Perception
dmunger | November 29, 2006One of the unanswered questions in Krista Hyde and Isabelle Peretz's research on amusia ("tone-deafness") is why amusics frequently say they are unable to clap to the rhythm of a song, or to dance well. In Hyde and Peretz's study, amusics could detect rhythm changes as well as normal individuals, even while being unable to detect changes in musical pitch.
Hyde and Peretz speculated that amusics might not be able to detect rhythm changes when the pitch of the notes change -- that their problems with rhythm might be directly related to the fact that amusics can't detect many changes in pitch.…
dmunger | November 7, 2006Take a look at this video of a professional drummer playing the conga:
It's easy to see that the sound coming from the drum is perfectly synchronized with the motion of the drummer's hands. Or is it? When a sound enters your ear, it takes less than 1 millisecond for the signal to be transported from the outer to the inner ear, where it can be perceived by the brain. The equivalent process in the eye takes 50 milliseconds. Then there is the matter of the physical difference in the speed of light versus sound. If the drummer is between 15 and 20 meters away, the faster travel of the light…
dmunger | October 23, 2006There's nothing cooler for a perception researcher (or writer) than a new visual illusion. When I learned about this one, I spent half the day Thursday trying to recreate it, but I couldn't get it to work. Finally, in five minutes on Friday morning, I think I figured it out. (Update: Actually, as it turned out, I didn't figure it out at all. In the meantime, Chris from Mixing Memory pointed me to Shams' web page with much better demos. So let's try this again, using one of Shams' demos.) Play the movie and watch for a dot flashing in the middle of the screen. Make sure you've got the sound…
dmunger | September 29, 2006Occasionally you read a journal article so well-titled, you have to steal it for your blog post title. "Smells Like Clean Spirit" is a report by Rob Holland, Merel Hendricks, and Henk Aarts, in which they use smells to unconsciously modify their victims' participants' behavior.
In some ways, this research is nothing new. As the researchers point out, if we smell chocolate chip cookies, we may decide to eat; if we smell a garbage truck, we may walk faster down the street. We might associate pine scent with Christmas, or pheromones with sex. But most of these associations involve people being…
dmunger | September 14, 2006Color categories, as we pointed out in this post, are remarkably consistent, even across different cultures and languages. "TLTB" pointed out in the comments that for people with color blindness, the color categories might not make much sense. He brought up an excellent point, one that becomes doubly perplexing when we realize that no two individual eyes are the same -- indeed, retinal scanning is considered more accurate than fingerprints in establishing someone's true identity.
The distribution of cones and rods across the retina varies substantially. What's more, the macula, a region in…
dmunger | September 6, 2006Sometimes we think of emotions as completely separate from the more "objective" parts of the mind. You might believe that emotion can sometimes cloud your judgment, but it certainly can't affect your vision system. Or can it?
Take a look at the following image. It's my attempt to use Photoshop to make a Gabor patch -- a means of testing vision.
Gabor patches are useful because researchers can systematically vary their contrast and determine the limits of the visual system. For example, try this quick movie. The screen will remain blank for a second, then quickly flash four Gabor patches.…
dmunger | August 24, 2006
Last year, my dad got his pilot's license. He took me up with him a couple months later, and while the view was spectacular, the most surprising aspect of flying is how much of a pilot's time is spent avoiding other aircraft. You might think there's plenty of room up there, and you'd be right, but it also means you have to scan a vast space to locate other planes. Once you spot one, you need to keep track of it to make sure you're not on a collision course. Sometimes, you'll need to track four or more other planes. Is there a limit to how many objects we can track? And how, exactly, do we…
dmunger | August 22, 2006 Learning to navigate through an unfamiliar environment can be a difficult challenge. Could you find your way through the crowded, narrow streets of the city depicted at left -- especially if the signs were in a foreign language (bonus points if you can identify the city in the comments section!)?
If you do have to get around in a new place, what's the best way to learn? People have different preferences -- some prefer to look at a map first, while others orient themselves using landmarks. Is one method better for you? I prefer maps; nothing's more frustrating to me than getting directions…
dmunger | August 17, 2006By the time a baby is 4 months old, she has begun to amass an impressive array of skills. She might be able to roll over, as Nora is demonstrating in this picture. She will almost certainly be able to follow an object with her eyes as it moves across her field of vision. But research about the ability of babies to follow objects has had conflicting results. In some cases, babies this age seem to understand that when one object passes out of view behind another, it's still "there," just hidden from view.
Consider a simple example: a single ball moves back and forth behind a rectangular box,…
dmunger | August 11, 2006What in the world is this thing?
It's called an optokinetic drum, and it's one of the many implements of torture you'll find in a spatial orientation lab. In an optokinetic drum, you sit or stand inside while the entire drum rotates around you. By changing the pattern on the inside of the drum, or by changing the way the drum rotates, a researcher can easily make you lose your lunch, breakfast, or even last night's dinner.
