Face perception
April 29, 2008
Category: Face perception • Memory • Research • Social
Humans are exceptionally good at recognizing faces they've seen before. It doesn't take much study to accurately recall whether or not you've seen a particular face. However, this pattern breaks down when faces come from unfamiliar races. A white person who lives primarily among other whites will have more difficulty recognizing Asian faces, and vice versa.
But how engrained is this difference? How much experience with other-race faces do we need to have before we can recognize them as well as same-race faces? Is learning to recognize other races as difficult as recognizing any new category of objects -- cars, say, or birds? When we do learn to recognize other-race faces, do we really know them as well as more familiar races?
While it has been known for some time that we can learn to recognize other race faces as well as our own, this last question hasn't been studied as thoroughly. Maybe in more difficult tests of recognition, we wouldn't do as well with different-race faces.
To explore this question, a team led by Elinor McKone developed a clever set of three experiments. In the first experiment, white Australian students were exposed to 32 different faces -- some white, and some Asian -- for three seconds each. After a brief break where they were distracted with multiplication problems, they were tested on a set of 64 pictures -- 32 they had seen before, and 32 new pictures. Their job was to say which were old and which were new. As expected, the students were significantly more accurate with same-race faces compared to different-race faces. This showed that with brief exposure, different-race faces aren't recognized as well as same-race faces.
Read on »
Posted by Dave Munger at 3:17 PM • Comments (15)
March 28, 2008
Category: Face perception • Memory • Research
[This post was originally published in November of 2006]
Do you recognize the person depicted in this video? (QuickTime required; the movie is below the fold)
Read on »
Posted by Dave Munger at 7:30 AM • Comments (10)
March 25, 2008
Category: Face perception • Perception • Research
Do you recognize the faces in this picture?
Sure you do -- you could recognize the authors of this blog anywhere, even upside-down. It might take you just a bit longer to realize that something isn't quite right with the picture. I'll show you what the problem is at the end of this post.
We've known for decades that the human perceptual system is especially good at recognizing faces, but that ability breaks down in predictable ways when the faces are upside-down. While it takes us a bit longer to recognize objects when they are inverted, faces take even longer compared to other things.
For example, you might be able to tell whether two faces are identical or slightly different when they are upside down, but you'll be quicker to note a similar difference in, say, two houses. When people try to recognize inverted faces, different brain regions are activated compared to recognizing upright faces, but nonface objects activate the same regions whether upside-down or right side up.
But maybe faces aren't the only objects that are special in this way. A team led by Catherine Reed showed observers pairs of pictures of human figures like the one below.
Read on »
Posted by Dave Munger at 8:13 AM • Comments (10)
March 11, 2008
Category: Attention • Face perception • Research
It shouldn't take you long to notice what's wrong with this picture:
Obviously Nora is defying gravity in this shot -- you can't help but notice it. But in your first glance at the photo, how quickly do you notice what's wrong? Do you spot the oddity faster than you'd notice Nora in the original, unaltered picture?
A 1978 study by Geoffrey Loftus and Norman Mackworth found that people respond quicker to unusual or inappropriate objects in line drawings, such as an octopus instead of a tractor in a farm scene. They moved their eyes an average of 7 degrees to fixate on the unusual objects. But in 1999, a team led by John Henderson found the opposite -- people spotted a microscope in a bar scene no sooner than a cocktail glass in the same location, and only moved an average of 3 degrees from where they had been looking previously.
Why the discrepancy? It's hard to know: Maybe, for example, Henderson's team's drawings were just too complicated for viewers to spot differences easily. Or perhaps a microscope in a bar is less unusual than an octopus on a farm. How can we ever measure what's "more unusual" in a given context?
Read on »
Posted by Dave Munger at 2:12 PM • Comments (10)
March 10, 2008
Category: Development / Aging • Face perception • Research • Social
What makes children so cute? Is it their adorably soft skin? Their innocently mischievous smiles? Their oversized eyes and tiny little mouths? Why is it that some kids are singled out for TV commercials and child beauty pageants, while others don't seem to be noteworthy in any way?
