Color my world

When you think about it, color perception is really strange.

Just about all of us have wondered whether we all see colors the same way -- if, for example, what you see as blue is the same as what I see as yellow, but we both identify them using the same word because there's no way to know we're not seeing them the same way.  I've always thought that unlikely.  After all, with few exceptions (other than genetic or structural abnormalities, about which q. v.) our eyes and brain are all built on the same basic plan.  I guess it's possible that we each see the world's colors differently, but the most parsimonious explanation is that because the underlying structures are the same, we're all pretty much perceiving identical color palettes.

Of course, there's no way to know for certain, and I ran into two things just in the last couple of days that leave me wondering.

The first is a curious conversation I had with my friend, the awesome writer Andrew Butters, whose books -- especially the staggeringly good Known Order Girls -- should be on everyone's TBR list.  It started out with an amusing discussion of words that sound like they should mean something else.  One of Andrew's was ambulatory, which to him sounds like "someone who is so incapacitated they need an ambulance."  I personally believe that pulchritude should mean "something that makes you want to puke," and not what it actually does, which is "beauty."  And then Andrew mentioned that he always thought the color words vermilion and chartreuse were wrong, and in fact backwards -- that vermilion should mean a light green and chartreuse a bright orangey-red.

This struck me as really weird, because those two words have never given me that sense.  This may be because I've known them both since I was little.  I knew vermilion because I grew up a mile away from Vermilion Bayou, so named because the red mud of southern Louisiana stains the water reddish brown.  Chartreuse I knew because my grandma's employer, Father John Kemps, was an eccentric, bookish, cigar-smoking Dutch expat who was very fond of a post-meal tipple and loved chartreuse, the pale green herbal French liqueur from which the color got its name.

So I asked Andrew where his misapprehension came from.  He said he wasn't sure, but that perhaps the vermilion one came from the French vert (green); Andrew, like most Canadians, is English-French bilingual.  But where his thinking chartreuse should mean "red" came from, he had no idea.

What baffled me further, though, was when he pointed out that he's not alone in this.  There's a whole page on Reddit about thinking that vermilion and chartreuse are backwards, and an astonishing number of people chimed in to say, "Yeah, me too!"  So why those particular words, and not another pair?  Why not citron and azure, or something?

The second is that I'm finally getting around to reading Oliver Sacks's book An Anthropologist on Mars, which has to do with the intersection between neurological disorders and creativity.  The very first chapter is about a painter who was in a car accident that resulted in brain damage causing cerebral achromotopsia -- complete colorblindness due not to abnormalities in the cones of the retina, but because of damage to a region of the brain called the V4 prestriate cortex.  Afterward, he saw the world in shades of gray -- but with some distinct oddities, because pure white surfaces looked "dirty" or "smudged" to him, red looked black, and blue looked a pale gray.

This brought up an interesting discussion about how we see color in the first place, and that color perception (even within a single, normally-sighted individual) isn't absolute, but comparative; we assess the color value of a region by comparison to the entire visual field.  If the whole "what color is this dress?" thing that was going around a few years ago didn't convince you of that, try this one out:

Every one of these spheres is exactly the same color; they were, in fact, cut-and-pasted from a single image.  The only thing that differs is the color of the foreground stripes that cross each one.  But since your eyes judge color based on context, it's impossible to see them as the same even once you cognitively know what's going on.

Don't believe it?  If you go to the link provided, the article author (the wonderful Phil Plait) created an animation that cycles between the image with and without the stripes.  It's mind-blowing.

All of this circles around to the weird topic of synesthesia, which is a still-unexplained sensory phenomenon where people have a sort of cross-wiring between two senses.  Russian composer Alexander Scriabin was a synesthete, who experienced sensations of colors when he heard chords; C# minor, for example, looked a bright emerald green.  (If you want to find out more, the amazing book by Richard Cytowic, The Man Who Tasted Shapes, is still considered one of the seminal works on this odd disorder.)

I wonder if what Andrew (and the others with the vermilion-chartreuse switch) are experiencing is a form of synesthesia.  A former student of mine is a synesthete for whom printed letters (and whole words) evoke sensations of colors, so his word choices while writing took into account whether the colors were harmonious, not just that the words made semantic sense.  (I hasten to add that he was and is one of the most brilliant people I've ever known, so his synesthesia didn't cause his writing to lack any clarity to non-synesthetes like myself -- although it has been known to slow him down as he struggled to find words that satisfied both meaning and appearance.)  So perhaps the "vermilion = light green" thing comes from the fact that for Andrew and the others on the Reddit page, the word looks green irrespective of its association with an actual (different) color.

What I find odd still, though, is that so many people have those two particular color words backwards.  Synesthesia is remarkably individual; while one of its hallmarks is a complete consistency within a particular person (Scriabin always saw C# minor as green, for example), it varies greatly from person to person.  The fact that vermilion and chartreuse are reversed for so many people is just plain peculiar.

So there's still a lot we don't know about how exactly we perceive color, and maybe my "parsimonious" explanation that (other than those with colorblindness, synesthesia, and other visual disorders) we're all seeing colors more or less the same way fails to capture the complexity of the real world.  Wouldn't be the first time I've thought things were simpler than they turned out to be.  Maybe it's just my perception because I'm a non-synesthete with intact color vision.

But until we're somehow able to see things through someone else's eyes and brain, that's a limitation I can't escape except for in my imagination.

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Cats in boxes

Any cat owners amongst my readers will undoubtedly know about the strange propensity of cats to climb into boxes.  Apparently it works for cats of all sizes:

With apologies to Robert Burns, a cat's a cat for a' that.

