Field of Science

Even People Without Synesthesia Find Colors in Music


It’s time to stop scoffing at the synesthetes: linking music to colors is totally normal. It’s not really about the notes, though. Researchers say the colors we find in music are actually the colors of the emotions the music makes us feel.

Synesthetes are people whose sensory experiences overlap; they most often link letters or numbers to certain colors. Music-color synesthesia, in which hearing music triggers the colors, is rarer. In fact, when Stephen Palmer and Karen Schloss at the University of California, Berkeley, set out to do a pilot study of music-color synesthetes, they couldn’t find any. So instead they began looking at the connections between music and colors in everybody else.

As part of a larger study called the Berkeley Color Project, Palmer and Schloss included questions about music. Participants saw a grid of colors while listening to 18 brief clips of classical pieces, and chose the colors that were “most consistent” and "least consistent" with each selection.

The researchers suspected that a connection between music and color, if there was one, might be emotional. So they separately asked their 48 subjects how happy, sad, angry, calm, strong, weak, lively and dreary each piece of music was. Subjects answered the same emotional questions about each color. (If you’re the kind of person who hates attributing personality traits to color swatches, you would not have enjoyed this study.)

There were 18 music samples, representing every possible combination of 3 composers (Bach, Mozart, Brahms), 3 tempi (fast, medium, slow), and 2 modes (major or minor). The Andante movement of Bach's Brandenburg concerto in F major, for example, was Bach/major/slow.

What emerged from this sea of lively Mozart and sad burnt-orange was a clear pattern. People linked uptempo and major-key music to colors that were warmer (yellower), lighter, and more vivid. Pieces with a slower tempo or in a minor key provoked the opposite colors: cooler (bluer), darker, and less saturated.

Additionally, music that was both slow and in a major key tended to be greener. And although there wasn’t a difference between Mozart and Bach, Brahms—a Romantic composer who wrote the most recently of the three—leaned more to the slow and minor colors.

To learn whether this consistency was strictly cultural, Palmer and Schloss found a collaborator at the University of Guadalajara who wanted to repeat the experiments with Mexican subjects.

The researcher, Lilia Prada-León, “initially complained that she didn’t want to study classical music because her Mexican participants don’t listen to that music much,” Parker recalls. “She wanted to do it with mariachi bands, which we may still do sometime later.”

Despite Prada-León's hesitation, the results from her Mexican subjects fit snugly with the results from Americans. “The pattern of results for tempo, mode, and composer were remarkably similar,” the authors write.

Also similar were the emotional ratings that Mexican and American subjects gave the musical selections, as well as the colors themselves. The emotions linked to each piece of music matched the emotions linked to that music's colors. This suggests that music itself doesn't make most people think of color. Instead, music triggers emotion—and that emotion is linked to a certain set of colors in the mind. The results are published in PNAS.

Out of the eight emotions in the original list, only four were needed to explain the results: happy, sad, strong and weak. Happier and stronger colors were associated with upbeat, major-key tunes, while weaker and sadder colors were tied to slower, minor-key pieces.


So what does all this tell us about actual synesthesia?

Palmer says his group has now repeated a version of their experiments with real music-color synesthetes (after finally rounding some up). The results looked different. While non-synesthetes chose different colors depending on the tempo of a piece of music—even if it was the same musical line artificially sped up or slowed down—synesthetes didn't.

"My current opinion is that synesthetes’ color experiences arise from direct mappings from sound to color," Palmer says. In their minds, emotions don't act as the middleman. However, "non-synesthetes’ color associations are indirect and do involve emotional mediation."

But when researchers asked synesthetes to choose the colors that were most "emotionally consistent" with the music, rather than the colors they experienced in their minds, the synesthetes picked out the same colors as everyone else. Additionally, when researchers altered melodies just enough to change them from minor to major, synesthetes—like everyone else—"chose happier colors," Palmer says.

There may be some common ground after all between synesthetes and others. The two groups probably won't agree, though, on the color of the mariachi music playing there.


Images: top by tanakawho (via Flickr); bottom Palmer et al.

Palmer, S., Schloss, K., Xu, Z., & Prado-Leon, L. (2013). Music-color associations are mediated by emotion Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1212562110

"Fool Me Twice, Shame on ME," Says Sea Slug


"Simple" is often a compliment in the human world, used to describe low-fuss dinners or closet solutions. When scientists use "simple" to describe an animal, they mean something more like, "That sac of goo has no business acting clever." An especially simple creature—a sea slug—recently demonstrated that despite its humble resources, it can learn from experience and form new hunting strategies. Smaller goo sacs, beware.

