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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Aliens in New Zealand

There's a reason that scientists don't put much faith in eyewitness accounts, and it's not just because of hoaxers and liars.

Eminent astronomer Neil deGrasse Tyson tells a story about a policeman who was driving on a winding mountain road at night, and called in to his dispatcher with a frantic account of pursuing a UFO.  The light in the sky, he said, was bright white, and was bobbing and weaving as he followed it.  Nothing natural could move that way, the policeman said.  It had to be a spaceship from another world.

It turned out that the policeman wasn't chasing a spaceship at all, he was chasing... the planet Venus.  It was low over the horizon, and as the policeman maneuvered his car along the winding road, it appeared to move back and forth.  He was so focused on the combination of keeping the "UFO" in sight and not running off the road that he honestly didn't realize the apparent bouncing about was because of his motion, not the "UFO's."

So, as Tyson put it, we need something more than "I saw it."  In science, that simply isn't enough.

Which is why the "eyewitness account" that hit the news last week from a 70-year-old New Zealander is not really carrying much weight with the scientific world.  Alec Newald gave an interview in which he finally made public a claim that in 1989, he was driving from Auckland to Rotorua, and was abducted by aliens...

... for ten days.

"I was like what the hell is going on here?" he said.  "I was driving the car and it felt like a tonne of bricks had landed on me, like someone had poured cement on me.  I felt like I was pushed into the seat of that car.  I was paralyzed, I couldn’t turn the wheel or apply the brakes or do anything."

Newald says he lost consciousness, and woke up in a "cavernous space filled with blue flashing lights."  At first, he thought he'd died and this was the afterlife, although why the afterlife would have blue flashing lights is a bit of a mystery.  Maybe heaven has KMart-style Blue Light Specials, I dunno.

Shortly afterwards, Newald said he became aware that he was basically incorporeal, further supporting his guess that he was in spirit form.  "I was just like a wispy ghost with no form at all," he said.  "I found I could maneuver myself by moving my consciousness forward or sideways."

But that was only the beginning.  Newald felt a "tap on the shoulder," which is itself a little odd as I wouldn't think an incorporeal ghost would have a shoulder to tap.  But he turned, and found himself confronted by a strange sight.

Looking up, I realized we were being approached by three aliens, the tallest of them looking like my escort from earlier on.  The second one was just a little shorter and was male as far as I could tell. The third was smaller, much smaller, and walked ahead of the other two.  He, for want of a better word, was slightly built with a roundish head and rather unusual, squinty eyes which were well-spaced and placed rather lower down than are our own.  He had a very small mouth, but I did not notice any ears or much of a nose.  His physical appearance, however, was of almost no consequence, for I was immediately struck with an almost overpowering feeling of his presence.  I cannot say it was hypnotic, if anything, the opposite. It was as if his energy was being projected and absorbed by my body.

He then was told to step into a machine, which would "build a body" for him -- and that the aliens were trying to modify their own bodies so they could exist on Earth.

Alec Newald's drawing of one of the aliens he saw during his abduction experience

Newald says the aliens kept him for ten days, showing him around the place.  They were entirely friendly, and at the end of the time, he was returned back to Earth, and found himself back in his car on the way to Rotorua, as if no time at all had elapsed.  But despite the fact that this crazy experience had left him back where he started, he didn't find it so easy to deal with.

"It's a very hard pill to swallow," he said.  "Try absorbing that and continue to live your life as if nothing has changed...  Perhaps an even bigger surprise was, with the exception of a few, the more I tried to share this information the harder my life became.  I was ostracized by people you might have expected support from.  In fact, even before I tried to share any of the things I’d learnt, my life started to become more than difficult.  It became impossible to continue on as before."

Okay.  So here's the problem.  Alec Newald might have been abducted by aliens.  I am of the opinion -- and I'm up front about the fact that it is just an opinion, based on what I think is a logical argument but no facts whatsoever -- that life is probably very common in the universe, and chances are, there's a good bit of intelligent life out there, too.  It's possible, but less plausible, that some highly advanced civilization crossed interstellar spaces to Earth and kidnapped a dude in New Zealand for study.

But in order to be confident that this actually happened, scientists and skeptics need more than Mr. Newald's account.  It just doesn't meet the minimum standard for evidence that would be considered a reliable support for a scientific claim.  Note that I'm not saying Mr. Newald is lying; but as Tyson's story of the Venus-chasing policeman shows, our sensory-perceptive and cognitive systems are not exactly 100% reliable.  "Trust your eyes" is not what a skeptic should be saying; closer to the truth is "don't trust anyone's eyes, especially your own."