Attractiveness in children isn't trivial -- teachers believe more attractive students are more intelligent, and are less likely to punish them for misbehavior. There are also gender differences: Teachers give better grades to attractive girls, but worse grades to attractive boys.
Most studies about cuteness have focused on photographs of children. For example, in the grading study I mentioned above, photos of attractive and unattractive kids were included with essays to be graded by teachers. But when a Japanese team led by Reiko Koyama asked 38 volunteers to tell them what made a child cute, many of the responses were focused on actions: When a child shares with a friend, or imitates adult behavior, or hides in shame, all these things are seen as cute. Out of 148 different examples of cuteness, the researchers selected the 29 most reliable factors, which they divided into four categories: Childlike behavior, physical cuteness, imitating adults, or invoking protective feeling in others.
Read on »
Posted by Dave Munger at 3:25 PM • Comments (4)
February 26, 2008
Category: Face perception • Research • Social
It's hard to resist flirting with babies. Even if a baby has been screaming her head off for hours on end in the seat behind you on a transatlantic flight, if she giggles and smiles when you're deplaning, you'll probably smile back. What is it about babies that makes our hearts melt almost instantaneously when we see them? Is it their cuteness, their happiness, or just their babyness?
A team led by Morten Kringelbach showed photos of babies and adults to twelve volunteers while their brains were being scanned with a MEG (magnetoencephalography) scanner. The key to the study was the control of the photos. Ninety-five judges had previously rated these pictures for the emotion they displayed and the attractiveness of the faces. Both the adult photos and the baby photos were rejected if they were rated as too attractive or unattractive: only middling pictures were chosen for use in the study. Each of the individuals -- 13 adults and 13 babies -- was depicted with a happy, sad, and neutral expression, and again all these photos were selected to have equivalent levels of emotional expression, so the viewers each saw 78 different pictures.
The MEG scanner, unlike fMRI, measures actual neuronal activity, and it responds extremely rapidly, allowing precise measurements within milliseconds after the cells in brain are activated. Viewers were told to look at a small red cross on the screen and press a button when it changed from red to green. They were told to ignore the pictures, which were flashed for about a third of a second between appearances of red/green cross. Of course the researchers were actually interested in the brain activity while the pictures were seen, and they ignored the data from when the cross actually changed color, which happened about 15 percent of the time. Here's what they were really interested in:
Read on »
Posted by Dave Munger at 8:00 PM • Comments (11)
February 25, 2008
Category: Development / Aging • Face perception • Research
When adults are asked if they remember pictures of faces, they're more accurate when the faces are the same race as they are. It makes some sense -- people are likely to spend more time with and have more same-race friends, so they may become better attuned to the differences in individuals in their own racial group. This finding can be especially important in eyewitness testimony: If a crime victim identifies his assailant as someone of a different race, then the research suggests that this identification is more likely to be problematic than an identification of a same-race suspect.
But what about kids? Younger children have less experience, so maybe they don't show the same bias in their ability to recognize different-race faces. While some studies have shown the same pattern in children as adults, an intriguing 1982 study led by J. Chance actually found that there was less of a bias in young children than in older children. Could it be that the bias is actually acquired over the course of childhood?
B. Corenblum and Christian Meissner felt the matter deserved more study, especially because they had identified some problems with the Chance team's study. In that study, kids were shown photos clipped from college yearbooks. Later the kids saw those same pictures mixed in with previously unseen photos, and were asked which pictures they had seen before. It could be that the kids were recalling clothing items or artifacts in the pictures instead of the actual facial features.
Read on »
Posted by Dave Munger at 3:44 PM • Comments (13)
December 19, 2007
Category: Face perception • Research • Taste
Do smells have an impact on how we judge people? Certainly if someone smells bad, we may have a negative impression of the person. But what if the smell is so subtle we don't consciously notice it? Research results have been mixed, with some studies actually reporting that we like people more when in the presence of undetectable amounts of bad-smelling stuff. How could that be?
