One of the many things I love about teaching psychology is that I can learn something new about the field—about our humanness—just about anywhere. I am currently reading Skeleton Keys by Brian Switek (2019), a science writer and bone geek. Exploring the origins of our bones, this book is a fascinating history. Any history that starts a few hundred million years ago—as this one does—reminds me how improbable our existence is. It is improbable that mammals exist, that primates in particular exist, that humans exist, and, lastly, that I, specifically, exist. With an incomprehensible timeline that is measured in millions of years, I can’t help but think—in the greater scheme of things—how small I am. While that millions-of-years perspective didn’t stop me from being irritated with some of my fellow drivers on my morning commute, I did think about that dinosaur who one day felt irritated with their fellow dinosaurs when travelling to wherever dinosaurs travelled. You have my empathy, dinosaur. In a brilliant example of burying the lede, I’m actually writing about where the three little bones in the middle ear come from, as I just learned from Skeleton Keys. Stick with me. Protomammals—a group of animals who were precursors to mammals—had jaws comprised of a number bones. Visit the Wikipedia page for Dimetrodon, a protomammal that lived almost 300 million years ago. On that Wikipedia page, scroll down to the drawings of the skull. In the lateral view, notice the quadrate bone at the back of the upper jaw and the articular bone in the back of the lower jaw. Over time—and by “time” I mean millions of years—those bones shrunk in creatures that followed Dimetrodon, but did not disappear. The quadrate evolved into the incus (anvil), and the articular evolved into the malleus (hammer). The stapes (stirrup) had a different origin, but same idea. It was a small bone on top of the hyoid bone in the neck of protomammals (Maier & Ruf, 2016). Press your fingers into the skin right in front of your ear. Open and close your jaw. This is where your upper and lower jaws meet. Those tiny bones of the middle ear are right behind that joint.   References Maier, W., & Ruf, I. (2016). Evolution of the mammalian middle ear: A historical review. Journal of Anatomy, 228(2), 270–283. https://doi.org/10.1111/joa.12379 Switek, B. (2019). Skeleton Keys. New York City: Riverhead Books. ... View more

Because the perception of color is inherent to our experience, it’s difficult to know what someone else’s perception of color is like. People with total color blindness (either monochromacy or achromatopsia) (National Eye Institute, 2015) or color deficiency – can’t know what someone with complete color vision sees. And people with complete color vision can’t know what someone with total color blindness or color deficiency sees. In an article about what it is like to be a woman who is red/green color blind*, Zoe Dubno (2019) tells us about a free app that manipulates color to show us what everyone else is seeing: Color Blind Pal (Android/iOS/Mac). If your students have one of these three types of color blindness, the app will shift the hue of colors to make those colors easier to see. Protanopia/protanomaly (cannot see any red/reduced sensitivity to red) Deuteranopia/deuteranomaly (cannot see any green/reduced sensitivity to green) Tritanopia/trianomaly (cannot see blue/reduced sensitivity to blue) For your non-color blind students who are, say, future software builders, website designers, graphic designers, interior designers or who will ever have a need to create a graph or do a presentation, they should know what almost 10% of their audience (National Eye Institute, 2015) will see. You can give your students this information from the National Eye Institute (2015): Red/green color blindness Protanopia: “Red appears as black. Certain shades of orange, yellow, and green all appear as yellow.” Protanomaly: “Red, orange, and yellow appear greener and colors are not as bright.” Deuteranopia: Red looks brownish-yellow; green look beige. Deuteranomaly (most common): “Yellow and green appear redder and it is difficult to tell violet from blue.” Blue/yellow color blindness Tritanopia (very rare): “Blue appears green and yellow appears violet or light grey.” Trianomaly: “Blue appears greener and it can be difficult to tell yellow and red from pink.” Or your non-color blind students can see the effects of color blindness for themselves in the Color Blind Pal app.  Or your color blind students who are, say, future software builders, website designers, graphic designers, interior designers or who will ever have a need to create a graph or do a presentation, can use the Color Blind Pal app to shift colors into a range they can better see.  Instructions on how to use the Color Blind Pal app are at the end of this blog post. Why is it that a red deficiency results in an inability to distinguish red from green and vice versa, and why is it that a green deficiency results in an inability to distinguish green from red? Follow the link to this image that shows the light wavelengths and how many photons (packets of lightwaves) each cone captures. Notice how much the red and green cones overlap in terms of their sensitivity to the wavelengths of light. For someone who is lacking green sensitivity, for example, their spectrum shifts toward red, making telling the difference between red and green more difficult. Conversely, for someone who is lacking red sensitivity, their spectrum shifts toward green, also making telling the difference between red and green more difficult. Why so much overlap between red and green cones? It looks like red and green cones used to be different alleles of the same gene. And this is still true among New World primates. The continents split 50 million years ago separating what would become New World primates from Old World primates. Around 40 million years ago, in Old World primates what was the green/red gene duplicated, allowing one gene to specialize in creating red cones and the other to specialize in creating green cones. New World primates haven’t had this gene duplication and all remain dichromats (essentially, they’re red/green color blind), except for some females. Since the gene with red/green alleles resides on the X chromosome (and