Despite its squishy stature, the sea slug Pleurobranchaea californica is a killer. It roams the sea and swallows whatever appealing morsels are in its way. Being blind, it can't tell how tasty its prey looks—or doesn't.

It can't see, for example, the flashy coloration of the "Spanish shawl" nudibranch (Flabellina iodinea). If it could, it might guess that those bright pink and orange hues are a warning: Flabellina is not nice to eat. It steals stinging cells from its own prey (such as corals and anemones) and stores those stingers in its bristles.

Rhanor Gillette, a neuroscientist at the University of Illinois, Urbana-Champaign, observed that not only do Pleurobranchaea slugs spit out Spanish shawls, but they seem to remember and avoid the animals in the future. To study how well the predatory sea slugs learn their lesson after tasting Flabellina, he and graduate student Vanessa Noboa set up a meet-and-greet between the two species.

In tanks, the large, hungry sea slugs encountered the smaller nudibranchs. Researchers recorded how long it took for Pleurobranchaea to take a taste, then waited for the slugs to change their minds and turn away from their potential prey. (Here's a great video of a Pleurobranchaea attempting to Hoover up a Flabellina, then spitting the animal back out. While the big slug pivots away in disgust, the little one does its "Don't eat me" dance like nobody's watching, which is true.)

On the first day, this interaction happened five times. By the end, most of the Pleurobranchaea slugs were much slower to take a taste of the Spanish shawls, or were ignoring them altogether. Twenty-four hours later, the sea slugs were still reluctant to approach Flabellina. Even after 72 hours, they remembered what they'd learned. Gillette and Noboa report their results in the Journal of Experimental Biology.

Since the predatory slugs seem to sniff something in the water that makes them turn away, the researchers think the noxious Spanish shawls give off a distinctive warning odor.

Gillette says the sea slugs have a decent memory, considering their elementary nervous system. "In these experiments their memory is strong at 48 hours," he says, "and in unpublished work we've seen savings up to a week, so it's not bad." (Oddly, some slugs had to be removed from the experiment because they didn't mind the taste of the stinging Flabellina at all. They sucked it up just like any other food.)

Learning from an unpleasant taste experience, then using that memory to change one's hunting strategy, is "a real cognitive trait," Gillette says—in other words, a "goal-directed use of knowledge." The Pleurobranchaea slugs learned to avoid the smell of Flabellina, although they continued to eat a related, non-stinging species without hesitation.

Being able to change their feeding strategy is a good thing, since these slugs are generalists. Everything in the path of their oozing is a potential meal. "More specialized animals, say sea-slugs that may munch on a particular kind of sponge, may not need to employ such learning abilities," Gillette says. For a hunter like Pleurobranchaea, the decisions aren't so simple.


Noboa, V., & Gillette, R. (2013). Selective prey avoidance learning in the predatory sea-slug Pleurobranchaea californica Journal of Experimental Biology DOI: 10.1242/​jeb.079384

Image: Rhanor Gillette.

How to Convince People WiFi Is Making Them Sick


All it takes is an antenna on a headband. If you've got a breathless video report on the dangers of wireless internet connections, that will help your case. It doesn't take much, though, to turn an ominous hint into a real headache.

Some people consider themselves sensitive to electromagnetic fields. They report symptoms such as burning skin, tingling, nausea, dizziness, or chest pain, and they blame their malaise on nearby power lines, cell phones, or WiFi networks. A recent Slate article described such people moving to a remote West Virginia town where radio-frequency signals are banned. (The town is within the U.S. National Radio Quiet Zone, an area that's enforced to keep signals from interfering with radio telescopes there—telescopes that work because they receive the radio-frequency signals constantly hitting our planet from space.)

There's no known scientific reason why a wireless signal might cause physical harm. And studies have found that even people who claim to be sensitive to electromagnetic fields can't actually sense them. Their symptoms are more likely due to nocebo, the evil twin of the placebo effect. The power of our expectation can cause real physical illness. In clinical drug trials, for example, subjects who take sugar pills report side effects ranging from an upset stomach to sexual dysfunction.

Psychologists Michael Witthöft and G. James Rubin of King's College London explored whether frightening TV reports can encourage a nocebo effect. They recruited a group of subjects and showed half of them a clip from a BBC documentary about the potential dangers of wireless internet. (The BBC later acknowledged that the 2007 program was "misleading.") The remaining subjects watched a video about the security of data transmissions over mobile phones.

