visual systems of a species of snapping shrimp (Alpheus heterochaelis), which already is badass enough -- it snaps its claws together with such force that it creates a shock wave in the water, stunning its prey.  And this little marine crustacean has a refresh rate of 160 times per second.

So what looks like a blur of motion to other animals is visible as clear, discrete images moving across its field of vision.

Not only that, they have one of the widest ranges of sensitivity to light level known, functioning well with only 1 lux of incident light (the light intensity of late twilight) all the way up to 100,000 lux (direct, intense sunlight).

[Image licensed under the Creative Commons Rickard Zerpe, Snapping shrimp (Synalpheus sp.) (23806570264), CC BY-SA 2.0]

The snapping shrimp isn't the only amazing crustacean out there.  Its cousins, the mantis shrimps (Order Stomatopoda) don't just snap their claws and stun their prey, they actually punch the shit out of them.  They can accelerate their claws at the astonishing rate of 102,000 m/s^2, delivering a force of 1,500 Newtons (equivalent to the Earth's gravitational pull on a 150 kilogram mass).  Not only that, but they move their claws so quickly they overcome the cohesion of the water molecules as they pass through, creating vapor-filled bubbles (a process called cavitation) in their wake.  These bubbles then collapse with astounding force, delivering a second deadly shock wave to the unfortunate recipient.

No wonder the folks in the Caribbean have nicknamed the native species of mantis shrimp "the thumb-splitter."

But wild as that is, it's not why I brought up mantis shrimp.  They have the most sensitive color vision of any animal known.  Humans are (mostly) trichromats, having three functioning types of color receptor in our eyes.  Dogs are dichromats -- they have only two, which is why their color acuity is worse than ours.  A few lucky humans, and a great many bird species, are tetrachromats, having four kinds of color receptors.

Mantis shrimp have sixteen.  They can not only see in the ultraviolet region of the spectrum -- a range of light completely invisible to the human eye -- they can detect polarization angle, and even have sensors for detecting circular polarization, something that is thought to be unique in the animal kingdom.

Why they need this many different kinds of light receptors is unknown, although it probably has to do with predator-prey interactions -- finding lunch and avoiding being made into lunch.  With so many different strategies used by shallow tropical marine species to confound the eye -- shimmering scales, transparency, cryptic coloration, countershading -- having eyes that beat everyone else in sensitivity and range would be a pretty neat adaptation.

So that's yet another excursion into the weird world of sensory perception.  It never fails to fascinate me to think about what a different kind of animal's experience of the world must be like.  As philosopher Thomas Nagel pointed out, the only way to know what it's like to be a bat is to be a bat; all of our ideas of echolocation and flight and being nocturnal only gives us the answer to what it's like for a human to think about being a bat.

But even so, and all pondering about the mind/body problem aside, I can't help but wonder what the world looks like to a shrimp.

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I know I sometimes wax rhapsodic about books that really are the province only of true science geeks like myself, and fling around phrases like "a must-read" perhaps a little more liberally than I should.  But this week's Skeptophilia book recommendation of the week is really a must-read.

No, I mean it this time.

Kathryn Schulz's book Being Wrong: Adventures in the Margin of Error is something that everyone should read, because it points out the remarkable frailty of the human mind.  As wonderful as it is, we all (as Schulz puts it) "walk around in a comfortable little bubble of feeling like we're absolutely right about everything."  We accept that we're fallible, in a theoretical sense; yeah, we all make mistakes, blah blah blah.  But right now, right here, try to think of one think you might conceivably be wrong about.

Not as easy as it sounds.

She shocks the reader pretty much from the first chapter.  "What does it feel like to be wrong?" she asks.  Most of us would answer that it can be humiliating, horrifying, frightening, funny, revelatory, infuriating.  But she points out that these are actually answers to a different question: "what does it feel like to find out you're wrong?"

Actually, she tells us, being wrong doesn't feel like anything.  It feels exactly like being right.

Reading Schulz's book makes the reader profoundly aware of our own fallibility -- but it is far from a pessimistic book.  Error, Schulz says, is the window to discovery and the source of creativity.  It is only when we deny our capacity for error that the trouble starts -- when someone in power decides that (s)he is infallible.

Then we have big, big problems.

So right now, get this book.  I promise I won't say the same thing next week about some arcane tome describing the feeding habits of sea slugs.  You need to read Being Wrong.

Everyone does.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Color my world

Perception is such a mystery.