In fact, it doesn't even have to be a real box:

I've never heard a particularly convincing explanation of why cats do this.  Some people suggest it's because being in close quarters gives them a sense of security, perhaps a remnant of when they lived in the wild and slept in burrows or caves.  Me, I suspect it's just because cats are a little weird.  I've been of this opinion ever since owning a very strange cat named Puck, who used to sleep on the arm of the couch with one front and one back leg hanging limp on one side of the arm and the other two dangling over the other side, a pose that earned her the nickname "Monorail Cat."  She also had eyes that didn't quite line up, and a broken fang that caused her tongue to stick out of one side of her mouth.  She was quite a sweet-natured cat, really, but even people who love cats thought Puck looked like she had a screw loose.

The topic comes up because of a delightful piece of research in the journal Applied Animal Behaviour Science.  The paper was titled "If I Fits, I Sits: A Citizen Science Investigation into Illusory Contour Susceptibility in Domestic Cats," by Gabriella Smith and Sarah-Elizabeth Byosiere (of Hunter College) and Philippe Chouinard (of LaTrobe University), and looked at data collected from cat owners to find out if cats are fooled by the Kanizsa Rectangle Illusion.

The Kanizsa Rectangle Illusion is an image that tricks the brains into seeing contours that aren't there.  Here's one representation of it:

To most people, this looks like an opaque white rectangle laid over four black hexagons, and not what it really is -- four black hexagons with triangular wedges cut out.  Apparently the brain goes with an Ockham's Razor-ish approach to interpreting what it sees, deducing that a white rectangle on top of black hexagons is much more likely than having the cut-out bits just happening to line up perfectly.  It's amazing, though, how quickly this decision is made; we don't go through a back-and-forth "is it this, or is it that?"; the illusion is instantaneous, and so convincing that many of us can almost see the entire boundary of the rectangle even though there's nothing there.

Well, apparently, so can cats.  And, as one would expect, they sit in the middle of the nonexistent rectangle just as if it was a real box.  The authors write:

A well-known phenomenon to cat owners is the tendency of their cats to sit in enclosed spaces such as boxes, laundry baskets, and even shape outlines taped on the floor.  This investigative study asks whether domestic cats (Felis silvestris catus) are also susceptible to sitting in enclosures that are illusory in nature, utilizing cats’ attraction to box-like spaces to assess their perception of the Kanizsa square visual illusion...  [T]his study randomly assigned citizen science participants booklets of six randomized, counterbalanced daily stimuli to print out, prepare, and place on the floor in pairs.  Owners observed and videorecorded their cats’ behavior with the stimuli and reported findings from home over the course of the six daily trials...  This study revealed that cats selected the Kanizsa illusion just as often as the square and more often than the control, indicating that domestic cats may treat the subjective Kanizsa contours as they do real contours.

It's a fascinating result, and indicative that other animal species see the world much as we do.  It still doesn't explain why cats like to sit in boxes, though.  I think my conclusion ("cats are weird") covers it about as well as anything.  But at least in one way, our perceptual/interpretive centers are just as weird as the cats' are.  I'm not inclined to go sit in a box, but it does make me wonder what our pets would think if we showed them other optical illusions.

I doubt my dogs would be interested.  If what they're looking at has nothing to do with food, petting, napping, or playing, they pretty much ignore it.  Must be nice to see the world in such simple terms.

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Off kilter

I got an interesting email a few days ago, which I quote (with permission):

I keep running into references to places called "gravity hills" or "magnetic hills" where supposedly some force plays hell with your sense of what's up and what's down.  Trees and walls appear to lean, it's hard to stand up right, stuff like that.  But people say it's more than an illusion, because cars put in neutral at the bottom of an incline roll uphill, and balls placed on what appear to be level surfaces start to roll.

I can't come up with any way any of this could be real, but there are a lot of claims, so it's kind of the "can they all be false?" thing.  What do you know about this, and has it been explained scientifically?  Or is there really something paranormal going on?

I've heard about this phenomenon for years myself, and saying "there are a lot of claims" is a bit of an understatement.  In fact, Wikipedia has a list of reports of such "mystery hills" everywhere from Azerbaijan to Uruguay, and they all kind of have the same characteristics -- that the laws of gravity don't seem to apply, or that there's a strange "magnetic force" pulling stuff (including your proprioception) off kilter.

Let's clear one thing up from the get-go, though; if there is anything going on here, it has nothing to do with magnetism, because our sense of balance is controlled by the semicircular canals, fluid-filled tubes in your inner ear that use the movement of the liquid under the pull of gravity as a way of communicating to your brain "that direction is down."  Messing with this will make you dizzy and/or nauseated, which is why people get motion sickness; the apparent forces caused by spinning around on a carnival ride cause the fluid to slosh about, sending mixed signals to the brain and making some people violently ill.  (Why certain people seem to be more or less immune to motion sickness, and others get nauseated walking across the room, is unknown.)

So even if there was some mysterious "magnetism" at work here, it wouldn't affect your sense of balance unless your inner ears were made of cast iron.

But let's get down to specifics.  Here's how one of the most famous "mystery hills," the "Oregon Vortex," is described in John Godwin's book This Baffling World:

Situated thirty miles from Grant's Pass, the vortex -- which measures roughly 125 feet in diameter -- constitutes, according to its promoters, an electromagnetic phenomenon.

Within the "Oregon Vortex" there stands a hut, dubbed "The House of Mystery."  Its owner, John Lister, says, "Nowever in the area does the visitor stand upright.  Inevitably one assumes a posture that inclines toward magnetic north, beginning with a minimum of divergence from normal at the edge of the area, and increasing to an acute angle as "The House of Mystery" is entered.  So gradually is this latter stage reached that visitors seldom realize the phenomenon until the seemingly impossible posture of the guide or their friends brings a realization of their own tilting."