gene for blue cones on chromosome 7), a male New World primate has blue (chromosome 7) and either green or red (he only has one X). A female New World primate has blue (chromosome 7), and, with two Xs, she can have two greens, two reds, or a green and red. In the latter case, she is a trichromat (White, Smith, & Heideman, n.d.). The Ishihara Test After your students have had a chance to explore the Color Blind Pal mobile app, visit a website that displays examples from the Ishihara Test for color blindness, such as this one at colormax.org. Zoom in so that only one test item is displayed at a time. Your students who are not color blind can simulate the different forms of color blindness to see how the number disappears. They can then change the settings in the app so that the app thinks they have, say, deuteranopia, to see how the app changes the colors to make the number more distinctive. Your students who are color blind, using the app set to their form of color blindness may see the number where they hadn’t before.   ******<Start instructions>****** Instructions on how to use the Color Blind Pal mobile app Install the app by downloading it from Google Play (Android) or the App Store (iOS). When it asks, give the app permission to access your camera. If you are not color blind or color deficient: Click on the “i” icon, then click on “Color blindness type.” Choose one of the five “Simulate” options. Start with “Simulate deuteranomaly” (reduced sensitivity to green and the most common form of color blindness), then tap the back arrow. At the top of the screen, you can toggle between “Inspecting Color” which names the color in the middle of the screen and “Filtering Colors.” (Play around with “Inspecting Color” first, if you’d like.) Switch to “Filtering Colors.” Make sure “Shift” is selected at the bottom of the screen. You are now seeing what someone with deuteranomaly sees. Use the app to look at a range of colors, especially green and orange. Compare violet and blue. In the settings, change the “color blindness type” to “Simulate deuteranopia” (green blindness), and tap the back arrow. Look at those same colors again. How does lacking the ability to see any green (deuteranopia) compare to being green-deficient (deuteranomaly)? Change the “color blindness type” again to simulate the other forms of color blindness: protanopia (cannot see red), protanomaly (red-deficiency), tritanopia (cannot see blue). How do colors look different when simulating deuternopia compared to protanopia? If you are color blind or color deficient: Click on the “i” icon, then click on “Color blindness type.” Choose the type of color blindness that is closest to yours: protanopia (red), deuteranopia (green), or tritanopia (blue), then tap the back arrow. If you're not sure which form you have, start with deuteranopia (also covers deuteranomaly, the most common type of color blindness). At the top of the screen, you can toggle between “Inspecting Color” which names the color in the middle of the screen and “Filtering Colors.” (Play around with “Inspecting Color” first, if you’d like.) Switch to “Filtering Colors.” Make sure “Shift” is selected at the bottom of the screen. The app will “shift" hues away from colors that are hard to distinguish toward colors that are easier to distinguish.”   At the bottom of the screen, select “Filter.” Everything will appear gray except for the color you chose on the slider. How do the colors change for you? What looks different now? ******<End instructions>****** *Color blindness vs color deficiency. Technically, the only people who are color blind are those with no color vision at all. Everyone else has different degrees of color deficiency. However, color blindness is in common use to mean any degree of color deficiency, I will use color blindness in this post in that way.   References Dubno, Z. (2019, February 5). Letter of recommendation: Color blind pal. The New York Times Magazine. Retrieved from https://www.nytimes.com/2019/02/05/magazine/letter-of-recommendation-color-blind-pal.html?partner=rss&emc=rss National Eye Institute. (2015). Facts about color blindness. Retrieved February 13, 2019, from https://nei.nih.gov/health/color_blindness/facts_about White, P. J. T., Smith, J., & Heideman, M. (n.d.). The evolution of trichromatic vision in monkeys. Retrieved February 17, 2019, from https://lbc.msu.edu/evo-ed/pages/primates/index.html ... View more

You can buy a good pair of bone conduction headphones for under $150. Some of your students may have seen them or own a set. Here’s a little information to add to your next Intro Psych hearing lecture, or at least some information to hold onto in case a student asks. If you teach Biopsych, you can dig even deeper into this topic – or have your students do the digging. Bone conduction headphones, such as Aftershokz Trekz Air, send vibrations through, well, bone. The headphones speakers are generally positioned against the cheek bone or upper jaw bone right in front of each ear. The cheek bones carry the vibrations through to the temporal bone – the bone that surrounds the cochlea. While the specifics are still under investigation, we know that these vibrations cause the cochlear fluid to move, triggering the cilia that send their messages to the auditory cortex where we hear sound. It could be that the bone vibrations cause the fluid in the cochlea to move due to a change in pressure, the vibrations in the bone put pressure on the walls of the cochlea causing them to compress, or the vibrations in the bone could cause waves in the cerebrospinal fluid in the skull thereby causing waves in the cochlea (Dauman, 2013). Or all three. All of those routes explain how someone with middle ear damage can hear through bone conduction. The vibrations bypass the bones of the middle ear and affect the cochlea directly. Bone conduction hearing devices (previously called bone anchored hearing aids) are for people with issues with their outer or middle ears. These devices can either be surgically implanted with a speaker attached by magnet or just temporarily attached with adhesive (Hearing Link, 2017). The vibrations produced by bone conduction headphones also cause vibrations in the skin and cartilage of the outer ear as well as vibrations in the temporal bone of the skull. Those vibrations cause air to move in the outer ear, triggering the bones of the middle ear to move, and so on, resulting in sound. This may not contribute much to what we hear through bone conduction, but it contributes more if we wear ear plugs with our bone conduction headphones. That brings us to the occlusion effect (Dauman, 2013). While you may not be familiar with the occlusion effect (I wasn’t), everyone with some amount of hearing has experienced it. While talking, plug your ears with your fingers. Your voice will sound up to 20 decibels louder (Ross, 2004).   