Neuroscientist David Eagleman, in his brilliant TED talk "Can We Create New Senses For Humans?", touches on this with a concept he calls the umwelt -- the slice of the objective reality we're aware of.  That differs from animal to animal -- as he points out, for dogs, the umwelt is all about smell; it's sound-related for echolocating bats; it consists of electrical field fluctuations for the black ghost knife-fish; and so on.  Eagleman says:

What this means is that our experience of reality is constrained by our biology.  And that goes against the common-sense notion that our eyes and our ears and our fingertips are just picking up the objective reality that's out there.  Instead, our brains are sampling just a little bit of the world...  Now, presumably, every animal assumes that its umwelt is the entire objective reality out there, because why would you ever stop to imagine that there's something beyond what we can sense?  Instead, what we all do is that we accept reality as it's presented to us. 

What never ceases to amaze me is that even the parts of the human umwelt most of us are pretty good at picking up on are still made largely of faulty and incomplete information.  Our brains have evolved to fill in the gaps in what we see and hear -- so your perception of the world is built of what you're actually sensing of the real world, and what your brain assumes is there and fills in for you.  (That it sometimes does this incorrectly is the basis of a lot of optical illusions.)

If you need further evidence that you're seeing some bits of reality but otherwise just kind of making shit up, consider a paper published this week in Proceedings of the National Academy of Sciences, by Michael Cohen (of Amherst College) and Thomas Botch and Caroline Robertson (of Dartmouth University).  In "The Limits of Color Awareness During Active, Real-World Vision," Cohen, Botch, and Robertson tested something that's been known for years -- that the acuity of our color vision in the periphery of our visual field is fairly poor -- and challenged the prevailing explanation, which is that cones (our color-sensitive retinal cells) are dense in the fovea (center of the retina) and sparse in the edges.

[Image is in the Public Domain]

For one thing, "sparse" is comparative, and not even especially accurate.  In a normal retina, the periphery still has four thousand cones per square millimeter.  Plus, even the statement that peripheral color vision is bad turns out to be a misstatement; we can detect the color of a small, brightly-colored object almost as well in the periphery as we can in the dead center of the visual field.

However, Cohen, Botch, and Robertson did an experiment that turns the whole question upside down.  They gave test subjects head-mounted visual displays that were equipped with devices for tracking eye movements.  They then showed the test subjects images of outdoor scenes, and without alerting them, began to decrease the color saturation in the edges of the image.  The test subjects failed to notice the fact that the image was gradually turning to black-and-white from the edges inward until the colored bit spanned an angle of only 37.5 degrees, something that "does not correspond to known limitations imposed by retinal or neuroanatomy."

It appears that what's going on is that the edges of our visual field are reasonably good at recognizing color, but our brain simply ignores the input.  Motion, on the other hand, is quickly detected even in the peripheral vision; makes some sense evolutionarily, where seeing the lion coming up from behind you is way more critical than determining what color his fur is.

It was a fairly shocking result even for the researchers.  "We were amazed by how oblivious participants were when color was removed from up to 95 percent of their visual world," said study senior author Caroline Robertson, in an interview with EurekAlert.  "Our results show that our intuitive sense of a rich, colorful visual world is largely incorrect.  Our brain is likely filling in much of our perceptual experience."

How and why the brain does this, however, is still a mystery.  The authors write:

If color perception in the real world is indeed as sparse as our findings suggest, the final question to consider is how this can be.  Why does it intuitively feel like we see so much color when our data suggest we see so little?  While we cannot offer a definitive answer, several possibilities can be explored in future research.  One possibility is that as observers spend time in an environment, their brains are able to eventually “fill-in” the color of many items in the periphery.  Of course, providing direct evidence for this explanation is challenging since it is extremely difficult to differentiate between scenarios where a subject knows the color of an object (i.e., “I know the tree behind me is green even though I currently cannot see the color green”) from instances where the subject is experiencing the color of that object online (i.e., “I can see the color green at this very moment”).

So our umwelt is apparently an even smaller slice of reality than we'd thought.  A little humbling, and something to think about next time you're in an argument with someone and you are tempted to say, "I know it happened that way, I saw it with my own eyes."

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This week's Skeptophilia book-of-the-week is for people who are fascinated with the latest research on our universe, but are a little daunted by the technical aspects: Space at the Speed of Light: The History of 14 Billion Years for People Short on Time by Oxford University astrophysicist Becky Smethurst.

A whirlwind tour of the most recent discoveries from the depths of space -- and I do mean recent, because it was only released a couple of weeks ago -- Smethurst's book is a delightful voyage into the workings of some of the strangest objects we know of -- quasars, black holes, neutron stars, pulsars, blazars, gamma-ray bursters, and many others.  Presented in a way that's scientifically accurate but still accessible to the layperson, it will give you an understanding of what we know about the events of the last 13.8 billion years, and the ultimate fate of the universe in the next few billions.  If you have a fascination for what's up there in the night sky, this book is for you!