A team led by Wen Li believes that the judges might have actually been able to detect the odor, and then accounted for it in their response -- giving a face the benefit of the doubt when there's a hint of bad odor.
But odor detection is a tricky thing. Sometimes you're not sure if your milk or wine has gone bad, even after giving it a good whiff. The researchers felt that controlling the odors for a study would be the key to getting good results.
They first determined the odor detection threshold for each of 39 student volunteers. This was done by having each person sniff bottles containing progressively stronger solutions of three different compounds: Citral ("lemon"), anisole ("ethereal"), and valeric acid ("sweat"). The threshold was determined by when they could detect the odor. Then, for the actual experiment, bottles that were about 100 times more dilute were used.
Read on »
Posted by Dave Munger at 5:00 PM • Comments (1)
December 17, 2007
Category: Emotion • Face perception • Research
This past weekend, I went to two different holiday parties. While many of the people at the parties were friends, I was also introduced to a couple dozen new people -- out of town guests of the hosts, friends of friends, or people from our small town that I somehow had never met. If I run into one of these people at the coffee shop tomorrow, how likely will I be to remember that I've met them before? One possibly relevant factor is that I was a designated driver at just one of the two parties.
There's another factor that has been demonstrated to have a significant effect on whether a face is remembered: the facial expression. In 2004, Arnaud D'Argembeau and Martial Van der Linden found that people who viewed a series of photos of faces were more likely to remember smiling faces compared to angry faces -- even when the faces they were later asked to recall had neutral expressions.
In a new study, they wanted to explore the other factors affecting our our ability to remember faces. This time they had 72 volunteers rate 16 faces on one of three different attributes: emotion expressed, intelligence, and nose size. The faces were seen for just five seconds each. Some of the faces they saw were happy, and some were angry. After a one-minute distraction task, there was a surprise memory test. The viewers were shown neutral faces, some of which they had seen before, and some they hadn't. So which faces did they remember? Here are the results:
Read on »
Posted by Dave Munger at 3:58 PM • Comments (10)
December 6, 2007
Category: Attention • Face perception • Language • Movement and exercise • Research
When we are trying to understand what someone is saying, we rely a lot on the movement of their face. We pay attention to how their faces move, and that informs our understanding of what is said. The classic example of this is the McGurk effect, where the same sound accompanied by different facial movements gets interpreted differently.
Take a look at this short video clip (QuickTime required) of me talking, with my voice muffled by what sounds like cocktail party conversation:
Can you understand what I'm saying? What about after I stop moving? Can you understand me in the second part of that clip? Go ahead and replay the video to see if you can hear it the second time through.
That's right, I said two three-word phrases, not just one. If you're like me, you only heard background noise during the second part of the clip. In fact, I'm curious as to whether anyone can understand me at all. Let's make this one a poll:
Read on »
Posted by Dave Munger at 2:08 PM • Comments (27)
November 27, 2007
Category: Emotion • Face perception • Research
Do people ever tell you to "just smile, you'll feel better"? If you're like our daughter Nora, you hear it a lot, and you get annoyed every time you hear it. Telling a teenager to smile is probably one of the best ways to ensure she won't smile for the next several hours. But the notion that "smiling will make you feel better" has actually been confirmed by research. There are several studies demonstrating that people are happier when they smile, at least in certain circumstances.
It's not as easy as you might think to study the effect. For one thing, it's possible that it's not the physical smile itself, but the request that's causing the emotional change. Researchers have attempted to get around that problem by simply directing people to move their facial muscles in a proscribed sequence ("Move your lips to expose your teeth while keeping your mouth closed." "Now use your cheek muscles to pull the corners of your lips outward," and so on). But still, it's likely that research participants will catch on to the purpose of the study when they are asked whether they are feeling happy or sad.