We hear our own voices through bone conduction. With our outer ears open, the vibrations that come through the bone can vibrate on out through the outer ear. With our outer ears plugged, the vibrations cannot escape and so reverberate back through the middle ear, amplifying our voices. This is one of the reasons some people don’t like (unvented) earmold hearing aids; they completely block the ear canal making our voice sound funny (Ross, 2004). Most earmold hearing aids now come with a vent – an opening that allows the vibrations caused by our voices to escape. Why use bone conduction headphones? There are several advantages to using bone conduction headphones (Banks, 2019). If you are walking, running, or biking on the open road, bone conduction headphones allow you to listen to your tunes without blocking your ear canal. You’ll have a greater chance of hearing that car coming up behind you, but, of course, all of the research on attention tells us that you still may not attend to the sound of the car. Or you may not hear the car at all if the sound of it is masked by whatever you’re listening to through your headphones (May & Walker, 2017). In terms of this sort of safety, bone conduction headphones are likely not worse than any other kind of headphone or speaker (Granados, Hopper, & He, 2018). If you use earmold hearing aids, you can use bone conduction headphones with them. If you are a scuba diver, you can use a bone conduction microphone and headphones to both speak and listen underwater (see for example Logosease). If you have tinnitus, bone conduction headphones can provide auditory stimulation to the cochlea that may reduce tinnitus while allowing you to still have a conversation in, say, a work environment (British Tinnitus Association, n.d.; Schweitzer, 2018), although the research here is scant (Manning, Mermagen, & Scharine, 2017). Can bone conduction headphones produce hearing loss when listening at loud volumes just like regular headphones can? After scouring journals and reading opinions from all corners of the internet, my conclusion, pending further evidence, is a tentative and cautious affirmative; bone conduction headphones can cause hearing loss. Anything that can produce loud sounds, including regular headphones cranked up to a high volume, causes hearing loss by producing tsunamis that damage the cilia in the cochlea. Since bone conduction headphones are also causing waves in the cochlea, it stands to reason that waves caused by bone conduction could also reach tsunami strength. But, then again, maybe bone conduction cannot produce those kind of waves. Some research here would be nice. If you know of any, please let me know!   References Banks, L. (2019). Best bone conduction headphones of 2019: A complete guide. Retrieved February 11, 2019, from https://www.everydayhearing.com/hearing-technology/articles/bone-conduction-headphones/ British Tinnitus Association. (n.d.). Sound therapy (sound enrichment). Retrieved February 11, 2019, from https://www.tinnitus.org.uk/sound-therapy Dauman, R. (2013). Bone conduction : An explanation for this phenomenon comprising complex mechanisms. European Annals of Otorhinolaryngology, Head and Neck Diseases, 130(4), 209–213. https://doi.org/10.1016/j.anorl.2012.11.002 Granados, J., Hopper, M., & He, J. (2018). A usability and safety study of bone-conduction headphones during driving while listening to audiobooks. Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 62(1). Hearing Link. (2017). Bone conduction hearing devices. Retrieved February 11, 2019, from https://www.hearinglink.org/your-hearing/implants/bone-conduction-hearing-devices/ Manning, C., Mermagen, T., & Scharine, A. (2017). The effect of sensorineural hearing loss and tinnitus on speech recognition over air and bone conduction military communications headsets. Hearing Research, 349, 67–75. May, K., & Walker, B. N. (2017). The effects of distractor sounds presented through bone conduction headphones on the localization of critical environmental sounds. Applied Ergonomics, 61, 144–158. Ross, M. (2004). Dr. Ross on hearing loss. Retrieved February 11, 2019, from http://www.hearingresearch.org/ross/hearing_loss/the_occlusion_effect.php Schweitzer, G. (2018). Bone conduction headphones for hearing loss and tinnitus. Retrieved February 11, 2019, from https://rewiringtinnitus.com/trekz-titanium-bone-conduction-headphones/ ... View more

Perceptual illusions are not only great fun, they also remind us of a basic truth: Our perceptions are more than projections of the world into our brain. As our brains assemble sensory inputs they construct our perceptions, based partly on our assumptions. When our brain uses rules that normally give us accurate impressions of the world it can, in some circumstances, fool us. And understanding how we get fooled can teach us how our perceptual system works.   A case in point is the famed Müller-Lyer illusion, for which the Italian visual artist Gianni Sarcone gives us two wonderful new examples. https://www.giannisarcone.com/3-MEDIA_Images/Muller_lyer_star_OR2.gif  https://www.giannisarcone.com/wp/wp-content/uploads/2017/10/Muller_Lyer_waves_S.gif   Many more informative examples can be found amid the 644 pages of the new Oxford Compendium of Visual Illusions. There I discovered a fascinating phenomenon reported by Gettysburg College psychologist Richard Russell.   First (with Professor Russell’s kind permission from his earlier article in Perception) a question: In the pair of Caucasian faces, below, which looks to be the male, and which the female? Do you (as did I) perceive the left face as male, the right face as female?   