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Brain Candy
03 February

When it comes to optical illusions, humans aren't the only suckers. Animals fall prey to plenty of the same illusions that we do.

But sometimes, their judgment is more accurate than ours. Scientists have discovered one illusion that doesn't work on chimpanzees, even though it reliably misleads people. The way this illusion tricks us but fails to dupe our closest relatives might reveal how we differ in making sense of the world around us.

The illusion in question featured in a recent experiment conducted on chimpanzees and humans. Called the fat face illusion, it happens when we see an image of two identical faces, one hovering above the other. The face on the bottom appears to be fatter than the one on top.

(image) Fat face illusion. Source: i-Perception

This trick closely resembles the Jastrow illusion, in which two arcs are stacked one above the other. The top arc seems smaller, though in reality they're identical. It seems that we misjudge the size of the top arc because we're comparing its lower right corner with the bottom arc's upper right corner.

(image) Image: Fibonacci via Wikimedia Commons, CC BY-SA 3.0

Masaki Tomonaga, a researcher at Kyoto University, wanted to find out how similar these illusion really are. He and his team presented them both to humans and chimpanzees at the Primate Research Institute in Aichi, Japan.

The chimps and people had to view faces and shapes on a computer screen, one above the other, and click on the thinner or narrower one of each pair. Many pairs really did have objects of different sizes. But in some cases, the arcs or faces were actually identical.

When shown twin arcs, both species made the same mistake. They were more likely to think the top arc was smaller than the bottom one, showing that chimpanzees and people are both susceptible to the Jastrow illusion.

But when it came to judging faces, a difference emerged between humans and our simian relatives. When viewing identical human or chimpanzee visages, people tended to think the bottom face was fatter. As expected, they'd been fooled by the fat face illusion. The chimps, on the other hand, had no bias for the top or bottom face, indicating that the illusion holds no sway over them.

(image) Image: Masaki Tomonaga (2015).

The chimps' ability to see one illusion but not the other suggest that the fat face illusion could be a distinct phenomenon and not just a case of the Jastrow illusion.

For humans to see the fat face illusion, we need to recognize that we are looking at a face in the first place. Scientists discovered in an earlier experiment that if we've got a face-like outline to guide us, we can perceive the illusion even in line drawings of faces, faces with scrambled features and empty faces with no eyes, noses or mouth.

Chimps may rely less on outer contours to recognize a face than people do, noted Tomonaga, who published the findings December 14 in the journal i-Perception. This could explain why the fat face illusion doesn't work on them.

We know that chimpanzees have complex social lives, and that it's important for them to be able to recognize faces, as in people. Scientists have seen that faces quickly capture chimpanzees' attention. But chimps' brains might not approach faces quite the same way as ours.

"The results of the present experiment may suggest that the basic-level processing of the face in chimpanzees is different from humans," Tomonaga concluded.

Brain Candy
02 February

If you're about to sit an exam, have a spare pencil in case the first one breaks. If you're going to ride the subway, know which lines you could transfer to if there are delays or construction on your first choice. If you're going to start a business, have some savings you can fall back on in case monogrammed cat sweaters aren't as popular as you thought.

It seems like good sense to always have a backup plan. We use them for small goals, like getting from one neighborhood to another, and big ones like figuring out our careers.

But if you've got a backup plan for every move you make, you might not be doing yourself any favors. Sometimes, having a plan B might just complicate what we're trying to do.

"People may often make a mistake when it comes to backup plans," said Christopher Napolitano, a psychologist at the University of Zurich in Switzerland. "When backup plans fail it's often because people don't think about…how a backup plan might distract them when they're in the middle of working towards their goal."

In his research, Napolitano is seeing that, in some cases, our backup plans can actually make us less successful. Fortunately, there are a few steps we can take to avoid investing in a backup plan that will only slow us down.

Flop or ace in the hole?

Simply having a backup plan changes how you pursue your goal, as well as how likely you are to meet it, Napolitano and his colleague Alexandra Freund argued in a recent paper in the January volume of Perspectives on Psychological Science.

Depending on the situation, this can help or hinder us. "We're not saying that backup plans are always bad," Napolitano said. "We've all had experiences where it's been great having this backup plan in your back pocket."

Backup plans give us a safety net if our intended course of action fails; if you drive over a nail, having another tire ready to go clearly gives you a better shot at reaching your destination. Backup plans can also make our ambitions seem a little more attainable. "A lot of people say that making a backup plan gives them the courage or the support that they need to start pursuing a difficult goal," Napolitano said.

But sometimes, just having a backup plan in the wings takes work; Imagine a photographer who packs so many extra lenses that he's slowed down by his heavy bag.

And then there are times where having a plan B can sap your motivation to stick with plan A. Napolitano and his colleagues are interested in how contingency plans can backfire. "What happens when you have a backup plan available and your plan A starts to falter?" he said. "Do you start looking at your plan B, does it distract you, do you disengage from plan A earlier than you would have if you didn't have a backup plan?"

The researchers are conducting a few experiments to find out. In one, people must lob balls into a trashcan after a few practice tosses. They have to start by using ping pong balls, but can switch over to tennis balls at any time, which require a slightly modified throwing approach.

If people rely too heavily on the backup plan and switch at early signs of failure, they likely end up doing worse with either type of ball. "The more a person practices their backup plan throwing…the more distracting it is, and the more likely they are to switch to the backup plan ball and the worse they do," Napolitano said. "You have to kind of recalibrate how you throw so you miss the first few throws, but you also have this distraction where you do poorly before you switch."

Backup plans can even distract us to the point of sabotaging our interests. Napolitano and his team have also been tracking freshmen at the University of Zurich, who must sit a difficult exam if they wish to continue studying psychology. The undergrads reported what their backup plan was if they failed the psychology exam, and how much it preoccupied them.

The more the students thought about their backup plan, the worse they did on the test. And those people thought a lot about switching to a less taxing major did particularly poorly, compared with those whose backup plans would be harder to execute.

"They perhaps did more poorly than they would have without a backup plan," Napolitano said. But it's important to stress that all of these findings are very dependent on the individual, the context and the goal, he added.

How tough your goal is, how predictable the outcome might be, how much time or money or strength you have to go after it and your own personality will all factor into whether your backup plan helps or harms you.

Building a better backup plan

So when is it actually helpful to have a backup plan? It might depend on the kind of auxiliary scheme you choose, Napolitano said.

One type, called contingent backup plan, is less likely to distract you. To make one, you decide ahead of time what conditions would get you to abandon plan A. You might set a contingent backup plan by deciding that if you haven't gotten any stronger by the end of the month, you'll up the number of your daily pushups.

"In these backup plans, people set really clear deadlines," Napolitano said. "You're not really thinking about the backup plan until you reach or near that deadline."

