Perception
dmunger | May 3, 2005When we were first married, Greta and I lived in New York City for five years. One of the biggest challenges of living in New York was navigating around the subway stations, complex warrens of underground tunnels that can extend for hundreds of yards. I was certain I had the best method for figuring out where to go: try to keep a mental map of the entire station in my head, not relying so much on local landmarks as the "big picture." Greta was equally convinced that her way was best—look for local landmarks, signs, and other clues for where to go. Instead of remembering a "map," she…
dmunger | April 30, 2005We often think of music as expressing emotions, and research has backed this notion up. But typically the research has focused on melodic instruments: sweet, sorrowful violins; bright, happy guitars; melancholy, wailing oboes. So what about percussion instruments: drums, cymbals, tympani—can they express emotion too?
Listen to the following short music clips. As you listen, try to determine what emotion they are expressing. Think of it as a multiple choice test. You get to choose between solemn, tender, fearful, angry, sad, or happy.
clip 1clip 2clip 3clip 4
Source: courtesy of Travis Lloyd…
dmunger | April 25, 2005It's impossible to pay attention to everything in the visual field at once. If we could, magicians would be out of business: most "magic" tricks work by distracting the viewers' attention while the real trick is being done in plain sight.
However, if a new object enters our field of view, we quickly direct our attention that way and make note of it. This would have come in handy for our ancestors as they kept watch for predators. Now its primary use is probably avoiding car accidents (or shutting down Web browsers when the boss shows up at your cubicle!). Interestingly, this facility is not…
dmunger | April 9, 2005
(source of original images: Wikipedia. See license)
When my daughter Nora was 15 months old, she had started to pick up a few words. She could say "Mommy," and "Daddy," and "JimmyNO," which is what she called her brother. However, she had only two words for animals: all animals were called either "duck" or "dog." Animals with two legs were ducks, and animals with four legs were dogs. This worked fine, even when her grandparents took her to the zoo. The warthog was a "dog," and so was the giraffe and the zebra. Peacocks, pigeons, and kangaroos were all "ducks" to Nora. The only difficulty…
dmunger | April 6, 2005Listen to these two musical excerpts and note any differences you discern:
Ave Maria, version 1Ave Maria, version 2
(Source: courtesy of Mayumi Hamamoto and Kyota Ko)
If you're a typical nonmusician, you will probably notice some sort of difference between the two excerpts. Maybe one seems to be played at a different tempo, or with different instrumentation, or is a bit longer or shorter. You probably won't think either clip sounds unpleasant, and you might not notice any differences at all.
If you are a professional musician, on the other hand, you may find the second clip so appalling that…
dmunger | April 5, 2005It is well known that humans and other animals can recognize biological motion when shown only a point-light display. Other research has shown that social cues are deeply embedded in our perceptual system. We can also perceive emotions and intentions in simple geometric displays.
So what is going on in our brains while we watch such displays? A team of researchers led by Johannes Schultz found some answers (Johannes Shultz, Hiroshi Imamizu, Mitsuo Kawato, and Chris Frith, "Activation of the Human Superior Temporal Gyrus during Observation of Goal Attribution by Intentional Objects," Journal…
dmunger | April 4, 2005Wine expert Robert Parker claims to be able to distinguish every wine he has ever tasted—10,000 different wines a year—by taste alone. Winemakers can use their sense of smell to detect slight imbalances early in the wine production process that might lead to a spoiled batch. Meanwhile, novices walk the aisles of the typical wine store in a daze, uncertain of which wine to select and unsure whether paying a premium for a "better" vintage is worth the cost. During the German occupation of France, when winemakers were forced to ship their best wines to Hitler's henchmen in Berlin, they poured…
dmunger | March 30, 2005Psychologists and neuroscientists can be said to be working on the same problem, but they tend to approach it from opposite directions. Psychologists generally look at behavior and then try to understand the mental processes that might cause that behavior. Neuroscientists look at brain activity and see how it corresponds to behavior. Then people who are considerably smarter than me try to synthesize the work of both psychologists and neuroscientists in order to come to a complete understanding of how we think and behave.
One piece to add this puzzle is a recent study by Kevin Pelphrey, James…
dmunger | March 28, 2005The NCAA basketball tournament is down to the wire now, with only four teams left. How will the players respond? Will they be able to perform under the incredible pressure from the other teams, the coaches, and most of all, the fans filling in their tournament pool brackets?
