Visualizing $63 Trillion Of World Debt


If you add up all the money that national governments have borrowed, it tallies to a hefty $63 trillion.


Courtesy of: Visual Capitalist

In an ideal situation, governments are just borrowing this money to cover short-term budget deficits or to finance mission critical projects. However, as Visual Capitalist’s Jeff Desjardins notes, around the globe, countries have taken to the idea of running constant deficits as the normal course of business, and too much accumulation of debt is not healthy for countries or the global economy as a whole.

The U.S. is a prime example of “debt creep” – the country hasn’t posted an annual budget surplus since 2001, when the federal debt was only $6.9 trillion (54% of GDP). Fast forward to today, and the debt has ballooned to roughly $20 trillion (107% of GDP), which is equal to 31.8% of the world’s sovereign debt nominally.


In today’s infographic, we look at two major measures: (1) Share of global debt as a percentage, and (2) Debt-to-GDP.

Let’s look at the top five “leaders” in each category, starting with share of global debt on a nominal basis:

Together, just these five countries together hold 66% of the world’s debt in nominal terms – good for a total of $41.6 trillion.

Next, here’s the top five for Debt-to-GDP:

While only Italy and Japan here are considered major economies on a global scale, the high debt levels of countries like Greece or Portugal are also important to monitor.

In the IMF’s baseline scenario, Greece’s government debt will reach 275% of its GDP by 2060, when its financing needs will represent 62% of GDP.


– A recent IMF report, obtained by Bloomberg

Greece, for example, is continuing along a particularly unsustainable path – and external creditors are getting stingier. Most recently, both the IMF and Greece’s euro-area creditors have demanded for the country to implement a law that automatically introduces austerity measures if a budget surplus of 3.5% of GDP isn’t hit.

While Greece has dismissed such demands as “unacceptable”, the country – along with many others around the globe – will have to accept that constant debt accumulation has eventual consequences.

*  *  *

To get “$63 Trillion of World Debt” in printed form, go to the Kickstarter page now. Deadline: Oct. 31, 2017

from Zero Hedge

Here’s what losing weight does to your body and brain


Special thanks to John Gunstad, Professor with the Department of Psychological Sciences at Kent State University, for speaking with us about his cutting-edge research on how losing weight affects brain function. Following is a transcript of the video.

Here’s what losing weight does to your body and brain.

During the first week you may find it easy to lose weight by simply switching to a healthier diet. But as your metabolism adjusts, you won’t burn as many calories as you used to.

So, losing additional weight will become harder.

Making matters worse, as the fat melts away you’ll start to experience an increase in appetite. After a meal, fat cells release a hormone called leptin into the bloodstream.

This surge in leptin levels signals to your brain you’re full and should stop eating. But with less overall fat, people who lose weight show a measurable dip in leptin.

Brain scans of obese patients who had lost 10% of their body weight revealed less leptin leads to increased activity in regions of the brain that control our desire to eat.

The end result isn’t just an increased appetite, but an even stronger urge to eat fatty, high-calorie foods because your brain is trying to restore the body’s leptin levels to normal.

However, fighting that early impulse to gorge on pizza and donuts is worth it in the long run.

Besides the decreased risk of heart disease, hypertension, high cholesterol and type 2 diabetes, scientists studying overweight people discovered that losing just one pound of body weight reduces four pounds of pressure on knee joints.

Losing excess weight also reduces strain on the blood vessels, increases blood flow to the brain, and boosts overall brain function.

Several studies have shown that people who underwent weight-loss surgery saw an improvement in memory, concentration, and problem-solving skills in as soon as 3 months.

Plus, brain scans indicate that people who lost weight and kept it off for 9 months reacted differently when shown images of high-calorie foods than before they lost weight.

The brain regions that process reward, motivation, and taste didn’t react as strongly, whereas the areas that promote overall self-control had a boost in activity.

So, fighting those cravings early on might make them easier to control later. Turns out — like anything else — losing weight can get easier with practice.

Join the conversation about this story »

from SAI

These 11 Amazon Echo jokes and features show off the company’s unique sense of humor


amazon echo

You probably knew Amazon’s Alexa was smart. But did you know it has a great sense of humor too?

The voice assistant inside the company’s line of Echo smart speakers, Alexa can set timers, play music, order a car, and even read to you at night.