Other backup plans are fuzzier around the edges, and involve switching from plan A at some nebulous, undecided point. "You might get into more trouble when you make backup plans that we call redundant backup plans," Napolitano said. "You don't really have a clear marker about when to switch, you're always comparing."

A redundant backup plan might take the form, "I'll go see the professor whenever this class starts to feel too difficult," rather than, "If I score below a B on the next test, I'll ask my professor for help."

This doesn't mean you should never use redundant backup plans. When you're in situation where you have zero experience and aren't sure what will work, you might not be able to judge a good point to say that plan A is failing.

"If you don't have that marker, it's almost foolish to make contingent backup plans. You almost have to make these redundant backup plans," Napolitano said. "You have to start somewhere."

His advice: do research before you take the plunge to suss out what a reasonable deadline is for achieving your goal.

And sometimes, wing it.

"For some goals you may be better off going in…with no backup plan, and if you fail, well you learned new information and you can develop a new way based on that new information that you gathered," Napolitano said.

It all depends on what the stakes are. When you're going camping, you'll want to bring plenty of water. If you crack one water bottle, get lost or have to hike farther than you expected, that extra canteen could save you from dehydration or worse.

"Regardless of how crappy it is to carry all your water into the woods, it's a pretty good idea to have an extra bottle," Napolitano said. "So thinking about what the costs of true failure are is a nice way to measure whether a backup plan is useful or not."

Brain Candy
26 November 2015

As Thanksgiving approaches, Americans will be reflecting on things they're grateful for: family, health and good fortune of various sorts.

It might be wise, however, to give thanks for things not traditionally considered to be so positive: Strangers. Hard challenges. Even negative feelings.

Studies have found that bad stuff can be important to people's happiness and that, in fact, challenges can be immensely satisfying. In honor of the upcoming season of gratitude, here are a few rather counterintuitive things to be thankful for, and the research that backs them up.

1. Strangers and small talk

About to give thanks for your smartphone for keeping you entertained during your long train commute? Don't. Research suggests you'd be happier striking up a conversation with your seatmate.

It's a hard finding to believe — isn't small talk excruciating? Not according to a 2014 study by psychologists Juliana Schroeder and Nicholas Epley of the University of Chicago Booth School of Business. The team approached train commuters and asked some of them to spend their commute in silence and others to try to start a conversation with a stranger. Those assigned to start a conversation were more likely to expect an unpleasant commute. But the opposite happened: People who talked to a stranger during their train ride reported a more pleasant time.

The researchers followed up with a laboratory study in which people in waiting rooms were chatted up, and found that being on the receiving end of a conversational volley was pleasant, too. In other words, small talk with strangers is pleasant both for the person who initiates the conversation and for the person they choose to talk to.

"People estimated that less than 50 percent of people would be willing to talk to them if they tried," Epley said. "In fact, we never had a single person in our connection conditions who tried to talk to somebody and couldn't."

The fundamental misperception that strangers don't want to talk to you is probably why people stay silent, Epley said. But just because someone isn't talking to you doesn't mean they don't want to, he said. They're probably sitting there thinking you don't want to talk to them.

In some ways, Epley said, conversations with strangers may be uniquely edifying. He's stumbled across people with amazing stories by striking up conversations, he said, including a man who was one of the first to flee Cuba for Miami in a homemade boat.

"A stranger has this great benefit of being just a short little interaction," Epley said. "It doesn't have to go on for years. That means in those interactions you kind of cherry-pick the most interesting thing to talk about. You take a person who is distant and you shrink the world a little bit."

2. Holiday fundraisers

Around Thanksgiving and Christmas, grocery store aisles are festooned with appeals to donate a meal to the homeless. Toy drives collect presents for needy children. Salvation Army Santas ring bells outside of mall entrances.

It can feel a bit overwhelming. But don't turn away. Studies find that supporting those in need makes people happier than spending the same amount of money on themselves.

This essential generosity is surprisingly universal. A 2013 study published in the Journal of Personality and Social Psychology surveyed people in 136 nations around the world, rich and poor alike, and found that people who had donated to charity in the past month reported greater well-being than those who did not. The researchers estimated that the effect of having given to charity on well-being is approximately equal to doubling one's income.

In follow-up research in Canada and Uganda, people prompted to recall a time they'd spent money on themselves or on someone else. The people who recalled spending money on another person reported more happiness than the people thinking about buying something for themselves. It turns out that giving really is better than receiving.

3. New Year's resolutions

You know the drill: You promise to turn over a new leaf come January first, and you do … for a little while. What a waste of effort, right?

Nope. Just trying to do something hard might be a huge mood-booster. This is true, at least, of quitting smoking, a process that many smokers dread. A 2010 study, though, found that smokers showed a boost in mood as they tried to kick the cigarette habit, even if they were ultimately unsuccessful. Those who never tried to stop smoking during the 28-week study period were gloomiest of all, researchers reported in the journal Nicotine & Tobacco Research.

Indeed, setting ambitious goals is linked to improving happiness, even though such goals often involve greater risk than more conservative ones. A 2011 study on investing published in the Journal of Consumer Research asked people to set goals for the return on their stock portfolio. Logically, anyone meeting their goals should be satisfied. But the study found that those who aimed high were more satisfied at meeting their goals than those who aimed low and met their goals. People seem to set their standards against a high benchmark even if their own personal goal is low, and they're disappointed when their success doesn't reach that benchmark, the researchers wrote. (The good news is that reminding people that they'd picked low goals did help improve people's moods after they achieved those goals. So if you can't aim high, at least you can remind yourself that aiming low was your choice.)

4. Not getting everything on your Christmas list

If Santa doesn't bring everything on your list this year, say thanks anyway. A large body of research finds that material goods don't make people very happy at all.

We all need our basic requirements met, of course, but once people are reasonably well-off, more money does not seem to buy more happiness. In addition, materialism is consistently linked with lower well-being than other values, studies find. And getting new material goods is often a let-down.

"One thing that's really disappointing about material items is they often don't deliver," said Ryan Howell, a psychologist at the University of California, San Francisco, who studies consumerism and happiness. We think if we unwrap that new soufflé dish on Christmas morning, we'll become the sort of person who makes soufflés. We won't.

Likewise, people often underestimate the cost of having stuff, Howell said, from having to store it, to taking care of it, to replacing it when it's gone. People also tend to compare their things to other people's things, creating an unpleasant social competition not typically seen when people spend money on experiences, instead.

In short, a mountain of gifts to unwrap may leave you feeling a little empty. Without so much stuff, Howell said, "you lose some of the baggage that comes with these material items."

5. The holiday blues

The enforced cheer of the holiday season can feel a little bit oppressive for some. Research suggests you embrace that melancholy.