Suspended from the roof of "The House of Mystery" hangs a heavy steel ball, but that ball presumably doesn't hang straight down.  It would seem to lean inward, pulled toward the center of the hut by some weird gravitational shift.  It is claimed that a person who enters the hut will feel the odd pull quite distinctly; it is further alleged that the power which is exerted will force one to lean over at a ten-degree angle.  Viewers have alleged that a rubber ball, placed on the floor here, will roll uphill.

Another famous one is Magnetic Hill, near Moncton, New Brunswick, where a landmark (a light-colored telephone pole) appears to be the lowest point in the road when viewed from one direction, and the highest when viewed from the other.

[Image licensed under the Creative Commons Jim101, Magnetic Hill Moncton Front, CC BY-SA 3.0]

And of course, these stories are always accompanied with claims of other sorts of paranormal occurrences -- UFOs, ghosts, "skinwalkers," and the like -- and, in the United States at least, the inevitable stories about how the Indigenous people thought the place was cursed or haunted or a sacred burial ground or whatnot.

Now, to address the question -- is there anything to this?

Simple answer: no.

It turns out that humans are remarkably bad at piecing together visual cues with the information we get from our semicircular canals and coming up with a coherent picture of what the space around us is doing.  All it takes is a little messing about with the information we're receiving, and it befuddles us completely.

Take, for example, the following rather simple drawing:

[Image licensed under the Creative Commons Fibonacci, Zöllner illusion, CC BY-SA 3.0]

The diagonal lines running from the upper left to the lower right are all parallel, despite the fact that (1) they don't look it, and (2) even when you know what's going on and have proven it to yourself with a ruler, they still don't look it.  This is called the Zöllner Illusion, named after its discoverer, the astrophysicist Johann Karl Friederich Zöllner, and is a good indication that our ability to orient visually is not all it's cracked up to be.  (This is why the first thing pilots-in-training are taught is, "trust your instruments, not your senses.")

The "gravity hill" phenomenon is actually nothing more than an optical illusion as well, created by tilted surfaces that appear to be flat (or vice-versa) because the horizon is obscured, landmarks themselves are at an angle, or something is causing the eyes to misperceive the angle of inclination.  The whole thing was the subject of an extensive investigation that resulted in a paper in the journal Psychological Science, which concluded that the phenomenon is the result of a place's odd spatial layout combined with our faulty sensory-perceptive equipment.

So there's no alteration in the pull of gravity in these spots, or a mysterious electromagnetic anomaly, or a Great Disturbance in the Force, or whatever.  I'm not saying they're not fun; optical illusions are endlessly fascinating to me, but it's from the perspective of "wow, our brains are super easy to fool," not because of anything paranormal going on.

Anyhow, thanks to the reader who sent the question.  I always appreciate inquiries.  My opinion is that all of science starts from a desire to go from "We don't know" to "That's curious" to "Let's find out how it works."  

And even if in this case, the answer turns out to be less exciting than a rip in the space-time continuum, it's still pretty interesting.

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Trompe l'oeil

I have a fascination for optical illusions.

Not only are they cool, they often point out some profound information about how we process sensory input.  Take the famous two-and-a-half pronged fork:

The problem here is that we're trying to interpret a two-dimensional drawing as if it were a three-dimensional object, and the two parts of the drawing aren't compatible under that interpretation.  Worse, when you try to force your brain to make sense of it -- following the drawing from the bottom left to the top right, and trying to figure out when the object goes from three prongs to two -- you fail utterly.

Neil deGrasse Tyson used optical illusions as an example of why we should be slow to accept eyewitness testimony.  "We all love optical illusions," he said. "But that's not what they should call them.  They should call them 'brain failures.'  Because that's what they are.  A clever drawing, and your brain can't handle it."

(If you have some time, check out this cool compendium of optical illusions collected by Michael Bach, which is even more awesome because he took the time to explain why each one happens, at least where an explanation is known.)

It's even more disorienting when an illusion occurs because of two senses conflicting.  Which was the subject of a paper out of Caltech, "What You Saw Is What You Will Hear: Two New Illusions With Audiovisual Postdictive Effects," by Noelle R. B. Stiles, Monica Li, Carmel A. Levitan, Yukiyasu Kamitani, and Shinsuke Shimojo.  What they did is an elegant experiment to show two things -- how sound can interfere with visual processing, and how a stimulus can influence our perception of an event, even if the stimulus occurs after the event did!

Sounds like the future affecting the past, doesn't it?  It turns out the answer is both simpler and more humbling; it's another example of a brain failure.

Here's how they did the experiment.

In the first trial, they played a beep three times, 58 milliseconds apart.  The first and third beeps were accompanied by a flash of light.  Most people thought there were three flashes -- a middle one coincident with the second beep.

The second setup was, in a way, opposite to the first.  They showed three flashes of light, on the right, middle, and left of the computer screen.  Only the first and third were accompanied by a beep.  Almost everyone didn't see -- or, more accurately, didn't register -- the middle flash, and thought there were only two lights.

Sorry, I had to.

"The significance of this study is twofold," said study co-author Shinsuke Shimojo.  "First, it generalizes postdiction as a key process in perceptual processing for both a single sense and multiple senses.  Postdiction may sound mysterious, but it is not—one must consider how long it takes the brain to process earlier visual stimuli, during which time subsequent stimuli from a different sense can affect or modulate the first.  The second significance is that these illusions are among the very rare cases where sound affects vision, not vice versa, indicating dynamic aspects of neural processing that occur across space and time.  These new illusions will enable researchers to identify optimal parameters for multisensory integration, which is necessary for both the design of ideal sensory aids and optimal training for low-vision individuals."