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Color my world

I'm guessing that every amateur philosopher has wondered if we all perceive color the same way -- for example, if what I perceive as "red" is the same as what you call "green," but we've just learned to both call it green.

I know I've been asked that probably dozens of times in my neuroscience classes, and my answer was always the same: it's possible, given that I can never see the world through your eyes and brain, but it's pretty unlikely because of the homology that exists between all human brains.  The fact that the visual/perceptive apparatus in your body is awfully similar to the one in mine suggests that we both perceive the world substantially the same way.

You can never prove it, though, which is why this question will keep coming up during late-night sessions in freshman dorms, lo unto the end of time.

Even though I'm making light of it, color perception is still quite a mystery.  It's known that most people (excluding the colorblind) have three different kinds of "cones," which are the cells in the retina that distinguish color, peaking in the red, blue, and green regions of the spectrum.  A few humans -- predominantly women, because the genes for the cone pigments are on the X chromosome -- are tetrachromats, and have a fourth type of cone, making their color acuity considerably more sensitive than the rest of us, and probably explaining the times my wife has said to me, "You actually think that shirt matches those pants?"

Then there's the mantis shrimp, a marine arthropod that is weird in a great many respects, not least because they have between twelve and sixteen different kinds of photoreceptors.  You have to wonder what the world looks like to them, don't you?

[Image is in the Public Domain]

This topic comes up because of a paper that appeared this week in the journal Cell, called "Color Categorization Independent of Color Naming," by a team led by Katarzyna Siuda-Krzywicka, a neuroscientist at Sorbonne University in Paris.  And what this research shows is that our ability to categorize colors -- to determine, for example, that vermilion and scarlet are both shades of red -- is independent of our ability to assign names to colors.

I know, pretty weird, isn't it?  The way that Siuda-Krzywicka and her team approached it was to give two different tasks to people, the first of which required you to identify by number which patches of color in a sample were shades of the same color (i.e., #1 and 2 are the same color, and they're different from #3), and the second of which was to identify what color a particular sample actually was (i.e., #1 is a shade of blue).  Neurotypical people can do both pretty well, with allowances for the aforementioned differences in color sensitivity between individuals.

Where it got interesting was that they included in their study a subject called "RDS" who had suffered an ischemic stroke involving his left posterior cerebral artery five years ago, damaging part of the left occipito-temporal region of his brain.  This stroke interfered with his ability to read and identify certain objects, but its effects were most pronounced in his ability to recognize colors.  When Siuda-Krzywicka's team tested RDS, a fascinating pattern emerged.

Task #1, where subjects were asked to do color categorization -- determine which patches were shades of the same color -- RDS did quite well on, and in fact was very close to the average for test subjects of his gender and age.  However, he was really awful at task #2, trying to figure out what color the patches actually were.

In other words, he could tell that ultramarine and azure were both shades of the same color, but he couldn't figure out that they were both shades of blue.

What this indicates is something very curious; our ability to name colors and our ability to recognize color categories are independent of each other.  You can impair one without affecting the other.

The most fascinating part is that the researchers noted that many of the times RDS did get the color name correct, it was because he used his relatively intact ability at categorization, plus his knowledge and memory, to arrive at an answer.  "This is the same color as blood," he said, "and I know blood is red, so this must be red as well."  Naming colors had to be done with a cognitive, logical process, not an automatic recognition as it is done by the rest of us.

It reminds me of my issue with recognizing faces, about which I've written here before.  Although I'm essentially face-blind, I can recognize people sometimes -- putting together what I remember of their hairstyle, coloration, whether or not they wear glasses, and even the way they stand or walk.  But it's nowhere near automatic; it's a logical sequence ("he's the guy who's tall and thin, wears wire-rim glasses, and has curly blond hair"), not an instantaneous recognition.  And it's easily foiled if a person changes hairstyles, wears more (or less) makeup than usual, or -- as I found out last year in one of my classes, when I at first didn't recognize a student I'd taught all year -- simply wears a baseball cap.

This research gives us a bit more information about the sometimes non-intuitive mechanisms by which we perceive the world.  The brain is a complex and fascinating machine.  As a former student once put it, "My brain is so complicated it can't even understand itself."  But it could be worse -- think of what it must be like to be a mantis shrimp.

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This week's Skeptophilia book recommendation is a classic: James Loewen's Lies My Teacher Told Me.  Loewen's work is an indictment not specifically of the educational system, but of our culture's determination to sanitize our own history and present our historical figures as if they were pristine pillars of virtue.

The reality is -- as reality always is -- more complex and more interesting.  The leaders of the past were human, and ran the gamut of praiseworthiness.  Some had their sordid sides.  Some were a strange mix of admirable and reprehensible.  But what is certain is that we're not doing our children, nor ourselves, any favors by rewriting history to make America and Americans look faultless.  We owe our citizens the duty of being honest, even about the parts of history that we'd rather not admit to.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Color commentary

The "what colors do you see in this photograph?" thing is back with us, only instead of a dress, this time it's a shoe.