Many people do, but in actuality, they are the same androgynous face (created by averaging Caucasian male and female faces), but with one subtle difference: the researchers slightly darkened the skin (but not the lips or the eyes) in the left face and lightened the skin in the right face. Why? Because worldwide and across ethnic groups, Russell and others report, women’s skin around the lips and eyes tends to be lighter than men’s. And that means more contrast between their skin and their lips and eyes.   That natural, subtle facial sex difference enabled Russell to recreate what he calls “the illusion of sex” with a second demonstration. This time, he left the skin constant but lightened the lips and eyes of the left face, making it appear male, and he darkened the lips and eyes of the right face, increasing the contrast, making it appear female. Russell suggests that this helps explain why, in some cultures, women use facial cosmetics. Lipstick and eye shadow amplify the perceived sex difference, he notes, “by exaggerating a sexually dimorphic attribute—facial contrast.”   ... View more

I didn’t start covering hearing in my Intro Psych course until the earbud-style headphones became popular. When I heard music emanating from a student’s earbuds from the back of the room, I knew it was time for us to have a conversation. In the cochlea, the stereocilia closest to the oval window are the ones responsible for hearing high-pitched sounds. Exposure to loud sounds causes a tsunami to rush over those stereocilia, causing them to bend over farther than they are supposed to resulting in permanent damage (Oghalai, 1997). The Center for Hearing Loss Help has a nice image of a bundle of pristine stereocilia and a bundle of damaged cilia. In fact, this is an interesting article on diplacusis, where one ear hears a pitch that is just above or just below the pitch heard by the other ear (Center for Hearing Loss Help, 2015). In class, after walking students through the structure and workings of the ear, I go to this webpage (Noise Addicts, n.d.) that has 3-second sound files of pitches ranging from 22 kHz down to 8 kHz. I start with the 22 kHz, which none of my students can hear, and then move to lower pitches one by one. I cannot hear them until I get down to about 14 kHz. Fifty years of being exposed to sound, with the last 16 years spent in a noisy urban environment – and more than one rock concert – has likely taken its toll. I have friends in their 70s who have spent their lives in a quiet town who have no problem hearing 17 kHz. Of course exposure to loud sounds is not the only factor that can affect hearing loss for high-pitched sounds, but it is a common factor. Some time ago, I had a student who knew that he had some hearing loss, but he had no idea of the extent of it. When I played the sounds in class, he was stunned to see students reacting to the high-pitched sounds that he couldn’t hear. The first frequency he heard was a mere 8 kHz. He immediately made an appointment with an audiologist. He was (just barely) young enough that he qualified for a special program that got him hearing aids for free. The first time he was in class after getting them, he told me that he was floored by how much he could hear – and how much he hadn’t been hearing. Another student who spent a couple years working as a bouncer at a (very loud) club was 23 years old, and the first frequency he heard was 12 kHz. In Mary Roach’s book Grunt, she writes that the problem with most hearing protection is that not only does it protect against loud sounds, but it also makes it hard to hear softer sounds. This is especially problematic for combat soldiers. They need to protect their hearing in case of a sudden explosion or gunfire, but they need to be able to hear what their fellow soldiers are saying. There are now ear cuffs that protect against loud noises but also amplify quieter sounds. In this 3-minute YouTube video, Roach describes the hearing problem and how these new ear cuffs work. A student of mine, who is in the army, said he got to try out the ear cuffs – although not in combat, and he was very impressed with how well they worked. Video Link : 2162 Knowing how their ears work can help students make informed decisions about how they would like to treat their ears. With that knowledge, students may make better decisions that will affect them for their rest of their lives. References Center for Hearing Loss Help. (2015). Diplacusis -- the strange world of people with double hearing. Retrieved from http://hearinglosshelp.com/blog/diplacusisthe-strange-world-of-people-with-double-hearing/  Noise Addicts. (n.d.). Hearing test -- can you hear this? Retrieved from http://www.noiseaddicts.com/2009/03/can-you-hear-this-hearing-test/  Oghalai, J. S. (1997). Hearing and hair cells. Retrieved November 4, 2017, from http://www.neurophys.wisc.edu/auditory/johc.html  ... View more

As I draft this on Mother’s Day I think of my mother, who blessed me with nurturing and many other gifts, including, alas, the gift of her hearing loss . . . which she, in turn, had received from her mother. I began my memoir, A Quiet World: Living with Hearing Loss, with this recollection: On one of those treasured visits to my parents' home on Bainbridge Island, Washington, I use a magic pad to communicate with my eighty-year-old mother, who four years previously took the final step from hearing-impaired to deaf as she gave up wearing her by then useless hearing aids. “Do you hear anything?” I write. “No,” she answers, her voice still strong although she cannot hear it. “Last night your Dad came in and found the T.V. blasting. Someone had left the volume way up; I didn't hear a thing.” (Indeed, my father later explained that he recently tested her hearing by sneaking up while she was reading and giving a loud clap just behind her ear. Her eye never wavered from the page.) What is it like, I wonder. “A silent world?” “Yes,” she replies, “it's a silent world.” As with Mother, so, I expect, with me. I have known for many years that I am on a trajectory toward the same deafness. When tested as a teenager, my hearing pattern mimicked Mother's—an unusual “reverse slope” pattern of good hearing for high-pitched sounds and poorer hearing for low-pitched sounds (making soft male voices harder to discern than higher female voices). From upstairs, I can hear the high-pitched microwave oven timer, though my wife, Carol, snuggled beside me in bed, cannot. But I cannot recall ever hearing an owl hoot. Carol touches my leg at each hoot: “There, can you hear it?” I hear nothing.   