All cool stuff, and more information about how the mysterious organ in our skull works.  Of course, this makes me wonder what we imagine we see because our brain anticipates that it will there, or perhaps miss because it anticipates that something out of of place shouldn't be there.  To end with another quote from Tyson: "Our brains are unreliable as signal-processing devices.  We're confident about what we see, hear, and remember, when in fact we should not be."

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It's a bird, it's a plane... no, it's both

One topic I've come back to over and over again here at Skeptophilia is how flawed our sensory/perceptive apparatus is.  Oh, it works well enough; most of the time, we perceive the external world with sufficient clarity not to walk into walls or get run over by oncoming trains.  But our impression that we experience the world as it is -- that our overall ambient sense of everything around us, what the brilliant neurophysiologist David Eagleman calls our umwelt, is a crystal-clear reflection of the real universe -- simply is false.

All it takes is messing about with optical illusions to convince yourself how easy our brains and sensory organs are to fool.  For example, in the following drawing, which is darker; square A or square B?

They're exactly the same.  Don't believe me?  Here's the same drawing, with a pair of gray lines superimposed on it:

Because your brain decided that B was in the shadow and A wasn't, then it concluded that A had to be intrinsically darker.  What baffles me still about this illusion is that even once you know how the trick works, it's impossible to see it any other way.

As astronomer Neil deGrasse Tyson put it, "Our brains are rife with ways of getting it wrong.  You know optical illusions?  That's not what they should call them.  They should call them brain failures.  Because that's what they are.  A few cleverly drawn lines, and your brain can't handle it."

Well, we just got another neat hole shot in our confidence that what we're experiencing is irrefutable concrete reality with a study that appeared in the journal Psychological Science this week.  What the researchers did was attempt to confound the senses of sight and hearing by showing test subjects a photograph of one object morphing into another -- say, a bird into an airplane.  During the time they studied the photograph, they were exposed to a selection from a list of sounds, two of which were relevant (birdsong and the noise of a jet engine) and a number of which were irrelevant distractors (like a hammer striking a nail).

They were then told to use a sliding scale to estimate where in the transformation of bird-into-airplane the image was (e.g. seventy percent bird, thirty percent airplane).  What the researchers found was that people were strongly biased by what they were hearing; birdsong biased the test subjects to overestimate the birdiness of the photograph, and reverse happened with the sound of a jet engine.  The irrelevant noises didn't effect choice (and thus, when exposed to the irrelevant noises, their visual perceptions of the image were more accurate).

"When sounds are related to pertinent visual features, those visual features are prioritized and processed more quickly compared to when sounds are unrelated to the visual features," said Jamal Williams, of the University of California - San Diego, who led the study, in an interview with Science Daily.  "So, if you heard the sound of a birdsong, anything bird-like is given prioritized access to visual perception.  We found that this prioritization is not purely facilitatory and that your perception of the visual object is actually more bird-like than if you had heard the sound of an airplane flying overhead."

I guess it could be worse; at least hearing birdsong didn't make you see a bird that wasn't there.  But it does once again make me wonder how eyewitness testimony is still considered to carry the most weight in a court of law when experiment after experiment has demonstrated not only how incomplete and easily biased our perceptions are, but how flawed our memories are.

Something to keep in mind next time you are tempted to say "I know it happened that way, I saw it with my own eyes."

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The mental starburst

Eminent astrophysicist Neil de Grasse Tyson was talking about the unreliability of the human sensory-perceptive system -- how, despite our confidence in what we see and hear, so often it is inaccurate or incomplete -- and said, "You know those trick drawings... optical illusions?  Well, that's not what they should call them.  They should call them 'brain failures.'  Because that's what they are.  A few cleverly drawn lines on a sheet of paper, and your brain can't handle it."

I've been interested in optical illusions -- or brain failures, if you prefer -- for a long time.  I think the feature of this phenomenon that intrigues me the most is the fact that even once you know what's going on, you still can't see it for what it is.  Here's one of the best examples of that I've ever seen:

Japanese artist Kokichi Sugihara created this, and others like it, that defy our expectation of how the world works.  Note that when the whole apparatus is rotated, and you see how it's done, it doesn't help.  You'd think your knowledge that gravity does indeed pull things toward the Earth, plus your knowledge of how exactly your eye was tricked, would be enough for the brain to go, "Oh, okay!  I get it now!  Duh!"

But no.  He rotates the apparatus back to its original configuration, and presto!  Upside-down gravity again.

The reason the topic comes up is because of a paper in the journal Perception this week about a fascinating illusion called the "scintillating starburst."  Here's what it looks like:

What do you see here?  If you're like me (and apparently most people), besides the obvious dark interlocking polygons, you see a pattern of light-colored lines radiating out from the center.

You've undoubtedly already guessed what the problem is; those lines don't exist.  Your brain, in effect, created those lines.  But how?  And why?

The authors write:

[The scintillating starburst illusion is] a unique kind of stimulus that evokes ghostly or ephemeral illusory rays that appear to shimmer or scintillate... We ascertained that the [effect] experienced by observers when viewing this stimulus type is modulated by all stimulus dimensions we suspected to be relevant when piloting the study, namely the number of vertices of the polygons, contrast, the line width of the wreaths, the number of wreaths, and whether the polygons are bisecting or not. The strongest effect was yielded by the number of wreaths, followed by whether the strands are bisecting, stimulus contrast, line width of the braids, and the number of vertices of the polygons, in that order...  [N]o stimulus dimension by itself produces a strong effect, only the optimal confluence of many stimulus parameters does so.  We believe that these results are consistent with probabilistic inference—for instance, the percept of illusory lines from an occluder is more likely if there are more intersection points where the vertices bisect, and if this happens at higher contrast.  This is not implausible, as deciding on a coherent interpretation of ambiguous visual information is a fundamental challenge faced by the visual system.  Of course, probability by itself is not sufficient—the specific stimulus situation matters—for instance, a row of street lights does not evoke the impression of a bright band that connects them.  But in the case of street lights, the bright beacons are broken up by the darkness of the night.  This darkness is unambiguously present.  However, in the case of Starbursts, the bright beacons are separated by background of the same color, yielding the percept of an occluder of that color on top of the stimulus.