True well-being isn't about feeling nothing but happiness all the time. Instead, negative emotions are part of what makes people mentally healthy, as a 2012 study found. The researchers looked at 47 adults who were in psychotherapy. Each person wrote narratives about their thoughts, feelings and therapy experience. Many reported mixed feelings: Joy at a new pregnancy, for example, but simultaneous sadness over being unemployed. One woman described feeling sad and helpless, but happy that she was trying to improve her situation through therapy.

Unsurprisingly, as people reported more happy feelings and fewer sad feelings in these narratives over time, their well-being improved. But something more interesting emerged in the narratives featuring mixed happiness and sadness. Those writers got happier over time, too. Expressing mixed emotions at one time point was correlated with improved well-being later.

"The concurrent experience of happiness and sadness prospectively preceded increases in psychological well-being above and beyond the influence of happiness and sadness independently," the authors wrote. The benefit of mixed emotions on well-being isn't instantaneous, they went on, but unfolds over time. Trying to banish bad thoughts, in other words, is likely counterproductive.

"Treatment should not focus strictly on the elimination of negative emotional experience, as negative emotions may be fundamental in the process of clinical improvement," the researchers wrote.

Brain Candy
03 November 2015

What is sound, anyway?

Some of the most basic concepts of science are surprisingly hard to break down and explain. But if you've only got a vague idea of what sound really is (something to do with vibrations? Pressure is involved, right?), then you're in luck: scientists around the world have been challenged to come up with an explanation that satisfies grade school kids.

This yearly contest was launched in 2012 by actor Alan Alda, who heads the Alan Alda Center for Communicating Science at Stony Brook University in New York. The competition is a chance for scientists to figure out how to communicate scientific concepts that are both complex and experienced in people's everyday lives, like time, color or sleep.

The description must make sense to 11-year-olds, who will be judging the contest (teachers can sign their class or school up to participate here). Scientists have until 11:59pm on January 19, 2016 to submit their answers, which they must squeeze into 300 words or a video shorter than 5 minutes. The winners will be announced at the 2016 World Science Festival.

Alda founded the contest—called the Flame Challenge—to give kids and other curious people clearer answers to science-related queries than he got as a kid. "I wondered what a flame was when I was 11, and I asked a teacher to explain it to me," Alda told LiveScience. "All she said was, 'It's oxidation.' I never got a good explanation."

This year's question, "What is sound?" was chosen among hundreds brainstormed by kids from around the world. Some who asked about sound are curious about what makes sounds different from each other, while others want to know what makes up the sound of human voices.

"I can't wait to see how creatively scientists will explain exactly what sound is," Alda said in a statement. "The kids and I are all ears."

Brain Candy
29 October 2015

It's about midnight; my husband and I are returning to our bed and breakfast after a night out. A wall joins our room and the room next to ours with fake ivy-covered latticework at the top, too high to look through unless you've climbed a ladder. It's a little uncomfortable, but the other room is vacant for the night, so we settle in. Around 2 a.m., a noise startles me awake. It sounds like a rustling, someone shifting slightly bendable plastic back and forth. I look around for the source of the noise but don't see anything. Moonlight filters in through the window and onto the wall. And then I see it—a face, up at the latticework by the ceiling. It's a man, pulling aside the fake ivy, staring in from the other room, a huge grin on his face that's about to become hysterical laughter. His smile is twisted and angry and his eyes shimmer with anticipation. I try to scream, but all I can manage is a wheezy whisper. Not even close to waking up my husband. I try and try to scream but my vocal cords just never seem to catch a noise. My terror is real and palpable—until my husband shakes me awake, at home in our bed, out of the scene.

Luckily for my husband and I, that was just a dream. But the nightmare reflected something unique to me: When I'm truly scared, I can't make any noise at all. When others scream, I wheeze. When others pass out, I open my mouth and very quietly yell. My silence is just one reflexive action in a litany of responses to fear performed the world over—others include blushing, laughing, passing out, running, punching, crying, vomiting, and yes, urinating and defecating. So why does one person react to fear differently than another? Is the reaction itself a learned behavior or a neurological response?

Fear itself works as a chemical reaction in the brain and happens in two simultaneous ways through the limbic system—one quick and one long. With the quick way, your brain receives a scary stimulus and sends that information to the thalamus. The thalamus doesn't bother taking time to decide if the stimulus is a real danger or not; it immediately sends that information on to the amygdala, which then signals the hypothalamus to hit the fight-or-flight button. That's the you-got-scared-and-jumped part. At the same time, your brain is taking a longer path to determine if the stimulus is really a threat. The thalamus sends the initial input to the sensory cortex, which figures out the meaning behind the stimulus, and then passes the info to the hippocampus, which attempts to determine the context of the stimulus. Suppose that a face you thought you saw in the dark was just a creepy looking vase. The hippocampus would see that, and send the "no threat" signal to the amygdala, which tells the hypothalamus to cool it with the fight-or-flight.

Of course, during that time, you could have started violently puking out all your fear. Thanks, brain. Consider it as your thoughts catching up to your actions, just a little bit late.

As it turns out, that vomiting—or any of the other reactions people have to fear—are all part of the brain's subconscious risk assessment as it processes the scary stimuli. Instinctually, your brain will determine the most important thing it can do to help you release tension and cope with that fear, and then spark an action.

Vomiters, your brain is telling your body that it needs to feel better—and like with food poisoning or the flu, throwing up brings that relief. Laughter is a "don't look at me" response, telling others around you that there's no problem so they don't come over and join the thing making you afraid. Someone who cries when they're scared is releasing stress-causing hormones in those tears so they can calm down easier.

People who faint, I'm sorry to say that your brain is just trying too hard. This response is called vasovagal syncope. Your brain simultaneously activates and inhibits two branches of your autonomic nervous system, leading to a drop in blood pressure and heart rate, and the resulting dip in the blood supply to the brain causes fainting.

As for people who freeze like I do, it's actually a form of playing dead, a response to show whatever scared me that I'm not a threat because, whoops, I'm already dead. So it can leave me alone.

But why, then, does a fear of something like spiders remain a quick fright while someone else's might spiral into a full-blown anxiety disorder or phobia? According to NYU neuroscientist Joseph LeDoux, a biological and external mixture is at play. We are each born with our own unique sets of genes, and we each go through different experiences in our lives, and those things combined may create a phobic disorder. For example, I may just think spiders are gross—but maybe Johnny over there lived in a spider-infested apartment and woke up with spider bites, and his family history shows a recurrence of anxiety disorders. Johnny is more likely to develop that deeper terror because he's predisposed to it.

In this way, we're actually pretty closely related to animals, which experience fear in an incredibly similar way. It's a phenomenon called associative learning. We subconsciously correlate a fearful experience with some sort of visual cue, and then every time we see that visual cue, it triggers fear. So really, even though we have these big powerful brains, they sometimes can't do much about our subconscious fear processing. Like I said before, thanks a lot, brain.