That’s pretty impressive, but a know-it-all assistant could get irritating after awhile. Luckily the whizzes at Amazon decided to lighten up Alexa with a sense of humor.

Alexa’s jokes often veer dangerously close to ones your dad might tell, but at times she can be pretty cheeky too. Amazon also seems to enjoy holidays — just in time for Halloween, it’s added some seasonally spooky jokes.

Here are 11 of our favorite Alexa jokes, spooky and otherwise:

SEE ALSO: I’ve owned an Amazon Echo for over a year now — here are my 19 favorite features

“Alexa, what should I be for Halloween?”

Alexa has several ideas for Halloween costumes. It’ll also suggests going as an Echo or a box of Count Chocula cereal. 

“Alexa, what are you going to be for Halloween?”

“Alexa, what’s your favorite horror movie?”

That’s a clever allusion to Amazon’s own package delivery options. 

See the rest of the story at Business Insider

from SAI

There’s new evidence of how our DNA shapes depression and other disorders like it


sad woman depressed lonely girl

  • Scientists are uncovering promising links between specific parts of our DNA and a range of disorders such as anxiety, depression, and obsessive-compulsive disorder.
  • As with any disease, having certain genes or mutations in those genes doesn’t mean you’ll go on to develop the disorders, but it may play a key role.
  • The research also helps highlight the biological underpinnings of mental illness, something that could help with the development of better treatments.


When you fall and break a bone, an X-ray shows the crack. There’s no equivalent diagnostic for disorders of the brain — a shortfall that’s made it difficult for millions of people with conditions ranging from anxiety to obsessive-compulsive disorder to get treatment.

A spate of new research may change that. In a handful of recent studies, scientists have identified what they believe to be some of the most reliable genetic hallmarks of mental illness, a discovery that would transform our current approach to treating the disorders. If we can better understand the genes that influence psychiatric diseases, we can design treatments that accurately target the part of the brain that they appear to effect.

"Beyond giving us so much data to explore, being able to show that depression is a brain disease, that there is biology associated with it, I think that’s really critical," Roy Perlis, the director of the Center for Experimental Drugs and Diagnostics at Massachusetts General Hospital, told Business Insider in 2016. "These are brain diseases, like any other. They’re not someone’s fault."

LifeProfile DNA Kit 2The latest research suggests that our DNA may play an outsize role in psychiatric disease. As far as diseases go, mental illnesses are among those that are the most likely to be passed down from parent to child, a finding only recently illuminated by decades of research. 

"Genetics plays a very big role in your risk of getting these diseases," Elinor Karlsson, a geneticist at the Broad Institute of MIT and Harvard University, told Business Insider. 

Still, looking at someone’s genome alone will probably never be enough to determine if they’ll go on to develop a psychiatric disease — other factors, including environmental factors like severe stress, play a strong role too. But scientists are discovering more and more clues that suggest that the key to discovering new treatments for mental illnesses will center on a deeper dive into our DNA.

"We need to go after this genetic component," Karlsson said.

In the summer of 2016, Perlis used data from 23andMe to pinpoint 17 genetic variants linked with major depressive disorder. But Perlis and 23andMe aren’t the only ones making progress in this arena. Earlier this month, researchers at the University of Massachusetts and the Broad Institute identified four genes linked to obsessive-compulsive disorder (OCD), a chronic condition characterized by uncontrollable repetitive thoughts and behaviors. 

‘People who have OCD are more likely to have these changes in these genes’

Hyun Ji Noh, a geneticist at the Broad Institute, has read lots of studies showing a link between OCD and genetics. Despite all this promising research, none of the existing papers came to any definitive conclusions about which genes seemed to be tied to the disorder.

So for her latest study, published earlier this month in the journal Nature Communications, she decided to try a different tack.

Instead of just focusing on human DNA, which in the other studies had yielded limited results, she looked at multiple sets of genes — and not just from humans. 

"There are a lot of naturally occurring dog diseases — especially psychiatric diseases — that are very similar to human diseases," Hyun Ji Noh, a geneticist at the Broad Institute and the lead author on the study, told Business Insider. "So to me it was sort of natural to put dog studies in the context of human disease."

alone sad depressed seaNoh’s paper looked at hundreds of genes that had been implicated in psychiatric disease in dogs, mice, and people.