What I find puzzling about this explanation is the last bit -- that we don't see a bright band connecting streetlights at night, because there is the unambiguous presence of darkness between the lights -- doesn't really account for seeing bright lines where none exist.  After all, the entire background is the same color; our brains generate an illusion that the vertices of the polygons are connected by radial lines even though the entire area is unambiguously the same shade of gray.

What I'd like to see is how the brain is actually responding -- perhaps fMRIs of people looking at the polygons with no braiding and concentric patterns, then a pattern of actual radial lines, then the illusion itself.  My guess is that the last two would activate the same parts of the brain and the first would not.  It might not explain why it happens, but at least we'd see what module is being tricked.

So here we have once again an example of how our brains, when confronted with quite ordinary stimuli, proceed to make shit up.  

Think about that next time you're tempted to say, "Of course it happened that way.  I saw it with my own eyes."

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One of the most devastating psychological diagnoses is schizophrenia.  United by the common characteristic of "loss of touch with reality," this phrase belies how horrible the various kinds of schizophrenia are, both for the sufferers and their families.  Immersed in a pseudo-reality where the voices, hallucinations, and perceptions created by their minds seem as vivid as the actual reality around them, schizophrenics live in a terrifying world where they literally can't tell their own imaginings from what they're really seeing and hearing.

The origins of schizophrenia are still poorly understood, and largely because of a lack of knowledge of its causes, treatment and prognosis are iffy at best.  But much of what we know about this horrible disorder comes from families where it seems to be common -- where, apparently, there is a genetic predisposition for the psychosis that is schizophrenia's most frightening characteristic.

One of the first studies of this kind was of the Galvin family of Colorado, who had ten children born between 1945 and 1965 of whom six eventually were diagnosed as schizophrenic.  This tragic situation is the subject of the riveting book Hidden Valley Road: Inside the Mind of an American Family, by Robert Kolker.  Kolker looks at the study done by the National Institute of Health of the Galvin family, which provided the first insight into the genetic basis of schizophrenia, but along the way gives us a touching and compassionate view of a family devastated by this mysterious disease.  It's brilliant reading, and leaves you with a greater understanding of the impact of psychiatric illness -- and hope for a future where this diagnosis has better options for treatment.

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

 

Cats in boxes

Any cat owners amongst my readers will undoubtedly know about the strange propensity of cats to climb into boxes.  Apparently it works for cats of all sizes:

With apologies to Robert Burns, a cat's a cat for a' that.

In fact, it doesn't even have to be a real box:

I've never heard a particularly convincing explanation of why cats do this.  Some people suggest it's because being in close quarters gives them a sense of security, perhaps a remnant of when they lived in the wild and slept in burrows or caves.  Me, I suspect it's just because cats are a little weird.  I've been of this opinion ever since owning a very strange cat named Puck, who used to sleep on the arm of the couch with one front and one back leg hanging limp on one side of the arm and the other two dangling over the other side, a pose that earned her the nickname "Monorail Cat."  She also had eyes that didn't quite line up, and a broken fang that caused her tongue to stick out of one side of her mouth.  She was quite a sweet-natured cat, really, but even people who love cats thought Puck looked like she had a screw loose.

The topic comes up because of a delightful piece of research that came out a few days ago in the journal Applied Animal Behaviour Science.  The paper was titled "If I Fits, I Sits: A Citizen Science Investigation into Illusory Contour Susceptibility in Domestic Cats," by Gabriella Smith and Sarah-Elizabeth Byosiere (of Hunter College) and Philippe Chouinard (of LaTrobe University), and looked at data collected from cat owners to find out if cats are fooled by the Kanizsa Rectangle Illusion.

The Kanizsa Rectangle Illusion is an image that tricks the brains into seeing contours that aren't there.  Here's one representation of it:

To most people, this looks like an opaque white rectangle laid over four black hexagons, and not what it really is -- four black hexagons with triangular wedges cut out.  Apparently the brain goes with an Ockham's Razor-ish approach to interpreting what it sees, deducing that a white rectangle on top of black hexagons is much more likely than having the cut-out bits just happening to line up perfectly.  It's amazing, though, how quickly this decision is made; we don't go through a back-and-forth "is it this, or is it that?"; the illusion is instantaneous, and so convincing that many of us can almost see the entire boundary of the rectangle even though there's nothing there.

Well, apparently, so can cats.  And, as one would expect, they sit in the middle of the nonexistent rectangle just as if it was a real box.  The authors write:

A well-known phenomenon to cat owners is the tendency of their cats to sit in enclosed spaces such as boxes, laundry baskets, and even shape outlines taped on the floor.  This investigative study asks whether domestic cats (Felis silvestris catus) are also susceptible to sitting in enclosures that are illusory in nature, utilizing cats’ attraction to box-like spaces to assess their perception of the Kanizsa square visual illusion...  [T]his study randomly assigned citizen science participants booklets of six randomized, counterbalanced daily stimuli to print out, prepare, and place on the floor in pairs.  Owners observed and videorecorded their cats’ behavior with the stimuli and reported findings from home over the course of the six daily trials...  This study revealed that cats selected the Kanizsa illusion just as often as the square and more often than the control, indicating that domestic cats may treat the subjective Kanizsa contours as they do real contours.