Brain Candy
29 October 2015

The grand cake artist Yolanda Gampp has quite a number of mindblowing sweet inventions on her YouTube show " How To Cake It." One of her very best is a brain-shaped red velvet cake that she made for the premiere of The Walking Dead earlier this month. So naturally, we had to watch, learn, and make it ourselves for Halloween.

All you need is a cake, fondant rolled into tubes and raspberry jam for a bloody effect, as well as good anatomical knowledge or a picture from the internet. The cake can be a red velvet (get Yolanda's recipe from here), or even a pumpkin cake made out of the by-products of your pumpkin-carving adventures.

Here's our cake. Slightly deformed, perhaps too wrinkly compared to a real brain but at least this one doesn't have to think:


And here's the master's:


Enjoy, zombies.

Brain Candy
28 October 2015

There's a now new way for experiencing your own writing. Typatone, an app made by Jono Brandel and Lullatone, is a digital typewriter that plays a sound for each letter you type. When you read back your text, words and sentences become a musical composition.

The inspiration for the app comes from synesthesia, a phenomenon in which senses can bind together and one sensory experience triggers perception in a different sense. For example, some people may see letters of the alphabet in different colors and others may assign shapes to certain tastes. Synesthesia is not very common, but apps like Typatone might help show what it's like. Try it out:

Once you have something written you can download your writing as a WAV file or share it with friend. Over one week since the launch of the app, more than 10,000 messages have been sent, Brandel says. Some people are writing simple messages to friends like "Happy Birthday," while others are typing out their own musical haiku. Typatone has 6 different filters that changes the mood and quality of the sound. There's an app (android and iOS) and a free website.

Last year the team launched an app called Patatap that turned keyboard strokes to combinations of sounds and colorful shapes. The new app is more focused on writing, hoping to help writers understand their writing in a new way through sound, Brandel says. "You can easily hear and discern patterns in your writing. I use certain words a lot and I hear them, which helps the editing process. It's a new way of receiving information that you put down on the page."

And for everybody else, too, sound could add a new dimension to text messages and make our interactions a more immersive experience. Perhaps one day we'd be able to tell a short text message like "OK" or "LOL" by just the sound of it.

Brain Candy
16 October 2015

The search for the elusive funny bone has ended; it's located in the brain…and it isn't a bone.

Humor sometimes relies on culture and social mores to generate a laugh, but the foundation for everything funny is the same for all people—it's grounded in an expanded network of brain areas, each working to process one aspect of this multifaceted cognitive experience we call a joke.

How does the brain get it? It all starts when visual signals from a cartoon or auditory signals from a pun hit the brain. But the heart of what's funny in a joke is the mismatch between what we expect to see and what we get, something researchers call incongruity. Once certain brain areas process and flag this mismatch, a flurry of happy emotions and boats of laughter ensue, according to research studies with decidedly un-funny language.

Tracing a joke in the brain

The field of studying humor in the brain is relatively new, says Dr. Anjan Chatterjee, a professor and neurologist at the University of Pennsylvania. But over the past two decades studies have used brain imaging technologies to peek into the brain at the moment of a joke.

To understand what parts of the brain areas are involved in processing humor, scientists have to break down the components of humor, mainly the cognitive elements and the emotional response.

The cognitive aspects of humor require the brain to recognize the incongruity employed to make the funny point. It's necessary to identify and comprehend two juxtaposed ideas to get a joke. The short storyline of a joke works to undo the simple assumptions we automatically make at the start.

For example: "I went to buy some camouflage trousers the other day but I couldn't find any."

The joke works if you first think of camouflage as just the color description, and only at the end think of the function of camouflage apparel, which is, to hide from view.

To process this juxtaposition, studies have found that people employ multiple brain regions from parts of the prefrontal cortex to areas in the temporal lobe, as well as the anterior cingulate cortex, which is known for its role in error detection. After reviewing the findings of these studies, neuroscientist Jessica Black of Boston College and her colleagues suggested these mechanisms point to a core processing area, which includes the temporo-parietal junction.

Once the incongruity of a joke is resolved, it leads to amusement, an emotional reaction that activates the reward centers of the brain. The release of dopamine to help the brain process emotions enhances the experience of pleasure and increases serotonin levels that elevate mood.

This amusement is tightly linked to resolving the incongruity of the joke. As the saying goes, if you explain a joke, it's no longer funny.

"Those surprise element, where you internally have to have an 'ah-hah' moment where it all comes together, is a critical feature to then having that pleasure response," Chatterjee says.

This vast network for humor processing is as susceptible to malfunction as the rest of the brain, and sometime brain problems can render a person immune to jokes. Damage to brain tissue can make it impossible to detect two incongruent ideas, taking all the fun out of a punch line. And mental health issues, such as depression, can dampen the amusement generated by resolving the joke.

Comedy-loving human societies

The subjectivity of humor – what's funny to one person or culture isn't funny and might even be offensive to another person or culture – is more difficult to address. "Things that are social that are consistently social have an effect on the brain," Chatterjee says. But without an historical record of data over time, identifying what has evolved into elements of humor isn't as easy as identifying more primitive traits such as "fight or flight."

But whatever the reasons are, humor has a prominent role in all societies. Among the theories trying to explain this is the "superiority theory," which suggests that humor is a non-threatening way to present dissenting views or negative feelings in an acceptable way as a means to preserve the social structure and reinforce the social bonds instead of threaten them.

Another theory, "Tension-relief," identifies humor as a stress reducer that provides psychological relief from tension for individuals, as well as the group. The feel-good benefits produced by the endocrine system coupled, with the relief of muscle tension, can shift focus away from stressful behaviors such as constant vigilance. And another theory holds that humor plays a role in sexual selection as an indicator of a qualified mate.

As theories go, these make sense to Chatterjee.

"People feel good laughing together," he says. "It might predispose these small groups of people to be a more cohesive unit and consequently be more likely to survive under harsh conditions. As a behavioral mechanism, it might have had consequences on just the probability of a group of people surviving. Over multiple generations, that becomes more engrained."

Odd Brains
16 October 2015

Imagine placing a raisin in your hand. You examine it closely, visualizing it in grape-form, growing plump on the vine. You take in the color, texture and scent as you resist the urge to pop it in your mouth. At last, you nibble the raisin, pausing to consider its flavor before chewing and swallowing.

Meditative exercises like this one might make you more aware of things happening around you, a new experiment shows—even things that you'd normally miss, thanks to a phenomenon called inattentional blindness.

Inattentional blindness, which reflects our miserably limited attentional resources, is best shown in a classic experiment in which half of the people watching a simple ball passing video failed to notice a person in a gorilla suit walking across the stage. That and many other similar experiments that followed have shown that no matter how hard we try to absorb everything around us, there's always something we miss, and sometimes that thing can be as dangerous as a fast approaching car. So, raisins could potentially save your life.