A quarter century and more later, I continue on that trajectory, unable now (with my hearing aids out) even to hear my wife’s voice from the adjacent pillow, unless she speaks directly into my ear. In daily life I mostly cope well enough, thanks to powerful digital hearing technologies that my mother never knew. Even so, I struggle to hear amid noise—at a party, in a restaurant—or when a questioner is across a room. Like all who suffer this invisible disability, I strain to hear. I move closer. Or, with a smile and a nod, I fake hearing.   On the brighter side, the hearing loss plague has also given me an added life purpose—supporting people with hearing loss by advocating for a “hearing loop” transformation in how America provides listening assistance in public places (through this website, through three dozen articles such as this one, and via nearly 20,000 e-mails). And this advocacy led me to four years representing people with hearing loss on the advisory council of NIH’s National Institute on Deafness and Other Communication Disorders.   There I was privileged to meet and hear from some world class hearing researchers, including the University of Iowa physician-geneticist Richard Smith, who is amassing data on the genes of many thousands of people with hearing loss. When I showed him my audiogram—my profile of hearing loss at various frequencies—he guessed that I carry a mutation on the WSF1 gene, and offered to confirm that.   So I sent in my spit tubes, and last week Smith confirmed: “You have DFNA6/14 hearing loss caused by a mutation in WFS1.”   In psychological science, we teach our students that complex traits, such as intelligence or personality, are the product of “many genes having small effects.” So this is my reminder that some important traits and medical conditions are predisposed by single genes (which my siblings and I each had a 50% chance of inheriting—with my older brother and I, among the four of us, drawing the unlucky cards).   If so, I asked: Is there not some hope that gene editing, such as with the new CRISPR technique, could prevent future hearing loss in children or young adults who carry the gene?  Yes, Smith tells me—this is, indeed, his lab’s exciting aim. Moreover, they plan to conduct the experiment by attempting the gene therapy on but one ear of each volunteer, thus enabling the other ear to serve as what we psychologists call a “within subjects control condition.”   In the meantime, I’m content to be the person Dr. Seuss described in You're Only Old Once!            You'll be told that your hearing's so murky and muddy,            your case calls for special intensified study. They'll test you with noises from far and from near and you'll get a black mark for the ones you can't hear. Then they'll say, "My dear fellow, you're deafer than most. But there's hope, since you're not quite as deaf as a post." ... View more

One of my favorite sources for examples of psychological concepts are comic strips. Some of them get worked into lectures, others show up on exams, and sometimes I’ll offer them for a couple points extra credit, especially for new comics that harken back to content covered earlier in the course. Here are some May 14, 2017 comic strips that may be worth adding to your stable of examples. The Betty comic strip gives us a wonderful example of change blindness. Junior, Betty’s son, is dinking around on his phone while explaining his generation’s amazing ability to multitask. During his explanation, Betty calls in her husband to take her place. When Junior’s attention is returned to his parent, he sees his dad and is completely unaware that he had replaced his mom. In Frank and Ernest Frank has a young person working out on his farm. The young person, upon hearing “crop,” thinks cropping photos instead of crops that are planted. For someone who spends a lot of time in the digital world instead of a farming world, that person would be primed to interpret “crop” as photo manipulation. Frazz gives us commentary on the positive reinforcement provided by smartphones. Pick up your smartphone to get a jolt of pleasure in some form – text messages, phone calls, games, social media updates. Caulfield, the boy in the strip, says that his dad “calls them dopamine pumps.” (If you want to dive deeper into smartphone use, I wrote a post on stress and smartphones a few months ago.) Bonus comic strip. My favorite classical conditioning comic strip comes from Lio (November 14, 2009). A monster replaces Pavlov’s dogs, “Monsta Treats” replace meat powder, and the sound of a ripping bag replaces the tone. Do you have any favorite comic strips that illustrate psychological concepts?   ... View more

After covering sensation and perception, take students back to 2015. In case you missed it, this was the image that blew up social media in February of that year. Viewers were divided into two camps. Some saw the dress as blue/black while others saw it as gold/white. These discussions were not about whether a color was more blue or more purple. People were talking about very different perceptions. Friends and family got into arguments because each camp thought they were being gaslighted by the other. [Side note. The term gaslight, in this context, comes to us from a 1938 play which became a 1944 movie.] What color is the real dress? Blue/black. But before the blue/black perceivers cheer for being right, the image of The Dress that falls on our retinas is more complicated than that. It turns out that both the blue/black and gold/white perceivers are right, that is, in terms of which light waves our eyes pick up. Oh. And if you perceive it as blue/brown, you’re not alone, but there aren’t that many of you. But first, why such different perceptions? Our sensation and perception colleagues identified an assumption that our brains had to make. Some of us assumed that The Dress was lit by artificial, yellow light, the kind of light we get indoors. Others of us assumed that The Dress was lit by natural, blue light, the kind of light we get outdoors. When we assume yellow light, our