 It's a fascinating result, and indicative that other animal species see the world much as we do.  It still doesn't explain why cats like to sit in boxes, though.  I think my conclusion ("cats are weird") covers it about as well as anything.  But at least in one way, our perceptual/interpretive centers are just as weird as the cats' are.  I'm not inclined to go sit in a box, but it does make me wonder what our pets would think if we showed them other optical illusions.

I doubt my dogs would be interested.  If what they're looking at has nothing to do with food, petting, or playing, they pretty much ignore it.  Must be nice to see the world in such simple terms.

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Ever get frustrated by scientists making statements like "It's not possible to emulate a human mind inside a computer" or "faster-than-light travel is fundamentally impossible" or "time travel into the past will never be achieved?"

Take a look at physicist Chiara Marletto's The Science of Can and Can't: A Physicist's Journey Through the Land of Counterfactuals.  In this ambitious, far-reaching new book, Marletto looks at the phrase "this isn't possible" as a challenge -- and perhaps, a way of opening up new realms of scientific endeavor.

Each chapter looks at a different open problem in physics, and considers what we currently know about it -- and, more importantly, what we don't know.  With each one, she looks into the future, speculating about how each might be resolved, and what those resolutions would imply for human knowledge.

It's a challenging, fascinating, often mind-boggling book, well worth a read for anyone interested in the edges of scientific knowledge.  Find out why eminent physicist Lee Smolin calls it "Hugely ambitious... essential reading for anyone concerned with the future of physics."

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

 

Halos and shadows

About two weeks ago, I wrote a piece here about a Scottish cryptid called the Am Fear Liath Mòr -- which roughly translates from Gaelic as "the big gray dude" -- a horrifying apparition that has been seen in the Cairngorms of northern Scotland.  It's described as a human figure, but huge and hulking, that appears in the distance, understandably creating "uneasy feelings" in the observer.

As I mentioned in my previous post, if I were to see such a thing, my "uneasy feelings" would include being so terrified I'd drop dead of a brain aneurysm.  Because I'm just that brave.

Well, thanks to a friend and long-time loyal reader of Skeptophilia, I've learned that this might be an unfortunate overreaction on my part.  The Am Fear Liath Mòr may have a completely rational, scientific explanation, and one that doesn't require belief in some enormous Sasquatch knock-off wandering around in the Highlands.  It seems like the Scottish Big Gray Dude might be an example of a phenomenon that occurs in foggy mountains called the "Brocken spectre."

The Brocken spectre (or "Brocken bow") is an optical effect that occurs when there are eye-level uniformly-dispersed water droplets of all about the same size -- as you find in a fog bank -- and you're backlit by sunlight.  This requires specific conditions, not only fog in front of you, but it being clear enough behind you that there's sufficient sunlight to cast a shadow.  The result is that your shadow, or more accurately the light rays that outline it, are refracted and reflected by the water droplets in the fog, creating a hugely magnified shadow surrounded by a halo of glare, sometimes with a rainbow sheen.

A Brocken spectre photographed near the Golden Gate Bridge, San Francisco, California [Image licensed under the Creative Commons Brocken Inaglory, Solar glory and Spectre of the Brocken from GGB on 07-05-2011, CC BY-SA 3.0]

The phenomenon gets its name from the Brocken, a peak in the Harz Mountains of Germany, where it has been observed for centuries, and was described in detail by scientist Johann Silberschlag in 1780.  The idea of the allegedly-supernatural Brocken spectre being nothing more than an optical illusion generated by a shadow and the refractive effects of water droplets is supported by the fact that it's always seen in the fog when the Sun is behind you, and it seems to shift size unpredictably -- unsurprising if you're moving (which I sure as hell would be if I saw one), and there's a breeze making the fog bank waver and shift.

So it turns out that the Big Gray Dude of Scotland may not be a cryptid at all, just a weird -- and fascinating -- localized weather phenomenon.  And it also accounts for other instances of eerie figures in the mist, such as the "Dark Watchers" of the Santa Lucia Mountains in California and the strange looming presence reported by British mountaineer Eric Shipton while climbing Mount Kenya.  It's also related to the optical phenomenon called heiligenschein ("holy light") which probably accounts for instances of people being seen surrounded by what appears to be a ghostly halo.  The somewhat anticlimactic explanation for this latter effect is that it's not Tongues of Fire or the Radiance of God descending upon you, it's light scattering and a thoroughly understood mechanism called retroreflection that happens regardless of the holiness level of the person involved.

In any case, one more win for the scientific approach, even if it kind of blows away the mystique of a giant scary shadow-man wandering about in the Scottish Highlands.  Skeptic though I am, I have to admit to being a little disappointed.  It seems like if there's anywhere that should actually be haunted, it's the Cairngorms.  But even so, it's somehow fitting that the thing that has been terrifying the superstitious for centuries turns out to be nothing more than...

... their own shadows.

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Last week's Skeptophilia book-of-the-week, Simon Singh's The Code Book, prompted a reader to respond, "Yes, but have you read his book on Fermat's Last Theorem?"

In this book, Singh turns his considerable writing skill toward the fascinating story of Pierre de Fermat, the seventeenth-century French mathematician who -- amongst many other contributions -- touched off over three hundred years of controversy by writing that there were no integer solutions for the equation  aⁿ + bⁿ = cⁿ for any integer value of n greater than 2, then adding, "I have discovered a truly marvelous proof of this, which this margin is too narrow to contain," and proceeding to die before elaborating on what this "marvelous proof" might be.

The attempts to recreate Fermat's proof -- or at least find an equivalent one -- began with Fermat's contemporaries, Evariste de Gaulois, Marin Mersenne, Blaise Pascal, and John Wallis, and continued for the next three centuries to stump the greatest minds in mathematics.  It was finally proven that Fermat's conjecture was correct by Andrew Wiles in 1994.