So unfortunately, I'm not jumping to the conclusion I've seen more than once in media sources that wrote about Alec Newald's claims, that this represents an unshakable support for intelligent alien life visiting the Earth.  I don't know what happened to Mr. Newald -- whether he really did get kidnapped by benevolent extraterrestrials, or he had some kind of dissociative experience, or is conflating a dream with reality in his memory, or is simply making it all up.  What I do know is that this account doesn't change the situation with respect to alien intelligence -- there's just not enough to this claim that it should be taken as proof one way or the other.

***************************

In writing Apocalyptic Planet, science writer Craig Childs visited some of the Earth's most inhospitable places.  The Greenland Ice Cap.  A new lava flow in Hawaii.  Uncharted class-5 rapids in the Salween River of Tibet.  The westernmost tip of Alaska.  The lifeless "dune seas" of northern Mexico.  The salt pans in the Atacama Desert of Chile, where it hasn't rained in recorded history.

In each place, he not only uses lush, lyrical prose to describe his surroundings, but uses his experiences to reflect upon the history of the Earth.  How conditions like these -- glaciations, extreme drought, massive volcanic eruptions, meteorite collisions, catastrophic floods -- have triggered mass extinctions, reworking not only the physical face of the planet but the living things that dwell on it.  It's a disturbing read at times, not least because Childs's gift for vivid writing makes you feel like you're there, suffering what he suffered to research the book, but because we are almost certainly looking at the future.  His main tenet is that such cataclysms have happened many times before, and will happen again.

It's only a matter of time.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]

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 recent 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 couldn't resist.

"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."

**************************************

This week's Skeptophilia book recommendation is from the brilliant essayist and polymath John McPhee, frequent contributor to the New Yorker.  I swear, he can make anything interesting; he did a book on citrus growers in Florida that's absolutely fascinating.  But even by his standards, his book The Control of Nature is fantastic.  He looks at times that humans have attempted to hold back the forces of nature -- the attempts to keep the Mississippi River from changing its path to what is now the Atchafalaya River, efforts in California to stop wildfires and mudslides, and a crazy -- and ultimately successful -- plan to save a harbor in Iceland from a volcanic eruption using ice-cold seawater to freeze the lava.

Anyone who has interest in the natural world should read this book -- but it's not just about the events themselves, it's about the people who participated in them.  McPhee is phenomenal at presenting the human side of his investigations, and their stories will stick with you a long time after you close the last page.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]

Reality, nightmares, and the paranormal

I was giving some thought this morning to why I've turned into such a diehard doubter of paranormal occurrences.  And I think one of the main reasons is because I know enough neuroscience to have very little faith in my own brain and sensory organs.

I'm not an expert on the topic, mind you.  I'm a raving generalist, what some people describe as "interested in everything" and more critical sorts label as a dilettante.  But I know enough about the nervous system to teach a semester-long elective in introductory neuroscience, and even without my native curiosity that keeps me reading about new developments.

This is what prompted a former student of mine to hand me Oliver Sacks's book Hallucinations.  I love Sacks's writing -- The Man Who Mistook His Wife for a Hat and Musicophilia are tours de force -- but this one I hadn't heard of.

And let me tell you, if you are the type who is prone to say, "I know it happened, I saw it with my own eyes!", you might want to give this book a read.

The whole book is a devastating blow to our confidence that what we see,  hear, and remember is reality.  But the especially damning part began with his description of hypnopompic hallucinations -- visions that occur immediately upon waking.  Unlike the more common hypnagogic experiences, which are dreamlike states in light sleep, hypnopompic experiences have the additional characteristic that when you are in one, you are (1) convinced that you are completely awake, and (2) certain that what you're seeing is real.

Sacks describes one of his own patients who suffered from frequent hypnopompic hallucinations.  Amongst the things the man saw were:

• a huge figure of an angel
• a rotting corpse lying next to him in bed
• a dead child on the floor, covered in blood
• hideous faces laughing at him
• giant spiders
• a huge hand suspended over his face
• an image of himself as an older man, standing by the foot of the bed
• an ugly-looking primitive man lying on the floor, with tufted orange hair

Fortunately for him, Sacks's patient is a rational man and knows that what he is experiencing is hallucination, i.e., not real.  But you can see how if you were even slightly inclined to believe in the paranormal, this would put you over the edge (possibly in more than one way).

But it gets worse.  There's cataplexy, which is a sudden and  total loss of muscular strength, resulting in the sufferer falling to the ground while remaining completely conscious.  Victims of cataplexy often also experience sleep paralysis, which is another phenomenon that occurs upon waking, and in which the system that is supposed to re-sync the voluntary muscles with the conscious mental faculties fails to occur, resulting in a terrifying inability to move.  As if this weren't bad enough, cataplexy and sleep paralysis are often accompanied by hallucinations -- one woman Sacks worked with experienced an episode of sleep paralysis in which she saw "an abnormally tall man in a black suit... He was greenish-pale, sick looking, with a shock-ridden look in the eyes.  I tried to scream, but was unable to move my lips or make any sounds at all.  He kept staring at me with his eyes almost popping out when all of a sudden he started shouting out random numbers, like FIVE-ELEVEN-EIGHT-ONE-THREE-TWO-FOUR-NINE-TWENTY, then laughed hysterically."