In humans, the researchers found 608 genes. To find out which of these 608 genes was actually tied to OCD, Noh compared what they looked like in hundreds of people with and without the disorder. By the end of the analysis, just four genes emerged that showed up repeatedly in mutated form in people with OCD. 

In these four genes, "a lot of mutations kept showing up for OCD patients but not in the healthy individuals," Noh said.

In other words, these four genes likely play a key role in the biology of the disorder. Still, having a mutation in one of these four genes doesn’t necessarily mean you’ll go on to develop OCD.

"We know people who have OCD are more likely to have these changes in these genes. But this is one of potentially 100 things that will determine if you have OCD," said Karlsson, who also worked on the paper. "It’s complicated," she said.

Chasing ‘depression genes’

Like OCD, researchers say depression is influenced heavily by our DNA. But unlike OCD, it’s fairly common, occurring in an estimated 16.1 million Americans. Current treatments for depression haven’t changed much since the 1950s, and they don’t work for everyone.

So, in an effort to find out more about what exactly causes the illness, researchers published a paper in the summer of 2016 in the journal Nature Genetics in which they pinpointed 17 genetic variations, or tweaks in particular genes, that appear to be tied to major depressive disorder, the most debilitating form of the disease that’s currently the leading cause of disability worldwide.

The researchers got their data from personal genomics company 23andMe. 

Using data from more than 75,600 people who told the company that they’d been clinically diagnosed with depression and more than 231,700 people who reported no history of depression, Perlis and his team were able to identify 17 areas on DNA that appear to be linked with depression. They also found some ties between these areas and those which have been previously identified as possibly playing a role in other psychiatric disorders, such as schizophrenia.

Scientists have been looking for such genetic hallmarks of depression for years. And while some, like a 2013 study in the journal The Lancet and a 2015 paper in the journal Nature, have yielded promising clues, none have been able to spot any precise, reliable genetic markers of the disease.

At least not until now.

"My group has been chasing depression genes for more than a decade without success, so as you can imagine, we were really thrilled with the outcome," Perlis said.

The hope is that identifying these watermarks in our DNA — tiny areas on genes where high amounts of variation tend to occur among individuals — will help us better understand how genetics and behavior interact to influence disorders like depression.

Still, Perlis said, "this is really just the beginning. Now the hard work is understanding what these findings tell us about how we might better treat [these disorders]."

SEE ALSO: Scientists came to a fascinating conclusion after looking at the DNA of thousands of people with depression

Join the conversation about this story »

NOW WATCH: A mysterious ‘hole’ larger than Maryland has reappeared in Antarctica after 42 years

from SAI

5 little-known things that are just deadly as smoking, according to science


tanning bed

Cigarette smoking, one of the least healthy habits out there, is quickly disappearing in the United States.

The rate of American adults who smoke has declined from 42% in 1965 to 15% in 2015.

However, there are a number of risk factors taking its place, many of which stem from people’s growing preference for sedentary, isolated lifestyles.

As smoking makes its exit in the US, here are the risk factors science says to keep an eye on.

SEE ALSO: Loneliness may be a greater public health hazard than obesity — and experts say it’s getting worse


The growth of social media and waning in-person contact has led Former Surgeon General Vivek Murthy to label loneliness a worldwide epidemic. And it could be lethal.

Julianne Holt-Lunstad, a professor of psychology at Brigham Young University, has found in her research that loneliness reduces people’s life spans by the equivalent of smoking 15 cigarettes a day.


Sitting all day increases risk for a raft of different cancers, a 2014 study found.

Researchers included in their meta-analyses — the gold-standard for research — data from four million people involving how often they sat to watch TV, do work, and commute.

Each two-hour increase in sitting time upped people’s risks for colon, endometrial, and lung cancers, regardless of whether they still exercised during the day.

Sleep loss

The Centers for Disease Control and Prevention have called sleep deprivation a public health problem, as some 50 to 70 million people in the US have sleep or wakefulness disorder.

Professor Valery Gafarov, of the World Health Organization, noted in 2015 that insufficient sleep raises the risk of stroke and heart attack to similar degrees as regular cigarette use.

"Poor sleep should be considered a modifiable risk factor for cardiovascular disease along with smoking, lack of exercise, and poor diet," he said.