brains subtract yellow from the light wave data our eyes send to our brains. With the yellow removed, The Dress is perceived as blue/black. When we assume blue light, our brains subtract blue from the light wave data. With blue removed, The Dress is perceived as gold/white. Where does blue/brown come from? Those perceivers are splitting the difference. They’re subtracting a little yellow and a little blue. ASAP Science did a nice 2-minute video on how this – color constancy – works. Video Link : 2015 A closer look at The Dress You can show students exactly what their eyes are seeing, before the brain subtracts a color. On your classroom computer, right-click on the photo of this dress, and select “Copy image address.” Visit the LunaPic website. In the “Open from URL” box, paste the image address. On the far left side of the page you will see a toolbar. Click anywhere over there to enter editing mode. From that toolbar, choose the eyedropper; it’s the ninth icon from the top. Click anywhere on The Dress to see the color of that spot displayed at the top of the page. Click the eyedropper again and choose another spot. When you click on a blue/white band, the color is actually a slate gray. If our brains subtract yellow, we perceive the color as bluer than it is. If our brains subtract blue, we perceive the color as whiter than it is. Use the eyedropper to sample from the black/gold bands. They are a goldish brown. If our brains subtract yellow, we perceive the color as black. If our brains subtract blue, we perceive the color as yellow-gold. Who is more likely to perceive it one way and not another way and why? But none of that answers the question of why some people are more likely to assume yellow light while others are more likely to assume natural light. One hypothesis is that those who spend more of their day inside under artificial lights are more likely to subtract yellow and see a blue/black dress. Those who spend more of their day outside or inside spaces with a lot of natural light – think skylights and large windows – are more likely to subtract blue and see a gold/white dress. Survey research has found that “[o]lder people and women were more likely to report seeing ‘The Dress’ as white and gold, while younger people were more likely to say that it was black and blue” (Cell Press, 2015). Ask your students to work in pairs or small groups to generate some hypotheses as to why this is the case. Ask volunteers to report their hypotheses. For example, is it a cohort effect for age? Did older people spend more of their childhoods outdoors than today’s youth and therefore more likely to assume blue light? Teenagers are also more likely to be “owls.” Psychological scientist Pascal Wallisch reasoned that “owls” – people who get up late and go to bed late – would experience more yellow light and, thus, would be more likely to perceive The Dress as blue/black. Conversely, he expected “larks” – people who get up early and go to bed early – would experience more blue light and, thus, would be more likely to perceive The Dress as gold/white. He found a statistically significant difference between the owls and larks in their perceptions of The Dress, but the differences weren’t huge. In other words, it appears that this is one factor, but not the only factor, that influences our assumptions about the lighting (Wallisch, 2017). Recap Remind students that color does not exist outside of our brains. Outside, it’s light waves. Our eyes convert those light waves into neural signals. Our brain takes those neural signals and uses them in combination with other factors, like the surrounding colors and assumptions about the environment, to create the color that we see.   ... View more

My friend and psychology colleague, Sue Frantz, alerted me to the pride the University of Kansas athletic department took this week in setting a Guinness World Record—with a 130.4 decibel crowd roar during their men’s basketball team’s come-from-behind win over West Virginia. That took my mind to my hometown Seattle Seahawks’ pride on having the loudest outdoor sports stadium, thanks to its “12th Man” crowd noise—which has hit a record 137.6 decibels . . . much louder than a jackhammer, noted hearing blogger Katherine Bouton.  As I mentioned in earlier blog post, with three hours of 100+ decibel game sound, “many fans surely experience temporary tinnitus—ringing in the ears—afterwards . . . which is nature warning us that we have been baaad to our ears. Hair cells have been likened to carpet fibers. Leave furniture on them for a long time and they may never rebound. A rule of thumb: If we cannot talk over a prolonged noise, it is potentially harmful.” Coincidentally, Sue Frantz’s Highline College is just 17 miles from Seahawks stadium, where, she tells me “my former postal carrier ruptured his eardrum. He said he felt the sound wave move from one end of the stadium to the other, and when it bounced back, he felt a sharp pain in his ear that faced that end of the stadium. His eardrum never recovered; his hearing loss was permanent.” The hearing aid industry may welcome the future customers whose hearing decline is hastened by such toxic noise. But for the University of Kansas and my Seahawks, these disability-enhancing Guinness Records are matters for concern, not boasting. ... View more

Open your discussion of sensation and perception by showing students this image. Note the white on the clear bulb where the light is reflecting. Our eyes detect white, but our brains know that those white spots aren’t really white. Based on past experience, our brain perceives the white as merely reflections of light. Image source: https://www.pexels.com/photo/clear-glass-light-bulb-75427 Next, show students this photo. Image source: http://cheezburger.com/8985651968/shiny-legs-optical-illusion-paint-whats-making-these-legs-look-so-shiny     It’s not quite The Dress, but this is still pretty cool. Like many people, what you see are shiny legs. Do they look like they are covered in a hard, clear plastic? But what if I told you that there is no plastic. It’s just strategically placed white paint? If you saw shiny legs, you were perceiving the white as reflected light, as you rightly did with the light bulb. Once you’re told the white is paint, the shininess disappears, and you are just left with, well, white paint. ... View more