Today's headline might be just a tad misleading. While psychologists may not be able to predict the results of the games, they are beginning to develop a better model of what's going on inside highly trained athletes' minds while they play. André Didierjean and Evelyne Marmèche of the Université de Provence just completed…
dmunger | March 24, 2005When we look at a scene, it often seems as if we perceive it all at once. Yet in fact, we are physically able to accurately view only a tiny portion of the scene at a time. Take a look at this image of a human retina (the back of your eyeball). The portion of the eye responsible for accurate vision is the miniscule fovea:
(source: Webvision)
To get a sense of the portion of your visual field you are able to see in clear focus at one time, hold your thumb up at arm's length. The area of the fovea corresponds to the size of your thumbnail at that distance: less than 2 degrees of visual angle!…
dmunger | March 23, 2005When you look at a picture, you are probably generally focused on the central objects, though the overall style might catch your eye. But what about your memory for the background of the picture? Put another way, how accurate are you at recalling the exact borders of a particular view? For that matter, how accurate are you at remembering the borders of the objects depicted in that picture? Carmella Gottesman and Helene Intraub of the University of Delaware were curious about these questions, and so took some special pictures that had objects stacked on objects ("Constraints on spatial…
gmunger | March 21, 2005Have you ever noticed that when you drive by a car whose hazard lights are blinking, something doesn't look quite right? You know those blinking hazard lights are really on the car, but they seem off, somehow. Part of what might be going on is something called the flash-lag effect. Take a look at the movie below, and decide whether or not the blue flashed object is exactly aligned with the end of the gray rod. To start the movie, click on the rod.
In general, it looks as if the blue object is a bit behind the rod; or that the flashed object is lagging relative to the moving rod. This…
dmunger | March 16, 2005I've taken only two pictures of the Mona Lisa, and both turned out about the same: they captured the frenzied attempts of dozens of tourists trying to take a picture of the most-recognized image in the world. Here's the one I took last summer:
I hadn't noticed it until now, but the motion of the painting in the background seems to mirror the chaotic struggle of the tourists with their cameras. I wonder if the Louvre's curators placed it there as a sort of an inside joke.
But this post isn't about museum curators, it's about one feature of the Mona Lisa that's supposed to mark Leonardo as a…
dmunger | March 10, 2005About two weeks ago I engaged in a seemingly pointless exercise in male bonding: I played 24 hours of video games with my son. It turns out, even aside from perfecting my guacamole recipe, the experience may have done me some good.
C. Shawn Green and Daphne Bavelier of the University of Rochester conducted a study in which they found that avid video game players were better at several different visual tasks compared to non-gamers ("Action Video Game Modifies Visual Attention," Nature, 2003).
I'll get to the specific tasks they studied a little later, because I want to focus in on the really…
dmunger | March 8, 2005Have you ever played around with point-light displays? If not, take a few moments to explore the amazing site I've linked. Through these simple animated displays, we can detect gender, emotion, even species. Point-light displays have been studied for decades as a way to understand how we perceive biological motion. Even pigeons, quail, and cats appear to recognize animals when they are shown point-light displays.
You might think the simple fact that other animals can also recognize these displays suggests that perception of biological motion is "hard-wired" into our brains—and it is indeed a…
dmunger | March 2, 2005Take a look at the following movie (quicktime required). The movie will alternately flash a picture of a desk and a patterned block. Your job is to see if anything about the picture of the desk changes each time it flashes. Don't replay the movie when you get to the end; just stop.
Did you notice any changes? Most people won't spot any changes at all when they watch this movie the first time. But watch the image as you press play again, and you'll see that the desk has changed significantly from the beginning to the end of the movie. I actually rotated it by two degrees at each point along…
dmunger | March 1, 2005When you were a child, did you ever bend over and look between your legs to see what the world looked like upside down? If you were like me, you were disappointed: for me, anyways, the world didn't look as different as I had hoped. Though turning things upside down does make it more difficult to get around, we're actually quite good at adapting to changing our head position. You can do an experiment to see just how good you are at it. Fix your eyes on an object ten feet or so away. Now tilt your head to the left and to the right. Does it appear as if the image is tilting back and forth as you…
dmunger | February 28, 2005One of the most famous perceptual demos is the ambiguous image or "bi-stable figure" of a duck - rabbit:
(source: curiouser.co.uk)
As presented, it looks like a duck, but rotated to the right, it suddenly "transforms" into a rabbit. There are also images that can transform simply based on how you look at them. Artists like Eshcher were fascinated by such images, but it was Salvador Dali who took the phenomenon to the next level with paintings like Slave Market with the Disappearing Bust of Voltaire:
(source: Artchive)
It's worth checking out the image on the Artchive site because you can…
dmunger | February 25, 2005Aristotle wrote that drama must be guided by three principles, the Unities. All aspects of a good play must take place in the same location, within a short time period, and contribute to a single plot. Otherwise, forced to stretch their imagination, the audience wouldn't be able to suspend disbelief, and the play would cease to be a reasonable imitation of reality. The ideal play would take place over the same amount of time it took to perform (say, two hours), would be set in the same place, and would have a single course of action.
It is indeed an interesting feat when a play or a film…
dmunger | February 17, 2005Most schools of literary criticism suggest that it's fruitless to attempt to consider what the intentions of the author are; we can only examine the "text" itself: it is the only solid evidence we have. Similarly, critics toss up their hands when trying to comprehend the experience of the reader of a text. While the notion of "author" becomes even more complex when we consider film, examining the experience of the film viewer does seem to be attainable: since films are experienced in real time, we can compare the experiences of different viewers while they watch the same portions of a film.…