After watching the videos, subjects put on headband-mounted antennas. They were told that the researchers were testing a "new kind of WiFi," and that once the signal started they should carefully monitor any symptoms in their bodies. Then the researchers left the room. For 15 minutes, the subjects watched a WiFi symbol flash on a laptop screen.

In reality, there was no WiFi switched on during the experiment, and the headband antenna was a sham. Yet 82 of the 147 subjects—more than half—reported symptoms. Two even asked for the experiment to be stopped early because the effects were too severe to stand.

Witthöft says he expected to see a greater effect in people who had watched the frightening documentary. This wasn't the case overall. Instead, the movie mainly increased symptoms in subjects who described themselves beforehand as more anxious.

"It suggests that sensational media reports especially in combination with personality factors (in this case anxiety) increase the likelihood for symptom reports," Witthöft says.

Plenty of symptoms were reported without the sensationalist TV show, though. The antenna on the head, the researchers' allusion to a "new kind of WiFi," and the instructions to monitor their bodies closely were enough to trigger symptoms in many people who watched the other video.

Witthöft points out that his study would have been stronger if there were a third group of subjects who didn't wear the "WiFi" headband at all, but were simply told to pay attention to their bodies for 15 minutes. This kind of attentiveness might trigger symptoms on its own.

Still, Witthöft says, "I think the high percentage of symptom reports nicely shows how powerful nocebo effects are."

Though the researchers set out to show how irresponsible reports in the media can trigger a nocebo effect, they ended up showing how easy it is to make a person feel sick with just a a prop and a few choice words. Even a National Radio Quiet Zone can't protect against that.


Witthöft, M., & Rubin, G. (2013). Are media warnings about the adverse health effects of modern life self-fulfilling? An experimental study on idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) Journal of Psychosomatic Research, 74 (3), 206-212 DOI: 10.1016/j.jpsychores.2012.12.002

Image: Scott Beale/Laughing Squid (via Flickr)

Happy Blogday! Help Me Rename This Site


Inkfish is three years old today!

One great thing about blogs that doesn't apply to real three-year-olds is that you can change their name and appearance at will. I'm getting tired of "Inkfish"—too mysterious, too many creepy arms. Too much guilt about mistakenly calling octopus arms "tentacles" on occasion.

So I'd like to give the blog a new name and a new look. Below are several directions I'm considering. I hope that you, readers, will weigh in.

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Welcome! You Probably Got Here by Googling Your Juice Cleanse Symptoms
Tagline: Or Searching for Ionic Foot Detox Reviews
Alternate tagline: I Write About Other Stuff Too. Check It Out When You're Less Hazy
Banner art: a weeping woman with her feet in a small tub of brown water. Foregrounded, a glass of kale juice with a party umbrella.
Inspiration: juice cleanses, foot detox, everything else.

Why I Couldn't Hang Out Last Night
Banner art: a blogger on a couch in a dark room, gently lit by the glow of the laptop screen.
Inspiration: purely fictional.

Every Study About Penguins
Banner art: penguins.
Alternate art: not penguins. Irony could increase my readership among hipsters.
Inspiration: penguins, penguins, penguins, penguins, penguins.

The Loom
Banner art: portrait of Carl Zimmer.
Inspiration: trying to lure Bing users who are searching for Carl Zimmer's blog, The Loom.
Potential complication: lawsuit.

Animals with Things on Their Heads
Banner art would be a rotating selection of photos: crabs wearing GPS devices, pigeons carrying cameras, penguins with earmuffs, and this seal.
Inspiration: animal stalkingpigeons.

Girl That Poops Flowers
Alternate title: Most Inconvenient Moments to Have Narcolepsy
Banner art: a mouse that's quiet—too quiet.
Inspiration: unusual internet searches addressed at the help desk.

Adventures in Bodily Fluids: An Ongoing Quest to Make My Grandmother Admit She Doesn't Love Everything I Write
Banner art: the empty vanilla ice cream bowl I considered using to illustrate a story about sperm-eating flies.
Inspiration: see above.

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Please leave your votes in the comments (or just say hello). Thanks for your help, and thanks as always for reading!

What's the Point of Making This Face When We're Scared?


If cartoonists ever pause in their sketching to ponder human evolution, they must feel grateful to the forces that shaped our fear expression. All it takes is a pair of extra-wide eyes to show that a character is freaking out. There may be a point to this expression beyond making artists' lives easier: widening our eyes expands our peripheral vision, and might even help other people spot the cause of our alarm.

"Our lab is interested in the evolutionary origins of emotional expressions," says Daniel Lee, a graduate student in psychology at the University of Toronto—in other words, "why they look the way they do." When we feel afraid, for example, is there a point to stretching out our eyelids and raising our eyebrows to the ceiling?