I got the picture of the drum from the Ashton Graybill Spatial Orientation Lab, where you'll find plenty of other devices that I sincerely hope the U.S. military doesn't…
dmunger | August 8, 2006Take a look at this short video clip. Can you tell which dot is blue and which is yellow?
Click here to play
Unless you have a rare vision impairment, this task should be easy for you. But read on, and we'll show you how you can become blind to this difference in as little as 40 minutes.
The human visual system is amazingly adaptive to eye movements. Consider this: if you film a video from a moving car, the resulting image is so jiggly that it's unwatchable. But if you're riding in the car, even on a bumpy road, the outside world appears stable and smooth.
Or take a camcorder and move it…
dmunger | July 31, 2006[originally posted on March 16, 2005]
I'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…
dmunger | July 20, 2006[article originally posted September 27, 2005]
All this talk about stereotypes can get you thinking. Perhaps some stereotypes reflect actual differences. Take color vision, for example: men often refer to themselves as "color-impaired," letting the women in their lives make home design decisions and even asking them to match clothing for them. Maybe they're just behaving in accordance with traditional stereotypes ... but maybe there's something more to it.
In the 1980s, vision researchers began to find some real physical differences between the eyes of many women and those of most men. "…
dmunger | July 5, 2006"Keep your eye on the ball" is a mantra I've heard applied to several sports: baseball, for hitting, football, for receiving, and golf, for teeing it up. It wasn't surprising to me when I read recently that cricketers also use this platitude to teach batsmen how to hit effectively.
The sum total of my experience with cricket is watching multi-ethic games in Van Cortland Park through our Bronx apartment window while Greta and I were finishing graduate school about 12 years ago. I didn't pick up on many of the rules, but I was stunned to see that cricketers, unlike baseball players, actually…
dmunger | June 28, 2006When I play video games with my son Jim, I'm generally at a tremendous disadvantage. Most of the time, Jim has had more experience with the particular game we're playing, but even when we try a brand-new game, he just seems to get his bearings more quickly than I do. He doesn't have more experience with games or computers than me -- I played just as many games as he did when I was his age, and I've had an extra 25 years to hone my skills.
At age 39, I don't consider myself "old," and since I work with computers for 8 or more hours a day, I'm certainly not intimidated by the games or the…
dmunger | June 26, 2006Developmental psychologists since Piaget have been interested in how well children are able to take the perspective of another. Piaget's laboratory had a large table with elaborate models on top; children who were able to take the perspective of a doll on the table and explain what the table looked like from her perspective instead of their own perspective were said to be at a later developmental stage.
But understanding whether a doll can "see" something doesn't always literally require taking her perspective. Take a look at this simple arrangement of objects on a table:
You don't have to…
dmunger | June 12, 2006Experiments on change blindness have revealed striking limitations in visual memory. Take a look at the video below, for example (click to play -- and note that the video is contained in a java applet that may take a while to load -- but it's worth it!).
The woman is giving directions to one "construction worker," when two other "workers" carry a door in between them. A new worker (all of them are actually actors hired by the experimenters) is substituted during the hubbub, and the woman continues giving directions as if no change has occurred. This work has been duplicated in a variety of…
dmunger | June 5, 2006I've been an avid skier for over 25 years -- but I didn't start using goggles until very recently. Under the overcast Washington State skies, they didn't seem to be necessary. But now that I live in North Carolina, skiing is usually done under sunny skies on artificial snow; goggles are a must. As a person who also wears glasses, however, the experience can be frustrating -- any time I stop for more than a few seconds, my goggles, glasses, or both will usually fog up -- the goggles rely on airflow to keep from getting foggy. In this situation, I'm left with two choices: proceed with impaired…
dmunger | May 26, 2006Take a look at the following movie. Your job is to identify which ball appeared to make the noise in the final frame. (click to play):
If this seems confusing now, it should be cleared up by the end of this post. You can register your result in this poll:
Synesthesia, as we've discussed before, is a rare condition. Synesthetes are people who perceive stimuli presented in one mode (often corresponding to one of the five senses) with a different mode. It's a remarkable ability, manifesting itself in a variety of different ways -- seeing "auras" around friends, or associating a sound or even…
dmunger | May 16, 2006The text below will bring up an animation. Just look at it once -- no cheating! A picture will flash for about a quarter of a second, followed by a color pattern for a quarter second. Then the screen will go blank for about one second, and four objects will appear. Use the poll below to indicate which object (#1, 2, 3, or 4) appeared in the picture.
Click here to view the animation!
I'll let you know which answer was correct at the end of the post, but this test approximates the procedure of an experiment conducted by Kristine Liu and Yuhong Jiang, designed to measure the capacity of visual…