In the study, published in the journal Consciousness and Cognition, researchers gave 800 people either a 7-minute mindfulness exercise with raisins or a non-meditative recording of general facts about raisins. Then the participants were faced with a computer screen and had to count the number of times black and white letters bounced off the edge.

Focusing on such a task requires enough mental resources to turn people blind to everything else. Just like in the gorilla experiment, half of the people would fail to see anything else popping up on the screen.

But it turned out that those participants who had done the raisin meditation were more likely than the rest to notice an unexpected red cross hovering among the numbers. This finding is in line with the idea that mindfulness encourages people to monitor their environment more thoroughly, but it has to be replicated in future studies, the researchers said.

It's also unclear how mindfulness may be lowering inattentional blindness, the researchers said. Mindfulness is a mental state in which people let themselves become aware of whatever feelings, observations and experiences they have in the moment, accepting them without judgment. Perhaps, during a rigid task of focused counting, mindfulness prevents the rules of the task from being the sole guides of attention, giving a better chance for other events like the hovering red cross symbol to win some attentional resources.

Brain Candy
13 October 2015

Are you curious about the brain? Are you excited to learn about the small but magnificent organic machine you carry for life on your shoulders?

If so, there's plenty of resources out there. Plenty of resources that will go straight over your head.

Luckily, there's also this "brain map" that takes you on a treasure hunt around a brain-shaped island, explaining the various brain regions that, all together, make you tick. Drawn by psychologist Richard Roche of Maynooth University, the map contains several references to iconic events, people and facts related to neuroscience:


1. Santiago Ramon y Cajal

The map legend features two key figures in the history of neuroscience. First, on the left, is Spanish neuroscientist Santiago Ramon y Cajal with his microscope on the mantelpiece. Cajal, designated by many as the father of modern neuroscience, was a brilliant scientist who improved methods of studying the brain's microscopic structure and discovered the anatomical properties of neurons. His work kickstarted a new era in brain sciences.

2. Phineas Gage

The man sitting next to Cajal is Phineas Gage, the most famous patient in the history of neuroscience. Gage was a young railroad worker in 1848 when an explosion shot a tamping iron towards his head. The 43-inch-long bar penetrated Gage's left cheek, destroyed frontal parts of his brain, and exited from the other side of his skull. But it didn't kill him. Gage lived for another 12 years and showed profound changes in his personality, according to his, at least for some time after the injury. However, some evidence suggests Gage actually became normal a while later. Whatever was his true fate, he became the first patient from whom we learned something about the link between personality and the function of the brain's frontal lobe.


3. The clock test

The mantelpiece also features a clock with only one side bearing numerals. This is in reference to spatial neglect syndrome, in which patients are unaware of one side of the space. Neglect syndrome can occur after a stroke damages part of the brain's parietal lobe. If the damage is in the right parietal, patients with neglect would become unaware of objects in the left side of their visual field. These patients may eat the food only on one side of their plate and shave half of their face. The clock test is a simple way to examine whether a patient has spatial neglect. When the patient is asked to draw the face of a clock, the drawing might show only half of the numbers or all 12 numbers on one half of the clock face.

4. Patient H.M.

Next to the clock, there's a model airplane, which refers to a childhood memory of the famous amnesic patient, Henry Molaison, or Patient H.M., who became unable to form new memories after parts of his brain were removed in an attempt to treat his epilepsy. The case of Patient H.M. was thoroughly studied for decades and taught neuroscientists a lot about the relationship between memory formation and part of the brain called the hippocampus. H.M. could still recall general facts about his past but couldn't remember episodic memories, which are memories of events at a particular time and place. The only childhood memory he remembered was of one of his birthdays, in which he went on a small plane and flew around Hartford.


5. The hippocampus

The sea monster on the top left corner of the map bears the head of a seahorse in reference to the hippocampus, the brain structure crucial for spatial navigation and processing and forming memories. The distinct curved shape of this structure has been likened to several forms, from a silkworm, suggested by Venetian anatomist Julius Caesar Aranzi in the late 16th century, to a ram's horn, proposed by Danish anatomist Jacob Winsløw in the 18th century. But the one that stuck was that of a seahorse and therefore this structure is called hippocampus, a name derived from the Greek words hippos, for "horse" and kampos, for "sea monster."


6. The earliest recorded reference to the brain

At the foot of the mantelpiece are the hieroglyphics which constitute the first written reference to brain injury in the human record, taken from a papyrus written in the 17th century B.C. The word brain appears eight times in the papyrus, which describes the symptoms and treatment of two patients with fractured skulls.

7. The building blocks of the brain

Look closely at the map and you'll see the border is composed of 108 neurons, joined together by their dendrites and axons, the tentacle-like branches coming out of a neuron's body. The human brain is estimated to have about 85 billion neurons, with each neuron connecting to 1,000 to 10,000 others to exchange information in places called synapses.

Neurons have many types with varying physiology and firing patterns. But neurons are not the only brain cells. Another major type of cells in the brain are the glial cells, or the glia. These cells are crucial for support and protection of neurons and their malfunction is linked to some neurological diseases. One type of glial cells are star-shaped cells called astrocytes, found throughout the brain and spinal cord, and featured here in the map's compass.

8. Trepanned skulls

The two top corners feature trepanned skulls, references to the ancient practice of trepanning in which crude holes were drilled into the skull to release evil spirits or cure maladies.


9. The brainstem and the cerebellum

The two smaller islands represent the brainstem and the cerebellum. The brainstem island is host to tornadoes, as a reference to the role of this structure in regulating breathing and respiration. The cerebellum, sitting right behind the brainstem at the top of the spinal cord, is a dense structure packing as many neurons as the rest of the brain. The most well known roles of this structure is to maintain balance and fine-tune motor movements. To represent this the coastline of the cerebellar island is battered by turbulent waves.


10. The occipital lobe

The occipital lobe, one of the four lobes of the brain, sits at the back of the head and is the center for visual processing. The lighthouse at the edge of the island represents the area V1 or Primary Visual Cortex, the first area to receive visual signals from the eyes. A viaduct is put in the region of visual color area V4 to represent the way in which different senses can display unusual connectivity in conditions such as synesthesia. A water mill on a flowing river is shown in the region of area V5 representing visual motion processing in this region.


11. The temporal lobe

The temporal lobes are located on the sides of the head, behind the ears. Two rivers running in parallel represent the two major folds called temporal sulci, while a small wood is located at Wernicke's Area—the language comprehension center of the brain. A warehouse represents the role of the temporal cortex in long-term memory storage. Lower down, there's an area called the Fusiform Face Area, which is involved in processing faces. The same area also lights up when people see faces in noisy patterns, in a phenomenon called pareidolia. A rock formation similar to the infamous Face on Mars represents this phenomenon.


