The electric landscape

In his remarkable TED Talk "Can We Create New Senses for Humans?," neuroscientist David Eagleman describes the concept of the umwelt -- the part of the available stimulus space sampled by a particular animal's senses.  A simple example is the thin slice of the electromagnetic spectrum our eyes are sensitive to -- the familiar ROYGBIV of the rainbow.  There's plenty of electromagnetic radiation outside of that slice; gamma rays, x-rays, ultraviolet light, infrared light, microwaves, and radio waves are all ordinary photons, just like visible light is.  It's just that our eyes aren't sensitive to those frequencies, so they're outside of our umwelt.

The umwelt also has to do with the relative weighting of senses; how big a part of our sensory world a particular experience constitutes.  Most humans have a sense of smell, but my dogs live in a far richer olfactory world than I do.  But even how those inputs are utilized -- i.e., what kind of information they provide for making sense of the world -- can vary greatly.  Bats and dolphins use hearing in much the same way as we use our eyes, creating "sonic landscapes" of the objects around them.  What's kind of amazing, though -- and one of the main points of Eagleman's talk -- is that humans can train their brains to use other "peripherals" (as he calls them) to learn about the world, such as blind people who have learned to navigate the space around them by making clicking noises and listening for echoes from nearby obstacles.

It's always been fascinating to me to consider how the world would look to a night-flying echolocating bat.  Do they "see" their world through their ears and auditory cortex?

The topic of how other animals perceive their worlds -- and how different it could be from what we experience -- comes up because of a paper this week in the journal Nature about how elephantnose fish (Gnathonemus petersii), which live in murky streams in west and central Africa where eyesight doesn't serve much purpose, develop their visual picture of the world (including locating prey) using electric fields.  And not only do they gain information by creating and sensing electrical signals, they enhance those pictures using the signals created by nearby members of their species, making them one of the only known animals that relies on collective signal production and sensing.

Gnathonemus petersii [Image is in the Public Domain]

"Think of these external signals as electric images of the objects that nearby electric fish automatically produce and beam to nearby fish at the speed of light," said Federico Pedraja of Columbia University, who headed the study. "Our work suggests that three fish in a group would each receive three different "electrical views" of the same scene at virtually the same time."

The elephantnose fish's capacity for working in groups is a little like humans out on a search at night with flashlights.  One person with one flashlight would have a small illuminated field of view, but if there were twenty people it would go much faster, not only because of greater manpower, but because each person wouldn't be restricted to what is revealed by only their own flashlight beam.  Just as with twenty different flashlights in the night rather than a single one, in the case of elephantnose fish, the electrical fields produced by their neighbors clarify the picture they all receive.

"In engineering it is common that groups of emitters and receivers work together to improve sensing, for example in sonar and radar," said Nathaniel Sawtell, who co-authored the study.  "We showed that something similar may be happening in groups of fish that sense their environment using electrical pulses.  These fish seem to 'see' much better in small groups...  [They] have some of the biggest brain-to-body mass ratios of any animal on the planet.  Perhaps these enormous brains are needed for rapid and highly sophisticated social sensing and collective behavior."

To return to my original point -- how would the world look to an elephantnose fish?  Surely nothing like what we see.  Some sort of topography of electrical field strength, perhaps, creating an image of the obstacles they have to maneuver around, the prey they seek, and the predators they need to avoid.  But really, there's no way to know.  We're all trapped within our own umwelt.  I can't even imagine what the world is like for my dogs, who are a great deal more similar to me than these fish are.

To perceive the world like another living being does, you'd not only have to come equipped with their sensory systems, but put the information together using their brains.  We can only speculate, with all the inevitable biases that come from being locked in our own ways of knowing.  But this study did at least give us a hint of how different the world could appear -- if we were odd little fish living in muddy African rivers.

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

The ghost in the machine

One of my reasons for doubting a lot of reports of the paranormal is because, to quote Neil deGrasse Tyson, we are poor data-taking devices.  We have, he says, "all sorts of ways of getting it wrong."

The problem is, our brain doesn't agree with that most of the time.  Of course what we're seeing and hearing is real.  Not only is it real, we're seeing and hearing everything there is to see and hear.  We can't possibly be missing something, or sensing something that isn't there.  So if we have an experience outside of the normal realm, it must reflect reality, right?

Of course right.

But a study at the École Polytechnique Fédérale de Lausanne in Switzerland has shown conclusively that it's just not so.  It doesn't take much to fool us, and fool us so convincingly that our brains can't come up with any other explanation but that there's something supernatural happening... even if those brains already knew that they were part of an experiment, and understood how it was being done.

Olaf Blanke, a neuroscientist at ÉPFL, has led a team to create a ghost illusion so real that several participants asked to quit the study because they were so freaked out.  It was done quite simply -- no electrodes or any sort of elaborate apparatus needed.

[This "ghost photo" was created by one of my Critical Thinking students, Nathan Brewer, as part of a project to illustrate how easy it is to generate a convincingly creepy paranormal photograph using PhotoShop.  Not bad, eh? (used with permission)]

What they did was to have blindfolded participants move their hands, while a robotic arm behind them touched them on the back, moving the same way at the same time.  No problem there; the brain quickly figured out what was going on.

But then, they introduced a half-second delay into the proceedings -- so that the robotic arm was a little offset from the movement of the person's real arm.  And this created a sense of an "unseen presence" behind them so realistic (and unsettling) that several participants asked the researchers to stop after three minutes because the sensation was "unbearable."  One participant said he was convinced that there was not just one "ghost" behind him, but four!

"Our experiment induced the sensation of a foreign presence in the laboratory for the first time," Blanke said.   "It shows that it can arise under normal conditions, simply through conflicting sensory-motor signals.  The robotic system mimics the sensations of some patients with mental disorders or of healthy individuals under extreme circumstances.  This confirms that it is caused by an altered perception of their own bodies in the brain."