After this the paralysis resolved, and the image of the man "became more and more blurry until he was gone."

Johann Heinrich Füssli, The Nightmare (1790) [image courtesy of the Wikimedia Commons]

Then there are grief-induced hallucinations, an apparently well-documented phenomenon which I had never heard of before.  A doctor in Wales, W. D. Rees, interviewed three hundred people who had recently lost loved ones, and found that nearly half of them had at least fleeting hallucinations of seeing the deceased.  Some of these hallucinations persisted for months or years.

Given all this, is it any wonder that every culture on Earth has legends of ghosts, demons, and spirits?

Of course, the True Believers in the studio audience (hey, there have to be some, right?) are probably saying, "Sacks only calls them hallucinations because that's what he already believed to be true -- he's as guilty of confirmation bias as the people who believe in ghosts."  But the problem with this is, Sacks also tells us that there are certain medications which make such hallucinations dramatically worse, and others that make them diminish or go away entirely.  Hard to explain why, if the ghosts, spirits, et al. have an external reality, taking a drug can make them go away.

But the psychics probably will just respond by saying that the medication is making people "less attuned to the frequencies of the spirit world," or some such.  You can't win.

In any case, I highly recommend Sacks's book.  (The link to the Amazon page is posted above, if you'd like to buy a copy.)  It will, however, have the effect of making you doubt everything you're looking at.  Not that that's necessarily a bad thing; a little less certainty, and a little more acknowledgement of doubt, would certainly make my job a hell of a lot easier.

Wine, violins, and trusting your senses

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I guess I know too much about neuroscience to trust my own senses.  It's a point I've made before; we get awfully cocky about our own limited perspective, when rightfully we should have remarkably little faith in what we see or hear (or remember, for that matter).  Oh, our perceptions are enough to get by on; we wouldn't have lasted long as a species if our sight and hearing led us astray more often than not.

But the devil is in the details, they say, and in this case it proves remarkably (and perhaps regrettably) true.  What you think your senses are telling you is probably not accurate.

At all.

And the worst part is, it doesn't matter if you're an expert.  It might even be worse if you are.  Not only does your confidence blind you to your own mistakes, at times your expectations about what you're experiencing seem to predispose you to blundering more than an amateur would in similar circumstances.

I first ran into this rather troubling phenomenon last year, when a study came out that indicated that wine experts couldn't tell the difference between an expensive wine and a cheap one -- if they were deprived of the information on the label:

French academic Frédéric Brochet... presented the same Bordeaux superior wine to 57 volunteers a week apart and in two different bottles – one for a table wine, the other for a grand cru. 

The tasters were fooled. 

When tasting a supposedly superior wine, their language was more positive – describing it as complex, balanced, long and woody.  When the same wine was presented as plonk, the critics were more likely to use negatives such as weak, light and flat.

Then Brochet pissed off the wine snobs even worse with a subsequent experiment in which it became apparent that the tasters couldn't even tell the difference between a red and a white wine:

[Brochet] asked 54 wine experts to test two glasses of wine– one red, one white. Using the typical language of tasters, the panel described the red as "jammy' and commented on its crushed red fruit. 

The critics failed to spot that both wines were from the same bottle. The only difference was that one had been coloured red with a flavourless dye.

Now lest you think that this phenomenon only applies to wine snobbery, a study has come out from Claudia Fritz at the University of Paris that shows that the same expert-and-expectation bias can occur with our perceptions of sounds -- when she demonstrated that expert violinists couldn't reliably tell the difference between a Stradivarius and a newly-fashioned modern violin:

“During both sessions, soloists wore modified welders’ goggles, which together with much-reduced ambient lighting made it impossible to identify instruments by eye,” the researchers write. In addition, the new violins were sanded down a bit to “eliminate any tactile clues to age, such as unworn corners and edges...” 

In the concert hall, the violinists were given free reign: They could ask for feedback from a designated friend or colleague, and a pianist was on hand so they could play excerpts from sonatas on the various violins. 

Afterwards, they rated each instrument for various qualities, including tone quality, projection, articulation/clarity, “playability,” and overall quality. Finally, they briefly played six to eight of the instruments and guessed whether each was old or new. 

The results: Six of the soloists chose new violins as their hypothetical replacement instruments, while four chose ones made by Stradivari. One particular new violin was chosen four times, and one Stradivarius was chosen three times, suggesting those instruments were the clear favorites.