12. The parietal lobe
A lot of what happens in this lobe has to do with integrating senses coming from other parts of the brain. The busy "Port Rietal" represents the way in which this lobe's areas 5 and 7 receive signals from multiple senses and contribute to our sense of location in space. The human-shaped lake "Lough Homuncu" resembles the idea of the "cortical homunculus," a neurological map of body parts. The 6-story tower represents a "cortical column," a patch of neurons stacked in the layered structure of the cortex.


13. The frontal lobe
The frontal lobe is involved in many important cognitive skills in humans, such as planning, problem solving and decision making. A city representing civilization and society is located in the prefrontal region, and is named 'Korbinian' after Korbinian Brodmann who produced a map of cortical regions still used today. One of the rail lines from Korbinian terminates at Gage Rock, another reference to the accident Phineas Gage endured. The other line connects Korbinian to the town of 'Leborgne', named after a famous patient examined by the French physician Paul Broca around 1860. Leborgne had progressively lost his ability to speak and was nicknamed Tan—the only word he could say clearly. After Leborgne died, Broca performed an autopsy and discovered damage in an area of the brain that later became known as the speech production center of the brain, now called Broca's area.

Brain Candy
08 October 2015

"I love deadlines," English author Douglas Adams once wrote. "I love the whooshing noise they make as they go by."

We've all had the experience of wanting to get a project done but putting it off for later. Sometimes we wait because we just don't care enough about the project, but other times we care a lot – and still end up doing something else. I, for one, end up cleaning my house when I have a lot of papers to grade, even though I know I need to grade them.

So why do we procrastinate? Are we built to operate this way at some times? Or is there something wrong with the way we're approaching work?

These questions are central to my research on goal pursuit, which could offer some clues from neuroscience about why we procrastinate – and how to overcome this tendency.

To do, or not to do

It all starts with a simple choice between working now on a given project and doing anything else: working on a different project, doing something fun or doing nothing at all.

The decision to work on something is driven by how much we value accomplishing the project in that moment – what psychologists call its subjective value. And procrastination, in psychological terms, is what happens when the value of doing something else outweighs the value of working now.

This way of thinking suggests a simple trick to defeat procrastination: find a way to boost the subjective value of working now, relative to the value of other things. You could increase the value of the project, decrease the value of the distraction, or some combination of the two.

For example, instead of cleaning my house, I might try to focus on why grading is personally important to me. Or I could think about how unpleasant cleaning can actually be – especially when sharing a house with a toddler.

It's simple advice, but adhering to this strategy can be quite difficult, mainly because there are so many forces that diminish the value of working in the present.


The distant deadline

People are not entirely rational in the way they value things. For example, a dollar bill is worth exactly the same today as it is a week from now, but its subjective value – roughly how good it would feel to own a dollar – depends on other factors besides its face value, such as when we receive it.

The tendency for people to devalue money and other goods based on time is called delay discounting. For example, one study showed that, on average, receiving $100 three months from now is worth the same to people as receiving $83 right now. People would rather lose $17 than wait a few months to get a larger reward.

Other factors also influence subjective value, such as how much money someone has recently gained or lost. The key point is that there is not a perfect match between objective value and subjective value.

Delay discounting is a factor in procrastination because the completion of the project happens in the future. Getting something done is a delayed reward, so its value in the present is reduced: the further away the deadline is, the less attractive it seems to work on the project right now.

Studies have repeatedly shown that the tendency to procrastinate closely follows economic models of delay discounting. Furthermore, people who characterize themselves as procrastinators show an exaggerated effect. They discount the value of getting something done ahead of time even more than other people.

One way to increase the value of completing a task is to make the finish line seem closer. For example, vividly imagining a future reward reduces delay discounting.

No work is 'effortless'

Not only can completing a project be devalued because it happens in the future, but working on a project can also be unattractive due to the simple fact that work takes effort.

New research supports the idea that mental effort is intrinsically costly; for this reason, people generally choose to work on an easier task rather than a harder task. Furthermore, there are greater subjective costs for work that feels harder (though these costs can be offset by experience with the task at hand).

This leads to the interesting prediction that people would procrastinate more the harder they expect the work to be. That's because the more effort a task requires, the more someone stands to gain by putting the same amount of effort into something else (a phenomenon economists call opportunity costs). Opportunity costs make working on something that seems hard feels like a loss.

Sure enough, a group of studies shows that people procrastinate more on unpleasant tasks. These results suggest that reducing the pain of working on a project, for example by breaking it down into more familiar and manageable pieces, would be an effective way to reduce procrastination.

Your work, your identity

When we write that procrastination is a side effect of the way we value things, it frames task completion as a product of motivation, rather than ability.

In other words, you can be really good at something, whether it's cooking a gourmet meal or writing a story, but if you don't possess the motivation, or sense of importance, to complete the task, it'll likely be put off.

It was for this reason that the writer Robert Hanks, in a recent essay for the London Review of Books, described procrastination as "a failure of appetites."

The source of this "appetite" can be a bit tricky. But one could argue that, like our (real) appetite for food, it's something that's closely intertwined with our daily lives, our culture and our sense of who we are.

So how does one increase the subjective value of a project? A powerful way – one that my graduate students and I have written about in detail – is to connect the project to your self-concept. Our hypothesis is that projects seen as important to a person's self-concept will hold more subjective value for that person.

It's for this reason that Hanks also wrote that procrastination seems to stem from a failure to "identify sufficiently with your future self" – in other words, the self for whom the goal is most relevant.

Because people are motivated to maintain a positive self-concept, goals connected closely to one's sense of self or identity take on much more value.

Connecting the project to more immediate sources of value, such as life goals or core values, can fill the deficit in subjective value that underlies procrastination.

This article first appeared on The Conversation and is republished here under a Creative Commons license.

Brain Candy
08 October 2015

Politicians: Your faces matter. After the second Republican debate in September, Donald Trump's visage dominated both social and traditional media. CNN put up a huge banner of his more extreme facial expressions. Other politicians have experienced this sort of expression scrutiny, too, getting judged by the faces they make. House Speaker John Boehner, for example, has a reputation for getting teary-eyed. After Pope Francis visited Washington, D.C., GIFs of Boehner's attempts to control his emotions went viral. "The pope brought out John Boehner's best cry face," Mashable declared.

But a facial expression doesn't have to be over-the-top to communicate a great deal, as an analysis of 2012 Republican primary candidates reveals.

The smallest muscle movements can differentiate between a smile voters find appealing and those they find off-putting, according to an article in the spring issue of the journal Politics and the Life Sciences. Voters can tell a posed smile from one that communicates true enjoyment — and, unsurprisingly, they prefer the latter.