To explore this question, Lee and his coauthors first asked whether widening our eyes helps us see better. They had 28 volunteers look at a fixed spot on a computer screen while holding their eyes in a neutral expression, an expression of fear, or one of disgust. (Subjects acted out these expressions rather than, say, having a chair pulled out from under them before each trial. Lee points out that emotions themselves may also change our perception, but he wanted to study the effects of widened eyes separate from any psychological effects of fear on the brain. "We coached each participant on how to make fear and disgust expressions based on the Facial Action Coding System," he says.)

Subjects were tested with flashing images on the screen in their peripheral vision. Lee found that people making a disgusted expression—with the eyelids narrowed as in "Ew, get that out of my face"—scored the worst. People making a wide-eyed fear expression scored the best, with a useful field of vision 9% larger than that of people with a neutral expression.

Being afraid, then, may help us gather more visual information about whatever's threatening us in our environment. But does it also help us communicate that threat to our companions?

The researchers next used pictures of models' eyes expressing different emotions to create simplified, graphic eye images. (They didn't use real eyes because those might have conveyed extra emotional information, instead of only varying in wideness.) Subjects saw these eye images flash briefly on a screen, looking toward the right or left by varying degrees. Lee found that when the eyes were wider, subjects had an easier time telling which way they were looking. The results are reported in Psychological Science.


"We believe the widening eyes of fear...[are] a functional response for vigilance toward threat," Lee says. When we're scared, he thinks, widening our eyes helps us to see threats and to communicate their location to our group.

The researchers point out that human eyes are uniquely suited for this kind of communication: we're the only primate with a white sclera (the area outside the iris). In other apes and monkeys, this part of the eye is dark. It's yet another factor that cartoonists, no doubt, appreciate.


Lee, D., Susskind, J., & Anderson, A. (2013). Social Transmission of the Sensory Benefits of Eye Widening in Fear Expressions Psychological Science DOI: 10.1177/0956797612464500

Image: by Tom Check (via Flickr)

Tone-Deaf Birds Disrupt Society, Are Easier to Get into Bed


While male birds are singing elaborate arias and flashing their feathers, it's easy to imagine their female counterparts are unimportant actors. Duller and quieter, all a lady bird has to do is hold still and let one of these frantic performers mate with her. Yet in brown-headed cowbirds, at least, the quiet female keeps the whole society in order. Scientists discovered this by targeting a tiny portion of the female brain and frying it.

Males of the species Molothrus ater use their songs to compete with each other and to woo females. Once a a mating pair forms, they stay faithful to each other for the whole mating season, the male guarding his partner from rivals.

Near the top of the bird brain, a region called nucleus HVC controls females' choosiness toward their potential mates. Scientists at the University of Pennsylvania and Wilfrid Laurier University performed brain surgery on female cowbirds, carefully destroying only this region. Then they put their lobotomized females back into the dating arena to see what would happen.

First, the ladies listened to recordings of male songs. The researchers played tunes sung by a variety of males and observed the females' responses. (When they like what they hear, female cowbirds show it by crouching down in a copulation-ready pose.)

Normal females were choosy, only responding to the highest-quality male songs. Females who'd had brain surgery, though, responded positively to every song.

The researchers wanted to see what effect the females' new, lax attitude would have in cowbird society. So they put post-surgery females, normal females, and males in one big group together. Then they watched.

At first, it looked like nothing was different. Females missing their HVC seemed to act the same as females with intact brains; once they were all together in the aviary, there was no clear difference in how often females approached male birds or in how they "chattered" back at males to encourage their singing.

Nevertheless, something had changed. The other birds in the aviary treated post-surgery females differently. For one thing, females missing their HVC were serenaded by a greater variety of males, even once they'd chosen a mate. Normally, a female who's bonded with a male hears his song almost exclusively. This is a measure of how strong the bond between partners is, says study author David White. Now, with more males bending a female's ear, her pair bond was weaker.

There were other changes too. With the altered females introduced into the group, female birds competed more for mates. And the whole hierarchy of male birds, which is established before the breeding season starts, was disrupted. Male cowbirds sing at each other to show who's dominant. After the HVC-less females came to live with them, the rules about which males were dominant singers shifted significantly.

"The result in this paper turned everything around for us," White says.

Previously, it had seemed to be the male cowbird's responsibility to create a strong bond with his partner. Females appeared to be passive agents in the group. "They don't sing, they don't fight," White says. "They don't, to our eye, do much of anything." Yet when the choosiness was erased from females' brains, the whole group dynamic changed. "Now we could see that it was the female that was playing a much more active role in pair-bonding, and in all sorts of other roles within the social network," White says. Everything depended on her song preferences.