See the rest of the story at Business Insider

from SAI

In 1987, former Apple CEO John Sculley launched a video depicting the computer of the future — and people were furious


John Sculley

• In 1987, Apple came out with a concept video that showed a hypothetical computer of the future.

• The video touched upon numerous upcoming technological advances, including voice technology, tablets, and videoconferencing, to name a few.

• But the public wasn’t having it. "People said, ‘Well, this is absurd,’" former Apple CEO John Sculley told Business Insider.

It was a glimpse into the future, but people weren’t ready.

Former Apple CEO John Sculley had first teased the idea of a futuristic computer app in his 1987 autobiography "Odyssey." That same year, Apple released a series of concept videos promoting the idea of "The Knowledge Navigator." The technology would help people search through a large hypertext network using software agents.

The idea came about in the wake of Steve Jobs’ 1985 departure from the company he founded. John Sculley, who succeeded Jobs as Apple’s CEO, knew that the company had to continue to look to the future.

Sculley told Business Insider that, around that time, Apple fellow Alan Kay approached him with a suggestion: look to the MIT Media Lab for inspiration.

Sculley agreed, and the ensuing collaboration resulted in an imagining of what personal computers might look like decades into the future. 

Apple Knowledge NavigatorSet in 2007, the resulting 1987 video followed around an environmental science professor at Berkely juggling everything from preparing a lecture to buying a birthday cake for his father.

To get it all done, he relies on his digital personal butler — the bowtie-wearing, hypothetical grandfather of modern assistants like Siri, Cortana, Alexa, Bixby, and Google Assistant.

During the nearly six-minute vignette, the professor videoconferences with a colleague, researches journal articles on deforestation in the Amazon, and updates his busy schedule, all on one touch screen tablet.

"At the time we came out with it, it was incredibly controversial," Sculley said. "People said, ‘Well, this is absurd.’"

Sculley, who now is working to revolutionize healthcare as the chairman of the startup RxAdvance, said his lack of an engineering degree didn’t help matters back then.

"’How can this guy who’s not an engineer be telling us what technology is going to be looking like years from now?’" he said. "But it wasn’t my technology. It was Alan Kay and all these incredibly talented people at MIT."

Sculley said the fact that many elements of the video have become reality is a reflection of the "exponential rate of change" the tech world has experienced.

"All of these things which we take for granted today, we were being criticized for saying this was what the world was going to look like," he said.

Watch the video here:

If you are a current or former Apple employee with a story to share, email

Correction, October 29, 2017: A previous version of this article incorrectly stated that George Lucas directed the "Knowledge Navigator" video. Randy Field directed the video with Kenwood Group in San Francisco.

SEE ALSO: Former Apple CEO John Sculley explains why Steve Jobs was the best recruiter he ever met

Join the conversation about this story »

from SAI

Remember Your Dreams by Stating Your Intention

Image credit: Pixabay

Remembering your dreams after they happen, or being aware you’re in a dream while you’re having it can be fun, but not exactly easy to do.

Science Alert reports that only about half of us have been able to realize we’re in a dream while it’s happening, and only a fourth of people actually report having lucid dreams frequently. However, if you want to remember your dreams researchers have come up with a technique that might work for you. Their work was recently published in Dreaming.


Researchers looked at a few different processes that are thought to help with lucid dreaming. The front-runner in the group was a technique called MILD (mnemonic induction of lucid dreams).

The idea behind the technique is that you repeat the phrase “The next time I’m dreaming, I will remember that I’m dreaming” while you’re awake. While 17% of participants reported having lucid dreams when they did some of the other techniques, those using MILD reported a whopping 46% success rate.


There’s still a good chance it won’t work, but of the options out there this was the best bet.

By repeating the phrase before you head off to dreamland, you’re creating the intention in your mind that you will, in fact, remember your dreams. That could lead to a lucid dream, say researchers.

Even better, those that used this technique reported not feeling more tired the next day, unlike some of the other techniques tested, such as waking yourself mid-dream, that made participants feel tired the following day.


A 46% success rate certainly isn’t a guarantee that it will work for you, but if you’re on the quest for lucid dreams, it could be worth a try.

from Lifehacker

Why Some Drinks Seem to Make Hangovers Worse 

Image credit: Pexels

Hangovers are horrible. No one wants to get them, but the only way to avoid them entirely is to avoid drinking, which isn’t exactly a fun proposition for those who would like to have a few cocktails either.