Singh's book Fermat's Last Theorem: The Story of a Riddle that Confounded the World's Greatest Minds for 350 Years describes the hunt for a solution and the tapestry of personalities that took on the search -- ending with a tour-de-force paper by soft-spoken British mathematician Andrew Wiles.  It's a fascinating journey, as enjoyable for a curious layperson as it is for the mathematically inclined -- and in Singh's hands, makes for a story you will thoroughly enjoy.

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

Canine illusions

I've always had a fascination for optical illusions.

The enjoyment of bizarre trompe-l'oeil is connected to a persistent theme in my fiction; how do we know what's real?  If something occurs that challenges our notions of how things are, by what criteria could we know if we're seeing reality -- or if it's a malfunction in our frequently errant sensory-perceptual systems?

My favorite optical illusions are ones where even once you know what's going on, your mind just won't accept it.  Our brains, apparently, are very prone to hanging on to a solution to a perceptual anomaly even once it's been conclusively demonstrated that they've got it wrong.  The best example of this I know of is the checker shadow illusion:

In the above image, which square is darker, A or B?

If you know anything about optical illusions, you've probably guessed that they're the same darkness, and you'd be right if you did.  But I'd bet cold hard cash that even once you know the two squares are the same darkness, you can't actually see it that way.  (In fact, if you doubt they are of equal darkness, use some scraps of paper to cover up everything but a vertical strip of the image, to eliminate the green cylinder and most of the checkerboard.  The fact that they're the same will be obvious.  Then remove the paper, and voilà -- you'll be back to seeing A as darker than B.)

Another fine example of this phenomenon is the hollow-face illusion, which seems to occur because our brains have a finely-developed ability to see nuances of other human faces, but the concept of an inside-out face is so far out of anything we typically experience that we just can't process it.  Check it out:

A lot of optical illusions have to do with the fact that we often interpret what we see based upon comparisons, and those comparisons persist even once we know they're inaccurate.  (That's the key to the checker shadow illusion; because we think square B is in shadow, it must be intrinsically lighter in color than square A.)  It's also what made the infamous blue dress/white dress illusion so maddening; apparently it works because we judge something's color not only by the intrinsic frequencies of the light striking our eye, but by comparison to the color(s) surrounding it.  So someone who focuses on one part of an image and judges the rest of the image based upon that will come to a different conclusion than someone who does the same thing but starting with a different part of the image.

A lot of size-based illusions work in a similar fashion, such as the Ebbinghaus-Titchener illusion, in which the question is to determine which of the two orange circles is larger:

You've undoubtedly already guessed that they're the same size, but it's a remarkably persistent illusion even when you know that.  The right-hand circle looks larger because we're judging its size by comparison to the small dots surrounding it; and the opposite holds for the left-hand circle.

The topic of optical illusions comes up because of a cool study out of La Trobe University (Australia), led by psychologist Sarah Byosiere.  Byosiere became interested in optical illusions a few years ago, and wondered whether humans' advanced brains made us fall for them more easily -- we're always calculating, comparing, weighing options, which brings with it some pitfalls -- and whether other animal species might not be fooled.

So she decided to test dogs.  Using copious amounts of dog cookies, she trained some dogs to interact with a touch screen, rewarding the dogs if they touched their noses to the larger of two circular shapes shown.  Once they got good at it, she threw the Ebbinghaus-Titchener illusion at them.

And they fell for it.  Apparently dogs think the right-hand circle is larger, too.

What's even more fascinating is that dogs didn't fall for the Delboeuf illusion...

 ...which you'd think would work precisely the same way.  Getting tricked by the Delboeuf illusion is apparently pretty ubiquitous in humans, which is why restaurants have discovered that a medium-sized entrée looks like a more generous serving in a small plate than in a larger one.  But dogs presented with two plates of food, which differ in the plate size but not in the quantity of food, showed no preference whatsoever for the smaller plate.

As a side note, however, I do wonder if the apparent failure of dogs to get taken in by the Delboeuf illusion isn't because of faulty experimental design.  I know my own dogs don't seem to respond to portion size in their (equal-sized) food bowls.  I can fill one to overflowing and put only a handful of kibble in the other, and my dogs will generally go for whichever bowl is closer.  "Oh, well, I can always go for the other bowl once I'm done with this one," seems to be their general attitude, along with "Any food is a good thing."

Byosiere and her colleagues have expanded their research into other illusions, and I encourage you to go to the link I posted and check out what she and others have done.  She's also started a citizen-science effort called “What the Fluff!?” to study how animals respond to an illusion you probably have seen on YouTube -- where a pet owner holds a sheet up in front of them, and drops the sheet while simultaneously ducking out of sight, and seeing how the pets respond to their owners' apparent vanishing act.  "We’re asking owners to do this at home with their dogs," Byosiere said.  "We’ll be analyzing the footage and seeing if we can make any conclusions about object permanence and violation of expectation in that kind of magic trick."

So if you're inclined, try playing some mind games with your pets, and send her your results.  I may try it with my dogs and see what happens.  My guess is Guinness might fall for it and try to figure out what happened, but our hound Lena, who shows the level of energy and intelligence usually associated with a plush toy, would probably not notice if I mysteriously vanished.  Or if she did notice, she'd kind of shrug and go, "Oh, well, I'm sure he'll be back at some point" and resume the very important nap she'd been taking before I started bothering her.

Either way, it might be interesting to see how they respond.  If you try it, let me know in the comments section what your results were.  And now, I'm off to play a round of Confuse-a-Dog.

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What are you afraid of?

It's a question that resonates with a lot of us.  I suffer from chronic anxiety, so what I am afraid of gets magnified a hundredfold in my errant brain -- such as my paralyzing fear of dentists, an unfortunate remnant of a brutal dentist in my childhood, the memories of whom can still make me feel physically ill if I dwell on them.  (Luckily, I have good teeth and rarely need serious dental care.)  We all have fears, reasonable and unreasonable, and some are bad enough to impact our lives in a major way, enough that psychologists and neuroscientists have put considerable time and effort into learning how to quell (or eradicate) the worst of them.