Which is fascinating, even if it punches further holes in our sense of seeing and interpreting everything correctly.

Now, understand, there are two things I am not saying, here: (1) that all paranormal experiences can be explained by failures in our perceptive or cognitive equipment; and (2) that it's impossible that ghosts (and other such entities) exist.  In my opinion, the jury is very much still out on what's behind experiences of the paranormal in general, and I am reluctant to make the jump that because some of them are misinterpretations or hoaxes, they all are.

What this experiment points out, though, is that anecdote isn't enough.  We're suggestible, easily confused, and bring our own biases into whatever we experience.  If a little touch from a robotic arm on the backs of people who knew they were part of an experiment on perception is sufficient to generate an unshakeable sensation of being in the presence of a ghost, how can we trust stories of the "I was in the room, and then I sensed there was someone else in there with me" variety?

Admittedly, it could well be that there are ghosts, and an afterlife, and so on.  I've seen no convincing evidence of it, and lots of non-convincing evidence, and all too many out-and-out hoaxes and falsehoods.  But could it be?  Sure.

On the "plus" side are (literally) thousands of first-hand accounts, including cases where the claimant has no obvious reason to lie and no other explanation is forthcoming.  On the "minus" side, any bits of hard evidence are equivocal at best (whatever people like Dean Radin might say about it), and there are a couple of convincing non-supernatural possibilities that could account for at least some of those claims.  So at the moment, my position is "I don't know."  I'm going to wait for either scientifically reliable evidence, or else my own death, at which point I'll find out for sure one way or the other.

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

I don't often recommend historical books here at Skeptophilia, not because of a lack of interest but a lack of expertise in identifying what's good research and what's wild speculation.  My background in history simply isn't enough to be a fair judge.  But last week I read a book so brilliantly and comprehensively researched that I feel confident in recommending it -- and it's not only thorough, detailed, and accurate, it's absolutely gripping.

On May 7, 1915, the passenger ship Lusitania was sunk as it neared its destination of Liverpool by a German U-boat, an action that was instrumental in leading to the United States joining the war effort a year later.  The events leading up to that incident -- some due to planning, other to unfortunate chance -- are chronicled in Erik Larson's book Dead Wake, in which we find out about the cast of characters involved, and how they ended up in the midst of a disaster that took 1,198 lives.

Larson's prose is crystal-clear, giving information in such a straightforward way that it doesn't devolve into the "history textbook" feeling that so many true-history books have.  It's fascinating and horrifying -- and absolutely un-put-downable.

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

The ghost in the machine

One of my reasons for doubting a lot of reports of the paranormal is because, to quote Neil deGrasse Tyson, we are poor data-taking devices.  We have, he says, "all sorts of ways of getting it wrong."

The problem is, of course, that our brain doesn't agree with that, most of the time.  Of course what we're seeing and hearing is real.  Not only is it real, we're seeing and hearing everything there is to see and hear.  We can't possibly be missing something, or sensing something that isn't there.  So if we have an experience outside of the normal realm, it must reflect reality, right?

Of course right.

But now, a study at the École Polytechnique Fédérale de Lausanne in Switzerland has shown conclusively that it's just not so.  It doesn't take much to fool us, and fool us so convincingly that our brains can't come up with any other explanation but that there's something supernatural happening... even if those brains already knew that they were part of an experiment, and understood how it was being done.

Olaf Blanke, a neuroscientist at ÉPFL, has led a team to create a ghost illusion so real that several participants asked to quit the study because they were so freaked out.  It was done quite simply -- no electrodes or any sort of elaborate apparatus needed.

[This "ghost photo" was created by one of my Critical Thinking students, Nathan Brewer, as part of a project to illustrate how easy it is to generate a convincingly creepy paranormal photograph using PhotoShop.  Not bad, eh?  (used with permission)]

What they did was to have blindfolded participants move their hands, while a robotic arm behind them touched them on the back, moving the same way at the same time.  No problem there; the brain quickly figured out what was going on.

But then, they introduced a half-second delay into the proceedings -- so that the robotic arm was a little behind the movement of the person's real arm.  And this created a sense of an "unseen presence" behind them that several participants asked the researchers to stop after three minutes because the sensation was "unbearable."  One participant said he was convinced that there was not just one "ghost" behind him, but four!

"Our experiment induced the sensation of a foreign presence in the laboratory for the first time," Blanke said.  "It shows that it can arise under normal conditions, simply through conflicting sensory-motor signals.  The robotic system mimics the sensations of some patients with mental disorders or of healthy individuals under extreme circumstances.  This confirms that it is caused by an altered perception of their own bodies in the brain."

Which is fascinating, even if it punches further holes in our sense of seeing and interpreting everything correctly.

Now, understand, there are two things I am not saying, here:  (1) that all paranormal experiences can be explained from this exact phenomenon; and (2) that it's impossible that ghosts (and other such entities) exist.  What this experiment points out, though, is that anecdote isn't enough.  We're suggestible, easily confused, and bring out own biases into whatever we experience.  If a little touch from a robotic arm, on the backs of people who knew they were part of an experiment on perception, is sufficient to generate an unshakeable sensation of being in the presence of a ghost, how can we trust stories of the "I was in the room, and then I knew there was someone else in there with me" variety?

But admittedly, it could well be that there are ghosts, and an afterlife, and so on.  I've seen no convincing evidence of it, and lots of non-convincing evidence, and all too many out-and-out hoaxes and falsehoods.  But could it be?  Sure.

At the moment, though, I'm going to wait for either scientifically reliable evidence, or else my own death, at which point I'll find out for sure one way or the other.