Studying politicians' expressions goes back to at least the 1980s. Back then, facial expressions were categorized as happy/reassuring, angry/threatening or fearful/evasive, for the most part. But tiny details in these expressions have become ever-more important in a world of high-definition video and looping online GIFs. And the new study examines some of the intricacies of the "happy" face by looking at individual types of smiles.

Using the at-the-time ongoing Republican primary as a test case, University of Arkansas psychologist Patrick Stewart and his colleagues gathered video from the 2012 Conservative Political Action Conference (CPAC), where candidates had gathered to woo primary voters. They chose short video clips of each candidate smiling and analyzed them frame-by-frame to determine the anatomy of each grin. They then asked 91 participants to identify the emotions in each smile in order to determine the different smile types on display. We've broken down the smile types below; get a mirror and play along for the full effect. (Or you can watch the video clips Stewart provided.)

Type of Smile Description
Posed Lip corners pulled up and at an angle.
Enjoyment ("true smile") Lip corners up and muscles around the eyes contracted.
Amusement Lip corners up, eye muscles contracted and jaw dropped to reveal teeth.
Controlled Lip corners up, eyes contracted, jaw dropped and lip corners tightened and pulled downwards to stifle the smile somewhat.
Contempt Lip corner on only one side pulled up at an angle and tightened.

The results revealed that there were very few "true" enjoyment smiles happening at CPAC. In fact, Stewart and his team identified only one, by then-Texas governor Rick Perry. This doesn't mean the candidates weren't having fun, Stewart said — instead, they conveyed their happiness with open-mouthed amusement smiles, which were displayed by candidates Michelle Bachman, Jon Huntsman, Tim Pawlenty (twice!), Herman Cain and Newt Gingrich.

Mitt Romney, Michelle Bachmann, Rick Perry, Gary Johnson, Ron Paul and Rick Santorum all displayed controlled smiles, mostly in response to audience applause — it's likely that they wished to show pleasure but not look too smug in response to praise, the researchers wrote. Herman Cain and Mitt Romney each showed contempt smiles.

Of all of the varieties on display, participants rated posed smiles as the least happy. They singled out Newt Gingrich's posed smiles are particularly unconvincing, but believed that Jon Huntsman's were the most genuine. The amusement smiles and Rick Perry's enjoyment smile were viewed most positively, while controlled smiles were seen as less happy and more negative.

Finding contempt smiles at all was a surprise, Stewart said, because it's an odd "two-faced," sort of expression: Half disdain, half affection, usually reserved for a member of our own group who has disgusted us.


Unfortunately for candidates, attempting to control one's facial expressions usually ends with strange and stilted looks, Stewart said. But voters, on the other hand, can take home a useful message from the research.

"We have evolved to make important decisions based upon paying attention to other people's nonverbal behavior," he said. "And when we have to rely on leaders who will deal with unpredictable situations, understanding their personality through their nonverbal behavior might be a more accurate approach than choosing based upon policy positions or political party identification."

Brain Candy
05 October 2015

What would you do if you were marooned on Mars like the fictional astronaut Mark Watney in The Martian? All alone, with little chance of ever getting out of there alive, would you start to panic? Would you eat all your food and overdose on painkillers as an easy way out? After all, you are presumed dead by all members of your species. Or would you choose to see the little drops left in the empty glass and enjoy the gorgeous Martian scenery?

And if you did go for the brave, optimistic attitude, opting to science your way of an uninhabitable planet, what would those months of pure solitude in an austere environment do to your brain and mind?

Watney's brain and body is outside the Earth's protective magnetic field and therefore exposed to cosmic rays. Scientists don't know the extent and type of damage that this radiation could cause in long term but recently a study in mice pointed to disfigured neurons and cognitive deficits. What would happen to Watney psychologically is better studied. Isolation can take many different forms, from solitary confinement in prisons to long space flights, but the effects of solitude on the highly social mind of humans are indisputable. For example, studies on prisoners have linked isolation with anxiety, panic attacks, depression, and anger. Studies in rodents have found isolation can harm basic social skills and memory. And reports going back to early 1800s have found high rates of mental illness and susceptibility to hallucinations and distorted sensations among confined people.

But Watney is shielded from many of these threats thanks to his personality traits. As Vanessa Hill explains in a new episode of BrainCraft (a web series from PBS Digital Studios), Watney exhibits exactly the key personality traits that are looked for in astronauts. For example, he is resilient in the face of many setbacks to his survival plan. Or, he keeps his sense of humor, managing to make up a joke no matter how dire the situation is. Watch the video to learn more about these and other personality traits that can come in handy for the rest of us on Earth as well:


Brain Candy
28 September 2015

One night when I was five or six, I recall becoming frustrated by how much attention my mother was spending on reading books to my little brother. "He's just jealous!" I finally burst out.

It must have been pretty obvious to my parents that my brother was not the one who was jealous. My declaration was a very common kind of defense mechanism, one of the numerous unconscious techniques that people use to cope with upsetting or painful ideas.

Defense mechanisms can vary based on how primitive they are. As psychologist John M. Grohol recently pointed out on PsychCentral, the more primitive a defense mechanism, the less effectively it works for a person. However, more primitive defense mechanisms are usually very effective short-term, and that's why they are commonly used by many people, especially children.

People often aren't aware that they are relying on defense mechanisms to protect themselves. While many defense mechanisms aren't actually very helpful, a few can be constructive. Here are some common primitive strategies and their more effective counterparts:


This is the defense mechanism I fell back on, in which a person assigns their own unwanted feelings to someone else. This lets people view the threatening idea as coming from the outside world instead of themselves.



Probably the most famous defense mechanism is denial, the refusal to accept unpleasant truths. People who are in denial simply ignore reality, whether they are refusing to accept the death of a loved one or responsibility for their own actions.

Acting out

When people act out, they express wishes or impulses in the form of an action, without really understanding the emotion that's driving their behavior. Children do this when they throw a tantrum because they can't pinpoint or explain that they are annoyed or tired.


Instead of resolving a conflict some people may choose to sink into fantasy. While daydreaming can help people relax, fantasizing becomes a problem when people just imagine their problems being solved instead of doing something about them—like when a stressed student imagines how nice it would be to earn an A on an exam instead of actually studying.


Recreation formation

Instead of trying to push unwanted feelings onto other people, this defense mechanism tries to turn them into their opposites. Someone practicing recreation formation might try to be extra nice to someone they can't stand, shoving down their real feelings while around them.


This happens when people cannot or don't feel safe venting their spleen at whom or whatever they are actually mad at. People displace their anger by taking it out on another target, as in the scene in It's a Wonderful Life when George Bailey snaps at his family and yells at his daughter's teacher after his uncle misplaces money needed for the family business.