At its core, a hangover is most often caused by dehydration, so it can be a good idea to drink as much water as you can before, during, and after that big party where drinks are being served. However, the type of alcohol you choose to drink can also play a role in how hungover you are the next day.


A Dutch study discovered that darker alcohol tended to make college students more hungover the next day than lighter alcohol. The reason is that when the alcohol is fermented it creates chemicals called congeners (and alcohol). The congeners help make for some of the interesting flavors you find in darker booze like red wine and whiskey, but they’re also responsible for rougher hangovers.

When something is filtered a lot, some of those congeners get removed as well. So, something like Smirnoff, which is distilled 10 times might leave you better off than another vodka that was only distilled four times. There’s also an argument out there for avoiding super sugary or bubbly mixers, which have both been proven to make that hangover come a bit faster as well.


In truth, the only way to truly avoid a hangover is to just not drink. However, when you’re given the choice between whiskey shots or vodka shots, there’s a decent argument for going for the lighter-colored booze.

Worth noting, the same study discovered that liquor, in general, is more likely to cause a handover than a glass of wine or beer, in part due to their higher alcohol concentrations. I could have told you that from my own personal “research,” but it’s still good to know that science backs me up.

from Lifehacker

Why Do People See Ghosts?


You live and then you die and then you rot in a hole—or so say the elites, with their glasses, and their PhDs in neuroscience. This bummer reality has never appealed much to Americans, 72% of whom believe in some kind of afterlife. It’s a comparatively rarer, though still sizable, breed of American who believe in some spectral middle ground, in which, instead of rotting or going to hell, you float around and freak out your kids, or the new residents of the house where you were brutally murdered a hundred years ago.

According to Pew Research Center, close to one-fifth of Americans believe they’ve seen a ghost—a somewhat surprising statistic, given all the other ancient beliefs we’ve mostly jettisoned (bloodletting, for instance, has largely fallen out of vogue). For this week’s Giz Asks, we reached out to a number of psychologists and neuroscientists to figure out why this might be—and in the process learned that, given the number of ways our brain has of tricking us into seeing things, it’s a wonder that that statistic isn’t higher.

Christopher French

Founder of the Anomalistic Psychology Research Unit at Goldsmiths, University of London

Most of the time, when people think they’ve had a ghostly encounter, they haven’t necessarily actually seen something. Very often you’ll find that what people are referring to is a bit vaguer than that—a very strong sense of presence, for instance. Bereaved people might think that they smell the perfume that the deceased used to wear, or the tobacco they used to smoke.

People tend to assume, when you suggest that maybe they were hallucinating, that you’re saying that they’re crazy, and this just isn’t true—hallucinations are much more common amongst the non-clinical population than is generally appreciated. We can all hallucinate under appropriate conditions.

One of the phenomena that we’re particularly interested in is something called sleep paralysis. In its most basic form, sleep paralysis is very common. Estimates vary, but typically it’s estimated that about 8% of the general population suffer from basic sleep paralysis at least once in their lives, and a couple of groups—psychiatric patients and students—show it at a much higher rate.

What I mean by basic sleep paralysis is: You’re half awake and you’re half asleep—either going into sleep, or maybe coming out of it—and you get a period of temporary paralysis. It typically lasts a few seconds before you snap out of it. Most of the time it’s not a big deal—it’s a little bit disconcerting, that’s all.

For a smaller percentage of people, you get associated symptoms that can make for a much scarier experience—typically, a very strong sense of presence. Even if you can’t see or hear anything in the room with you, you get a very strong sense that there is something there. You might actually also hallucinate; you might hear voices, or footsteps, or mechanical sounds, or you might see dark shadows moving around the room, or lights, or monstrous figures, or shadow people. You might get tactile hallucinations—you might feel as if you’re being held, or you might feel someone breathing on back of your neck. And bear in mind that throughout all of this, you can’t actually move.

So it’s not too surprising that lots of people who have this experience, if they’ve never heard of sleep paralysis as a scientific and medical concept, end up reaching for some kind of supernatural interpretation. And because it’s such a common experience, you only need a small percentage of people who are having sleep paralysis to go for those kinds of supernatural interpretations.