Originally posted on September 15, 2016. With thanks to Christopher Platt (NIDCD Director of Hearing and Balance programs), here’s a simple demonstration of our super-speedy vestibular system. As you have surely noticed, if you slip, your vestibular sensors automatically, in a microsecond, direct your skeletal response—well before you have consciously decided how to right yourself. Our vestibular sense is even faster than our visual sense. Try this, suggests Platt: Hold one of your thumbs in front of your face, then move it rapidly right to left and back. Notice how your thumb blurs. (Your vision isn’t fast enough to track it.) Now hold your thumb still and swivel your head from left to right. Voila! Your thumb stays in focus, because your vestibular system, which is monitoring your head position, speedily moves the eyes. Head moves right, eyes move left. Vision is fast, but the vestibular sense is faster. ... View more

This extinction illusion (Hermann grid variation) has been making the rounds on social media courtesy of a Facebook post by psychological scientist Akiyoshi Kitaoka. There are 12 black dots in this grid. Most people cannot see them all at once. The illusion itself first made an appearance in a 2000 journal article by Ninio & Stevens. Check out their paper for other illusions. The larger lesson for your students: Our senses, including vision, allow our brains to create a representation of the world around us. Our senses do not allow our brains to generate a perfect replication of the world. For students who want to know why the illusion works, well, that’s a little more challenging. The short answer is that our retinas are hard-wired to send the clearest, sharpest signals to the brain. Receptor cells that get the strongest signal block out the weaker signals. Those dots in the periphery get blocked by the grey that surround them thanks to the sparser rods in the periphery. For the longer answer, read up on lateral inhibition. Wikipedia provides a nice summary. (Yes, lateral inhibition is also used to explain Mach bands.) If you want to wade into this even deeper with your students, Wesley Jordan (St. Mary’s College of Maryland) has created a class activity that should help students understand lateral inhibition.   References Ninio, J. & Stevens, K.A. (2000). Variations on the Hermann grid: An extinction illusion. Perception, 29, 1209-1217. ... View more

What makes synesthesia such a powerful lecture topic in the Intro Psych sensation and perception chapter is that it’s a beautiful illustration of how our experience is merely a representation, and just one representation, of the world around us. The neuroscientist David Eagleman provides a nice introduction to synesthesia in this two and a half minute video. Video Link : 1751 Years ago in class, after I concluded my lecture on synesthesia, a young woman in the back of the room raised her hand. She said she didn’t know her experience of the world was different from everyone else’s until a friend of hers took my class a year earlier. She said a group of them were standing around when he started talking about this cool thing called synesthesia that he learned about that day in his Intro Psych course. He explained that the most common form is seeing sounds where sounds produce color, like a filter has been applied to vision. My current student said to her friends, “Doesn’t everybody experience that?” They all stopped and looked at her. At the age of 18, she learned that she was a synesthete. I made the same error once in class. After talking about synesthesia, I said it’s like when you’re drifting off to sleep and a sudden noise causes a black and white pattern to flash in your vision – sound produces a visual sensation. My students looked at me blankly. Apparently I was the only one with such an experience. My visual experience used to happen pretty regularly, probably a few times a week, but now it’s a rare occurrence, probably once every few months. In any case, I learned that it’s non-existent in many, at least amongst my students that term. I suppose this assumption is a kind of extension of the false consensus effect. We not only assume that others share our beliefs and attitudes, but that others share our sensory experiences. There is research evidence that suggests we are all born synesthetes (see for example Wagner and Dobkins, 2011), and as we mature through infancy and childhood our senses begin to specialize, much like how infants can produce sounds used in all languages only to become specialists in their native language or languages as they develop.   Exploring vision in non-human animals helps students appreciate that their own sensory experiences may be very different from others. For example, dogs have two kinds of cones in their retinas; they detect yellow and blue. That may make them roughly equivalent to humans who have red-green color blindness (Wolchover, 2012). And birds? They have four kinds of cones, the fourth allows them to see ultraviolet light. It’s been posited that the ability to see UV light allows some songbirds to better see each other as their plumage glows with UV light and that raptors can better track prey that leave a urine trail that also glows with UV light. There’s reason to believe that the jury is still out on both of those hypotheses (see for example, Lind, et.al., 2013). Both are given though in this rapid-fire 4-minute SciShow on what birds see. Video Link : 1752 And what about infrared light? While the human eye can’t see it, our digital cameras can. Turn on your cellphone camera and direct it at the end of your TV remote, the end you point toward your TV. Press and hold the "on" button on your remote. You’ll see the light through your phone’s camera even though your naked eye can't see it. This is also the easiest way to determine whether you need to change the batteries in your remote or whether it's just your dog standing in front of the TV’s receiver. For a short in-class next-day assignment – or same-day assignment, if your students have in-class internet access – or for an online discussion board assignment, invite students to research other individual differences in human sensation or differences in sensory experiences between humans and other animals. In class, students can share in small groups, and then invite volunteers to share the most interesting things they found. Ask students to identify the site where they found the information and why they believe the site is a reputable source.   References Lind, O., Mitkus, M., Olsson, P., & Kelber, A. (2013). Ultraviolet sensitivity and colour vision in raptor foraging. Journal of Experimental Biology, 216(19), 3764-3764. doi:10.1242/jeb.096123 Wagner, K., & Dobkins, K. R. (2011). Synaesthetic associations decrease during infancy. Psychological Science, 22(8), 1067-1072. doi:10.1177/0956797611416250 Wolchover, N. (2012, June 26). How do dogs see the world? Retrieved from http://www.livescience.com/34029-dog-color-vision.html ... View more