In her wonderful book Nerve: Adventures in the Science of Fear, journalist Eva Holland looks at the psychology of this most basic of emotions -- what we're afraid of, what is happening in our brains when we feel afraid, and the most recently-developed methods to blunt the edge of incapacitating fears.  It's a fascinating look at a part of our own psyches that many of us are reluctant to confront -- but a must-read for anyone who takes the words of the Greek philosopher Pausanias seriously: γνῶθι σεαυτόν (know yourself).

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

The body exchange

When we think about our own bodies, we tend to externalize them.  It's subtle, but ponder it for a moment; when I say "this is my hand," where is the "me" who is the hand's owner?  We usually put our "selves" in our heads (or hearts), so the rest of the pieces belong to whoever that "self" actually is.

As support of this, consider the unpleasant possibility of losing a limb, a sense, the ability to walk.  Something huge and devastating.  Even with such a major change, most of us feel that our "self" would remain intact.  Switch brains, though (if such a thing were possible) and you wouldn't be you any more -- there's something about that sense of self that resides there, in what my neurophysiology professor called "the meat machine."

René Descartes's illustration of mind-body dualism

Predictably, the reality may be more complex than that.  In a fascinating experiment run at the Karolinska Institutet of Sweden, researchers used virtual reality headsets to give two friends lying near each other the sense that they'd switched bodies.  In "Perception of Our Own Body Influences Self-Concept and Self-Incoherence Impairs Episodic Memory," by Pawel Tacikowski, Marieke Weijs, and Henrik Ehrsson, which came out in iScience this week, we find out that the sense of who we are is much more intimately connected to our bodies than we might realize.

The researchers did personality assessments prior to the swap.  Each participant ranked both him/herself and the friend on a number of characteristics.  While wearing the headsets, they were asked to re-rate both themselves and their friends -- and across the board, while they were in the body swap they ranked themselves as closer to what they had previously ranked their friend!

Another interesting feature was that both before and after the swap, participants were given memory tests.  They were also asked how convincing the illusion was -- how real it seemed that they were inhabiting their friend's body while the headset was on.  Last, how comfortable were they with the illusion?  Did they find it intriguing, exciting, scary, disorienting?  Curiously, the people who were the most comfortable and curious about being "inside a friend's body" did significantly better on the memory tests, leading to the conjecture that a skew between your bodily awareness and your sense of self can interfere with cognitive activity.

"We show that the self-concept has the potential to change really quickly, which brings us to some potentially interesting practical implications," said study lead author Pawel Tacikowski, in an interview with Neuroscience News.  "People who suffer from depression often have very rigid and negative beliefs about themselves that can be devastating to their everyday functioning.  If you change this illusion slightly, it could potentially make those beliefs less rigid and less negative."

The authors write:

[Our findings extend] previous knowledge in several important ways.  First, it challenges a common assumption that self-concept is relatively fixed over time and emphasizes the role of the body in the continuous construction of our sense of who we are; this role has been largely neglected in past social psychology research.  Second, this result shows that perceptual aspects of the bodily self dynamically shape multiple, abstract beliefs that constitute our conscious self-concept rather than only selected aspects of self-representation that are perceptual, body-related, or implicit.  Third, this finding clarifies that the illusory ownership of another person's body not only modifies attitudes toward this person or toward a social group to which this person belongs but also, and perhaps predominantly, modifies beliefs about the self.

What this immediately made me think of is people with body dysmorphia -- often at the root of not only disorders like anorexia, in which a person who is thin to the point of emaciation looks in a mirror and sees him/herself as overweight, but in trans individuals, who often describe the feeling as "not being in the right body."  It's no wonder both conditions are devastating, and linked to depression and suicidal ideation.  What the Tacikowski et al. study showed is that our sense of self is deeply connected to our own bodies -- and a disconnect between the self and the body has profound cognitive and emotional effects.

Naturally, the next step is to find out what's actually happening in the brain during the illusion.  "Now, my mind is occupied with the question of how this behavioral effect works — what the brain mechanism is,"  Tacikowski said. "Then, we can use this model for more specific clinical applications to possibly develop better treatments."  I'm also curious to find out how long-lasting the effects were.  Did this trigger a long-term change in how the person sees his/her friend?  Or did the change evaporate as soon as the headset was turned off and the participant was "back in your his/her own body?"

No question, though, that it's a fascinating result, and worthy of a lot more inquiry.  It gives some new insight into the age-old "mind-body problem" that has plagued philosophers since the time of Plato.  Perhaps the mind and the body aren't as independent of each other as it seems -- and our sense of self is much more tied to our physical flesh-and-blood presence than was apparent.

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This week's Skeptophilia book recommendation of the week is a brilliant retrospective of how we've come to our understanding of one of the fastest-moving scientific fields: genetics.

In Siddhartha Mukherjee's wonderful book The Gene: An Intimate History, we're taken from the first bit of research that suggested how inheritance took place: Gregor Mendel's famous study of pea plants that established a "unit of heredity" (he called them "factors" rather than "genes" or "alleles," but he got the basic idea spot on).  From there, he looks at how our understanding of heredity was refined -- how DNA was identified as the chemical that housed genetic information, to how that information is encoded and translated, to cutting-edge research in gene modification techniques like CRISPR-Cas9.  Along each step, he paints a very human picture of researchers striving to understand, many of them with inadequate tools and resources, finally leading up to today's fine-grained picture of how heredity works.

It's wonderful reading for anyone interested in genetics and the history of science.

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