Michael Nees

Assistant Professor, Department of Psychology, Human Factors, Perception and Cognition Lab, Lafayette College

Our phenomenological experiences of the world—the things we believe we see and hear—are actively constructed from limited and incomplete inputs from the physical world. The light that falls upon our eyes and the sound waves that reach our ears often could have resulted from multiple possible physical sources. For example, a vaguely humanoid object in the corner of a dark room could be a person or a ghost, but it could also just be a jacket hanging on a coat rack. To resolve these ambiguities, we actively construct an internal, mental version of the physical world that reflects our own biases and expectations. Sometimes our perceptions do not reflect accurate representations of the physical world. “Pareidolia” is the name for a common category of misperceptions that occur when a random (i.e., inherently meaningless) perceptual experience is interpreted to have meaning. A common version of pareidolia is perceiving human faces in random configurations of physical objects; a classic example is when people claim to see the face of Jesus in a piece of toast.

Some researchers have suggested that we may be biased toward perceiving ambiguous stimuli as human or human-like, because detecting other human beings in our presence has adaptive value—meaning that, from an evolutionary perspective, other people are especially important stimuli for us to notice. According to this argument, a false alarm (mistakenly perceiving a random, inanimate object—perhaps momentarily—as human) is less harmful than a miss (failing to notice another actual human in one’s presence), thus, when faced with uncertainty, our perceptual systems are calibrated to be more likely than not to register an object as human.

There is some research to indicate that people who are prone to paranormal beliefs are especially likely to attribute human characteristics to ambiguous stimuli, and researchers have suggested that a spooky context or the suggestion of a paranormal situation can prime people to be more likely to interpret ambiguous stimuli as ghosts or poltergeists.

Neil Dagnall and Keith Drinkwater

Neil Dagnall is Reader in Applied Cognitive Psychology at Manchester Metropolitan University, researching anomalous psychology and cognitive psychology; his lab is undertaking several projects centering on belief in the paranormal



Ken Drinkwater is Senior Lecturer at Manchester Metropolitan University who studies paranormal belief

The survival hypothesis proposes a disembodied consciousness (soul) survives bodily death. Seeing ghosts in this context confirms belief in life after death and produces reassurance.

Other explanations draw on environmental factors, such as electromagnetic fields and infrasound. Canadian neuroscientist Michael Persinger demonstrated that the application of varying electromagnetic fields to the temporal lobes of the brain could produce haunt-like experiences (perception of a presence, feeling of God, sensation of being touched, etc.).

Haunt-like perceptions can also arise from reactions to toxic substances. Albert Donnay (Toxicologist) hypotheses that prolonged exposure to a range of substances (carbon monoxide, formaldehyde, pesticide, etc.) can produce hallucinations consistent with haunting. Similarly, Shane Rogers (Associate Professor of Civil & Environmental Engineering) reported that fungal hallucinations caused by toxic mould could stimulate haunting-related perceptions.

Professor Olaf Blanke recently demonstrated that haunt-like illusions could arise from perceptual disorientation. Specifically, conflicting sensory-motor signals. Blindfolded participants performed hand movements in front of their body. A robot imitated the moments in real time by harmoniously touching the participants’ backs. The synchronized movement of the robot allowed participants to adapt to spatial discrepancy. However, temporal delay between participant’s movement and the robot’s touch produced disorientation accompanied by strong feeling of a presence.

Terence Hines

Professor of neurology at Pace University and the author of Pseudoscience and the Paranormal

The human brain has evolved to find patterns. If you’re in the wilderness, and you hear something behind you, it’s way better to think that it’s really a lion or a sabertooth tiger sneaking up on you—to attribute that sound to some agency, something that has purpose. Because if it does have purpose, and you run away, you’re better off. And if it’s just random noise and you run away, there’s no foul, it doesn’t really cost you anything. So we’ve evolved to experience what neuroscientist types call false positives. It’s better to be safe than sorry.