Originally posted on April 25, 2014. We’ve all experienced it. You’re some place where screaming isn’t tolerated, some kids starts wailing, and the parents rush to quiet them down. What happens next is the twist: “They’re the best behaved kids we know,” the parents say, as their child continues to bellow. We nod our heads, feign a smile, and go back to what we’re doing. Before you pounce on me for being impatient and inexperienced, I’m here to share some good news. The more positively we view our close relationship partners, the stronger relationship we have. The best part is that the positivity doesn’t have to exist. If you ask many people, they’ll tell you their close friends are above average on nearly every positive trait. They’re funnier, smarter, and kinder than their peers. We might have positive illusions, but that doesn’t hurt anything. Or does it? Let’s return to how we see our kids. Seeing them as above average might have certain benefits. It might boost your parenting commitment and satisfaction. Who wants to devote the time and energy it takes to parent if you see your kid as a dud? A recent study suggests a potential drawback: many parents perceive their children as healthier than they actually are. The study, which drew on several investigations involving over 15,000 children, found that half of parents who have overweight or obese children rate their child as slimmer than their weight suggests. Just as people villainize parents of screaming children, it’s easy to attack parents who don’t know their children are overweight or obese. But let’s show parents some empathy. Parenting is hard. I don’t have kids, but I can’t tell you how much respect I have for people who do. Parents might not want to hurt their children’s feelings by calling them overweight or obese. They also might not know what it means to be overweight or obese. Is it simply if your son fits into his clothes? If your daughter comes home crying because a school bully called her fat? But there’s a third possibility: when we love someone, we see them in the best possible light. Instead of seeing an obese child, we see our daughter who jumps down the stairs to welcome us home from work. We see our son who loves to get dirty in the mud. When I read about the study, I tucked it away in my files. The next morning my wife and I took our two golden retrievers, Finnegan and Atticus, to the veterinarian. They’re both of our dogs, but Finnegan is mine and Atticus is my wife’s. They weighed Finnegan, who came in at a beefy 85 pounds. Then it was Atticus’s turn. “He’s much skinnier than Finnegan,” my wife, Alice, said. “Just look at him.” I looked and realized we weren’t seeing the same dog. “He looks the same to me. We feed him the same amount and give him the same amount of exercise.” “Nah, I bet he’s 70 pounds,” she said. They took Atticus away, weighed him, and returned with the results. He was exactly the same as Finnegan: 85 pounds. So, this finding might apply to dog owners, too. ... View more

Originally posted on February 5, 2015. Even though the smartphone has only been around for the past seven or eight years, it’s sometimes difficult to remember what life was like before we had so much information at our fingertips. You could argue with a friend about what year “Back to the Future, Part 2” came out, or in what year the “future” was set. (It was released in 1989. The future, filled with flying cars and floating skateboards, was set in 2015.) Back then, you couldn’t resolve discussions by swiping a screen and touching a button. Siri wasn’t even a twinkle in Steve Jobs’s eye. If you got lost, you had to consult a map or stop and ask for directions, and if you got bored while waiting in line, you couldn’t pass the time by playing Candy Crush or perusing Instagram. Luddites argue that life was better before the smart phone, whereas others tout the benefits of instant communication and information. But one thing is certain: The smartphone has changed our lives. And our thumbs. Yes, when we spend time on smartphones using a touchscreen, it changes the way our thumbs and brains work together, according to a new study by researchers from the University of Zurich and ETH Zurich in Switzerland. Our obsession with smartphones presented the perfect opportunity to explore the everyday plasticity of our brains. With smartphones, we are using our fingertips—especially our thumbs—in a new way, and we do it a lot. And because our phones keep track of how we use them, they carry a wealth of information that can be studied. In the study, the research team used electroencephalography (EEG) to record brain response to the touch of the thumb, index finger, and middle fingerprints of touchscreen phone users compared to people who still use flip phones or other old-school devices. They found that the electrical activity in the brains of smartphone users was enhanced when all three fingertips were touched. The amount of activity in the brain’s cortex associated with the thumb and index fingertips was directly proportional to the amount of phone use. Repetitive movements over the touchscreen surface might reshape sensory processing from the hand. Cortical sensory processing in our brains is constantly shaped by personal digital technology. So, the next time you use your thumbs to tweet, answer email, or jot yourself a note, remember that you’re training your brain. Keep in mind, too, that excessive phone usage is linked with motor dysfunction and pain. Remember the so-called “BlackBerry thumb”? ... View more