You can understand how these results might upset classical violinists, perhaps even more than Brochet's experiment ruffled the feathers of the wine tasters.  Stradivarius, after all, is considered the touchstone for sound quality in a string instrument.

[image courtesy of photographer Håkan Svensson and the Wikimedia Commons]

There are 650 known Stradivari instruments, and their market value is estimated to be in the hundreds of thousands to millions of dollars.  Each.  The idea that a new -- albeit excellent -- violin could compete with a Strad in sound quality is profoundly unsettling to a lot of people.

Reasonably speaking, however, I don't know why it should be (other than the monetary aspect, of course).  Wines and music are both rich sensory experiences, and our appreciation of either (or both) is the result of not only the stimulation of millions of sensory neurons, but the release of a complex broth of neurochemicals that creates a feedback loop with our sense organs, emotional centers, and cognitive processes.  We shouldn't expect that experiencing either wine or music would be a predictable thing; if it was, they probably wouldn't have the resonance they do.

So it's not surprising, really, that our expectations about the taste of a wine or the sound of a violin should change our perceptions.  It's just one more kick in the pants to our certainty, however, that what we see and hear and feel is accurate in its details.  The idea doesn't bother me much, honestly.  Nothing that a little Riunite on ice can't fix.

The stone hand illusion

One of the reasons I trust science is that I have so little trust in my own brain's ability to assess correctly the nature of reality.

Those may sound like contradictions, but they really aren't.  Science is a method that allows us to evaluate hard data -- measurements by devices that are designed to have no particular biases.  By relying on measurements from machines, we are bypassing our faulty sensory equipment, which can lead us astray in all sorts of ways.  In Neil deGrasse Tyson's words, "[Our brains] are poor data-taking devices... that's why we have machines that don't care what side of the bed they woke up on that morning, that don't care what they said to their spouse that day, that don't care whether they had their morning caffeine.  They'll get the data right regardless."

But we still believe that we're seeing what's real, don't we?  "I saw it with my own eyes" is still considered the sine qua non for establishing what reality is.  Eyewitness testimony is still the strongest evidence in courts of law.  Because how could it be otherwise?  Maybe we miss minor things, but how could we get it so far wrong?

A scientist in Italy just knocked another gaping hole in our confidence that our brain can correctly interpret the sensory information it's given -- this time with an actual hammer.

Some of you may have heard of the "rubber hand illusion" that was created in an experiment back in 1998 by Matthew Botvinick and Jonathan Cohen.  In this experiment, the two scientists placed a rubber hand in view of a person whose actual hand is shielded from view by a curtain.  The rubber hand is stroked with a feather at the same time as the person's real (but out-of-sight) hand receives a similar stroke -- and within minutes, the person becomes strangely convinced that the rubber hand is his hand.

The Italian experiment, which was just written up this week in Discover Online, substitutes an auditory stimulus for the visual one -- with an even more startling result.

Irene Senna, professor of psychology at Milono-Bicocca University in Milan, rigged up a similar scenario to Botvinick and Cohen's.  A subject sits with one hand through a screen.  On the back of the subject's hand is a small piece of foil which connects an electrical lead to a computer.  The subject sees a hammer swinging toward her hand -- but the hammer stops just short of smashing her hand, and only touches the foil gently (but, of course, she can't see this).  The touch of the hammer sends a signal to the computer -- which then produces a hammer-on-marble chink sound.

And within minutes, the subject feels like her hand has turned to stone.

[image courtesy of the Wikimedia Commons]

What is impressive about this illusion is that the feeling persists even after the experiment ends, and the screen is removed -- and even though the test subjects knew what was going on.  Subjects felt afterwards as if their hands were cold, stiff, heavier, less sensitive.  They reported difficulty bending their wrists.

To me, the coolest thing about this is that our knowledge centers, the logical and rational prefrontal cortex and associated areas, are completely overcome by the sensory-processing centers when presented with this scenario.  We can know something isn't real, and simultaneously cannot shake the brain's decision that it is real.  None of the test subjects was crazy; they all knew that their hands weren't made of stone.  But presented with sensory information that contradicted that knowledge, they couldn't help but come to the wrong conclusion.

And this once again illustrates why I trust science, and am suspicious of eyewitness reports of UFOs, Bigfoot, ghosts, and the like.  Our brains are simply too easy to fool, especially when emotions (particularly fear) run high.  We can be convinced that what we're seeing or hearing is the real deal, to the point that we are unwilling to admit the possibility of a different explanation.

But as Senna's elegant little experiment shows, we just can't rely on what our senses tell us.  Data from scientific measuring devices will always be better than pure sensory information.  To quote Tyson again:  "We think that the eyewitness testimony of an authority -- someone wearing a badge, or a pilot, or whatever -- is somehow better than the testimony of an average person.  But no.  I'm sorry... but it's all bad."