[Another explanation] involves expectations, and there a couple of lovely demonstrations of this effect. Some years ago, for a term project, one of my students took some people to a local graveyard. In one condition, people were taken to a particular grave and told, this is the grave of some old guy who died at 72 of natural causes. Nothing weird about it. This is late at night, midnight. And they would ask: what do you feel? Are you getting any sensations? And people said well, no, not really. And then in the other condition they took people to the same grave at about the same time, late at night, and said it was the grave of a teen girl who died tragically—she’d killed herself after her boyfriend left her, and she’s said to haunt this grave at midnight on the night in question, and this is the anniversary of her suicide. People freaked out. They saw her, they heard her—and it was all due to expectations. I’m not saying that the folks who experienced the ghost of this non-existent teenage girl were lying, or crazy, or hysterical—they weren’t. Their brain was just doing what brains do; they were using information they were given, which turned out to be incorrect.

Tapani Riekki

Cognitive neuroscientist, Department of Psychology and Logopedics, Faculty of Medicine, University of Helsinki

The key thing seems to be interpretation. We know from various studies that our information processing is not “bottom-up”—we don’t just see/hear/feel our environments. Instead, our perception of reality is a complex interplay between bottom-up and top-down processes. Top-down processes refer to the expectations, beliefs, and context that shape our perceptions and influence our interpretations. Even the basic bottom-up processes are not exact copies of reality but approximations shaped by context. How we experience our surroundings is a complex simulation of our mind that leaves a lot of space for interpretation and quirks.

Frank McAndrew

Cornelia H. Dudley Professor of Psychology at Knox College and an elected Fellow of the Association for Psychological Science

Seeing ghosts may be triggered by the “agency-detection mechanisms” proposed by evolutionary psychologists.

These mechanisms evolved to protect us from harm at the hands of predators and enemies. If you are walking down a dark city street and hear the sound of something moving in a dark alley, you will respond with a heightened level of arousal and sharply focused attention and behave as if there is a willful “agent” present who is about to do you harm. If it turns out to be just a gust of wind or a stray cat, you lose little by overreacting, but if you fail to activate the alarm response and a true threat is present, the cost of your miscalculation could be high. Thus, we evolved to err on the side of detecting threats in such ambiguous situations.

In other words, if an individual believes that an encounter with a ghost is a possibility, then ghosts may become the explanation that gets used to resolve uncertainty.

A recent study by Kirsten Barnes & Nicholas Gibson (2013) explored the differences between individuals who have never had a paranormal experience and those who have. They confirmed that experiences of supernatural phenomena are most likely to occur in threatening or ambiguous environments, and they also found that those who had paranormal experiences scored higher on scales measuring empathy and a tendency to become deeply absorbed in one’s own subjective experience.

Benjamin Radford

Benjamin Radford, M.Ed., is a Research Fellow with the Committee for Skeptical Inquiry, a non-profit educational organization based in Buffalo. He has researched ghostly and “unexplained” phenomenon for nearly 20 years and is author of several books on the topic, including “Investigating Ghosts,” out this fall.

When researching ghostly phenomena one of the first things you realize is that often “ghost” is simply a convenient (if sloppy) label for “an experience someone doesn’t understand.” Reports of full-bodied apparitions (the kind you might see at Disneyland’s Haunted Mansion, for example) are very rare. Instead you find that many “ghostly” experiences are much more ambiguous: odd smells or sounds, a feeling of being watched, temperature variations, animals acting up, and so on. Even such mundane experiences as losing your keys can be—and have been—chalked up to the doings of a mischievous resident spirit.

Because there’s such a wide variety of experiences attributed to spirits, there’s no single blanket explanation for all ghost reports. Some can be caused by mild hallucinations—I’m not talking about over-the-top, full-on wild LSD-type hallucinations of flying pink elephants, but instead much more common and subtle tricks of the eye and mind, especially that might occur late at night. The human brain is wonderful but also fallible, and we don’t always perceive and interpret the world around us correctly—and because many “ghostly” experiences are small and fleeting (not the huge and obvious kind depicted in horror films), it’s easy to wonder if an odd sound or light is mysterious. This leads to the second common factor as to why people believe they’re experiencing ghosts: usually they’re influenced by pop culture ideas about what ghosts are and how they act. People watch TV shows like Ghost Hunters (now past its tenth season of not finding ghosts) and are influenced by those shows in terms of what psychologists call priming. Our expectations often guide our perceptions and interpretations, and thus we often see or hear what we expect to see—sometimes even if it’s not there. The psychological reasons behind why people claim to (or believe that they see) ghosts is well understood—and that’s true whether ghosts exist or not!

Do you have a question for Giz Asks? Email us at

from Gizmodo