Incidentally, it's not clear why female cowbirds bond with males at all.

Females have likely evolved to pick mates whose songs demonstrate—somehow—that they have the best genes. Then the males keep singing to the females throughout the breeding season, strengthening the bond between them.

Usually, White says, bird couples only form strong bonds when both parents will need to care for the young. But cowbirds "are very bad parents overall" who abandon their eggs in the nests of other birds. The powerful bond between cowbird partners "really makes no sense," White says.

Yet once they're bonded, males direct almost all their singing to their partner and never try to mate with other birds. "They follow each other around, they eat together, he comes when she calls him," White says. If a female dies or disappears, he adds, "her pairmate just becomes a wreck. We call it the widowed male phenomenon."

After the loss of his mate, the male gives up for the season. "He flies around looking for her," White says. To him, at least, the quiet female never seemed unimportant.


Maguire, S., Schmidt, M., & White, D. (2013). Social Brains in Context: Lesions Targeted to the Song Control System in Female Cowbirds Affect Their Social Network PLoS ONE, 8 (5) DOI: 10.1371/journal.pone.0063239

Image: female brown-headed cowbird by JanetandPhil (via Flickr)

Whale Turns Down Its Hearing When Expecting Loud Sounds


We can knit sweaters for oiled penguins, but it's harder to protect whales and dolphins from the harm of having us as neighbors. Loud underwater sounds from activities like sonar and drilling may damage these animals' hearing and even lead to mass strandings. Though we can't chase cetaceans around with homemade earmuffs, we might be able to teach them to tune us out.

Like squinting or letting one's pupil shrink in bright light, some animals can adjust how sensitive their ears are. When we're making loud noises, humans reflexively squeeze the muscles of the middle ear to dampen our hearing. Some bats do the same thing while echolocating.

"Generally speaking, mammals have evolved mechanisms to protect their auditory systems from self-produced intense sounds," write Paul Nachtigall of the University of Hawaii and Alexander Supin of the Russian Academy of Sciences. In 2008, the pair showed that a false killer whale (Pseudorca crassidens) could adjust its hearing while it echolocated. So they set out to see whether the species could also dial down its hearing in response to sounds made by someone else.

They taught their whale (a female, originally caught in the wild and now thought to be 30 or 40 years old) that hearing a quiet warning sound meant a louder sound was coming soon. The subject wore suction-cup electrodes on her head during the experiment. Waiting at an underwater listening station, she first heard a series of tones while the electrodes measured which ones her ears responded to. Then, a variable amount of time later, she heard a sudden loud sound (170 decibels).

Over hundreds of trials,* the researchers saw that the whale learned to anticipate the loud sound. If it came within 35 seconds of the warning sound starting, the whale was able to desensitize her ears before it played. (With a longer delay, her response wasn't as strong.) The authors report their results in the Journal of Experimental Biology.

Nachtigall can't say how a whale turns down its hearing. "No one knows for sure how the cetacean middle ear works," he says. Whales don't have eardrums like humans or other land animals, he says, because the sounds they hear must travel through tissue instead of air. So his whale subject probably doesn't squeeze her ear muscles to dampen sound, as a human or bat would. He speculates that it's more likely a top-down control from the brain.

However she does it, the whale can make her ears less sensitive when she knows a loud sound is coming soon. The biggest decrease in her hearing sensitivity was about 13 decibels. That's "about what your hearing changes if you stick your fingers in your ears," Nachtigall says. If you—or the whale—are trying to protect your hearing from a loud noise, he says, "That helps. This would help."

When humans must make a racket underwater, it's possible that we could help whales and other animals by making quieter warning sounds beforehand. This could teach the animals to anticipate the sound and "plug" their ears.

Since he's only studied one animal so far, Nachtigall doesn't know how the abilities of other marine mammals to desensitize their ears compare. "To ask whether [warning sounds] would prevent whale hearing damage is sort of like asking whether ear plugs would prevent deafness in people who work next to jet engines," he says. "I believe the possibility is great, but there are more questions to be answered."


Image: by MichiKimmig (Flickr)

Nachtigall, P., & Supin, A. (2013). A false killer whale reduces its hearing sensitivity when a loud sound is preceded by a warning Journal of Experimental Biology DOI: 10.1242/​jeb.085068

*If you're wondering how one convinces a whale to participate in so many trials, the answer is "fish reinforcement."