Undoing is an attempt to take back or atone for thoughtless but hurtful words or actions. By being courteous and directing nice gestures or praise at someone they have wronged, people who engage in undoing try to cut down on the damage and guilt they've stirred up.

Wishful thinking

When faced with harsh reality some people may instead imagine a more pleasing situation and base their decisions on what they like to see happen rather than what is likely to happen. Someone indulging in wishful thinking might hit the "next episode" button again when it's already bedtime, telling themselves, "I'll just watch for a few minutes."


More mature ways of dealing with problems that can be constructive and helpful:


People sublimate unwanted feelings by diverting the energy spent on them into more productive activities, like exercise or a joke. Sublimation is considered a mature defense mechanism, and can help being make peace with their anxieties without sabotaging themselves or those around them.


In this strategy, people try to offset or balance weakness in one field by emphasizing strength in another. A small dose of compensation can be healthy, such as a woman who has done terribly on her first swimming lesson reminding herself that she is a very good driver.


Assertiveness is a communication style that is respectful but firm and straightforward. Someone who has mastered this technique can be a good listener without being a doormat, and communicate their own ideas, opinions or needs without steamrolling other people.

Brain Candy
14 September 2015

Animals can be fooled by many of the same illusions that hoodwink humans. But in at least a few cases, they create subtle illusions of their own to manipulate how other animals view them. Studying how animals sway other creatures' sensory experience might offer scientists a few clues about how different senses and the signals animals use to communicate evolved—and how much their world is like ours.

Here are six ways animals put themselves in the best light, whether that means seeming more intimidating to predators or attractive to potential mates.

1. Using their own bodies to make themselves look bigger

Whether animals are looking for love or trying to scare off predators, bigger is often better. Most cat owners are familiar with how upset animals try to puff themselves up to look larger than they are.


But some animals take these displays a step farther, creating an actual illusion.

Male peacock spiders benefit from looking bigger than they are when they're cruising for a mate. During courtship, these spiders raise their technicolor abdominal flap, along with their third pair of legs.


"Raising the legs alongside the abdominal flaps is likely to make the flaps (and therefore the male) appear taller and wider than they are in reality," wrote the authors of a review of research on animal illusions. This is "similar to the Müller-Lyer illusion that many nonhuman animals are susceptible to."


In the Müller-Lyer illusion, above, the horizontal lines are the same length. For each set of line and brackets, viewers estimate how long the central line is from an overall impression that includes the lines it is sandwiched between. The top line seems longer, but it isn't.

2. Using rivals' bodies to make themselves look bigger

Other animals can create an illusion based on the context of their surroundings. When male banana fiddler crabs are hot to trot, they gather in dense communities that females then browse.


Females like a guy with large claws, and are more likely to sidle up to a male when he is alongside smaller-clawed rivals. This could be because a crab surrounded by more petite neighbors creates the Ebbinghaus (or Ebbinghaus-Titchener) illusion. In this illusion, an object looks larger than it really is when surrounded by smaller satellites (and smaller than it actually is when surrounded by larger objects).


However, the crabs may not be using the visual illusion intentionally. "There is currently only indirect evidence that male fiddler crabs actively manipulate their social environment in order to increase their relative attractiveness," wrote the authors.

Guppies offer more direct evidence that males use the Ebbinghaus illusion, they said. Here, females are drawn to very colorful males. Male guppies actively seek out rivals with smaller color spots to strut their stuff next to.



3. Making their plunder look more impressive

Another, more elaborate trick is played by male great bowerbirds. To attract the ladies, males build a tunnel-shaped bower. This opens onto a little court filled with stones, shells and bones, garnished with a few colorful decorations. The larger the stones and other detritus are, the farther the male places them from the entrance to the bower. This creates an illusion called forced perspective, researchers suggested in a 2012 paper. Females view the court from within the bower. Forced perspective makes the court appear smaller or less deep than it really is, and displayed ornaments appear larger.


Kelley and Endler

4. Hiding their real shape

Camouflage needn't just make an animal the same color as its surroundings—it can also distort the animal's body. Patchy markings can break up its outline and create the illusion of a group of unrelated objects. The spotted marsh frog uses high-contrast lines to border its color patches. "These 'false edges' are highly indistinguishable from the 'natural edges' formed by the prey's body, preventing visual recognition of the animal as distinct from the background," wrote the review authors.


Matt Clancy via Wikimedia Commons, CC BY 2.0

5. Making themselves appear more vibrant and colorful

We judge the brightness of an object based on what's going on in the background. If a gray bar is surrounded by lighter gray, the bar appears darker than when it has a deeper gray background. This is called simultaneous brightness contrast, and shows that, as in the Ebbinghaus illusion, what we see can be warped by context.

"Many animals use color in their sexual displays and could manipulate the perception of brightness or color of bodily patches or other stimuli via the surrounding region," wrote the authors of the review. "Courting males could make their coloration appear brighter if they display against a low luminance background."


Simultaneous brightness contrast. The bar of gray is all one color, and the numbered tiles are the same shade of orange. Image: Kelly and Kelly.

In fact, this appears to be what a few amorous birds do to put their best wing forward. In some species, males gather on a patch of ground called a lek and mill about, staking out small territories from which to woo females. But what makes them choose a particular site for lekking?

One study found that tropical birds called manakins seek out lighting that best increases the contrast of their own colors against the background, or within their own patterns. Another study observed that species have preferences for what environment they situate their lek in. "The color patterns and behavior of each species maximize its visual contrast during its display and reduce it off the lek," researchers concluded. "Each species does this with a different combination of colors and light environments."

6. Using their colors to confuse enemies

Not all camouflage helps an animal fade into the background. The vivid black and white stripes zebras wear make them hard to miss against the surrounding vegetation. But those stripes are still a sort of dazzle camouflage.

When striped patterns are set in motion, they can create several different optical illusions, including the wagon-wheel effect (in which the spokes on a wheel appear to spin backwards) and the barberpole illusion (on barber poles, the stripes seem to travel upwards even though the pole is actually rotating in place).


Animated Example of the Barberpole Illusion. Created by Bas Rokers, CC BY-SA 3.0

Zebras replicate these illusions when they move, researchers proposed in one study.

"The motion signals that these coat patterns generate could be a highly misleading source of information," they wrote. "We suggest that the observer's visual system is flooded with erroneous motion signals that correspond to [these] two well-known visual illusions."

Dazzle camouflage can stymie predators about how fast or in what direction an animal is moving. In the case of the zebras, "The vertical stripes in the flank region can generate motion signals in the opposite direction to actual movement – similar to the wagon wheel effect," wrote the researchers. "The diagonal stripes of the rump region of the animal produce motion signals 50–60 degrees away from the actual movement direction – similar to the barber pole illusion."

The two illusions probably act together to confuse biting insects that approach from the air or predators on the hunt, they concluded.