Personally, I see this shoe as gray and a sort of turquoise-greenish-blue, but apparently there are people who see it as pink and white.  What's certain is that once you see it a particular way, you can't somehow see it the other way, as you can with flip-flop illusions like the famous duck and rabbit.

What's different about the claims floating around this time is that supposedly, the fact that I see it as gray and green means I'm a left-brain, logical, sequential, concrete type, and the people who see it as pink and white are right-brain creative, holistic, abstract thinkers.  The problem with this is that a 2017 study at the University of Utah concluded that there is nothing to the right-vs.-left brain dichotomy, at least insofar as personality is concerned.  "It is certainly the case that some people have more methodical, logical cognitive styles, and others more uninhibited, spontaneous style," said Jeffrey Anderson, a neuroscientist who co-authored the study.  "This has nothing to do on any level with the different functions of the [brain's] left and right hemisphere."

It is true that people do tend to have a dominant side of the brain, and this can influence you physically -- for example, what hand you write with and which eye is dominant.  I know on brain-dominance tests I tend to score right in the middle -- left on some tasks, right on others.  When I was in kindergarten I switched which hand I wrote with about a dozen times, till my frustrated teacher told me to simmer down and pick one, for pity's sake, so I ended up right handed.  But I still do a lot of things with my left hand, and probably would be considered mixed-brain dominant.

But the point here is, it has nothing whatsoever to do with my personality, nor with how I perceive color.

The unfortunate part is that this simplistic and inaccurate account of the gray/green vs. pink/white split ignores the fact that we do have a possible explanation for why this happens, and it's actually a good bit more interesting than "you're a right-brained creative type."  The reason seems to be that we evaluate and interpret colors by comparison with their context, not in any sense the "absolute color" of the object (which, as you'll see, is a meaningless concept).  As a rather startling illustration of this, how would you compare the color saturation of the two squares marked A and B in the drawing below?

Nearly everyone is absolutely convinced that A is a lot darker than B, but the fact is, they're exactly the same shade of gray.  The reason your brain made the decision that they're different -- a decision that, even once you know what's going on, is damn near impossible to shake -- is that you interpret B as if it were in a shadow, so in order to appear the shade it is, it must be inherently lighter.  If A and B were observed in the same level of light (your brain says), B would have to be lighter.

Even more striking is the image below:

I'm sure you've already figured out that the band in the middle is all the same shade of gray -- which you can prove to yourself by blocking out the background with a piece of paper.  But as I said, once your brain has made the decision that it's a gradient, it's impossible to compromise.

You do the same thing with colors.  Here's an example -- and once again, A, B, and C are all exactly the same color:

You get the point.  The thing is, you're doing this all the time without being aware of it, and once you have settled on what you're seeing, your brain won't admit it's wrong.  The same is happening with the shoes.  You decide which part of the image to compare the color to, and interpret every other color in the image on the basis of that decision.

We still don't know why some people settle on gray/green and others on pink/white.  But it has nothing to do with which side of the brain is dominant, nor whether you're creative or logical.  It has to do with our faulty method for integrating the data coming from our eyes.  It works well enough most of the time, sure; but when it fails, it fails spectacularly.

So feel free to repost the shoe pic and ask your friends which they see, but kindly don't attribute any differences to your favored side of the brain.  Instead, think about what's really going on here -- which, honestly, is far more interesting.

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I grew up going once a summer with my dad to southern New Mexico and southern Arizona, with the goal of... finding rocks.  It's an odd hobby for a kid to have, but I'd been fascinated by rocks and minerals since I was very young, and it was helped along by the fact that my dad did beautiful lapidary work.  So while he was poking around looking for turquoise and agates and gem-quality jade, I was using my little rock hammer to hack out chunks of sandstone and feldspar and quartzite and wondering how, why, and when they'd gotten there.

Turns out that part of the country has some seriously complicated geology, and I didn't really appreciate just how complicated until I read John McPhee's four-part series called Annals of the Former World.  Composed of Basin and Range, In Suspect Terrain, Rising from the Plains, and Assembling California, it describes a cross-country trip McPhee took on Interstate 80, accompanied along the way with various geologists, with whom he stops at every roadcut and outcrop along the way.  As usual with McPhee's books they concentrate on the personalities of the people he's with as much as the science.  But you'll come away with a good appreciation for Deep Time -- and how drastically our continent has changed during the past billion years.

[Note:  If you order this book using the image/link below, part of the proceeds will go to support Skeptophilia!]