In 1988 a team led by Fritz Strack came up with a brilliant cover story that allowed them to manipulate facial expressions without the research participants' awareness. The researchers told participants that they were studying adaptations for people who had lost the use of their hands. Such individuals would need to use their mouths to hold pencils for writing, or to use a television remote. The study was to assess whether the unpleasantness or difficult of these tasks affected their "attentional abilities and responsiveness." The current study on people with full use of their hands was simply designed to test the procedure.
The participants then held a pencil in their teeth (which naturally activates the muscles typically used for smiling) or lips (which does not activate those muscles), and then rated several cartoons for funniness. Those who were (unknowingly) "smiling" rated the cartoons as funnier than people who weren't smiling.
Innovative as it was, the Strack team's study had several limitations, the most important of which is that the researchers didn't account for the physical differences in holding a pencil with lips versus teeth. If the people are simply more uncomfortable holding a pencil in their lips, that might explain the entire difference between the "smiling" and "not smiling" conditions.
Read on »
Posted by Dave Munger at 3:03 PM • Comments (14)
August 15, 2007
Category: Emotion • Face perception • Perception • Research • Social
On our recent trip to Europe, we had a hard time getting the kids to smile for pictures. Most of our pictures of Nora ended up looking something like this (actually this one's a self portrait, but you get the idea):
Here her expression is basically neutral, and if it wasn't such a dramatic shot, it would be a bit boring.
When we could get her to smile, often the smile was inauthentic -- posed, or even sarcastic, like in this shot:
Here she's expressing mock excitement over her parents' excitement about the figure depicted in the statue: Leonardo Fibonacci, the great mathematician (click on the photo for a closer view).
Authentic smiles generally came at inopportune moments for photography, such as this one:
Read on »
Posted by Dave Munger at 1:48 PM • Comments (9)
July 9, 2007
Category: Face perception • Research • Social
This is a guest post by Christy Tucker, one of Greta's top student writers from Spring of 2007.
Take a look at the following paintings. How alike are they? How can you tell--which clues help you determine similarity? Now, which of these girls are related? If only two of these young girls are related, how would you determine which two? Would they be the same ones that you thought looked very similar?
Laurence Maloney and Maria Dal Martello studied observer's ratings of the similarity between two children's faces in relation to judgments on whether the two are siblings. Do we simply note similarity when trying to figure out siblings? Or do we use a different process? Pairs of pictures of children with neutral facial expressions like the one below were shown to two groups of observers.
Read on »
Posted by Aaron Couch at 9:53 AM • Comments (4)
June 25, 2007
Category: Development / Aging • Face perception • Research • Social
This is a guest post by Rivka Ihejirika, one of Greta's top student writers for Spring 2007
Do you find it harder to recognize the face of someone from a race other than your own? Does it take you longer to recall the face of someone from an unfamiliar race? Some researchers believe that we are born with a predisposition to process faces of those from our own race better than faces from other races. Other researchers believe that the own-race face bias is not innate, but we develop a preference for the race of those in our immediate environment. People of all ages demonstrate the bias to prefer the face of someone from the same race. Yair Bar-Haim and his colleagues wanted to find how much of this own-race face bias was due to nature and how much was due to nurture.
Read on »
Posted by Aaron Couch at 9:53 AM • Comments (14)
May 8, 2007
Category: Development / Aging • Emotion • Face perception • Intentionality • Research
Take a look at these two pictures. Who is more dangerous?
It's not hard to decide, although I wouldn't hurt a fly, and Nora, even at age three, could be brutal with her sarcasm. Now, what's the most dangerous situation?
Again, an easy decision. While Carhenge is certainly an awe-inspiring monument (and perhaps Jim could scratch himself on one of those cars), Nora's descent of this rock spire gives me shivers.
You might think that there aren't many differences in how adults judge threats in examples such as this, but there is some reason to believe that older adults may have a different response to danger than young adults. The volume of the amygdala, the so-called center of fear in the brain, decreases with age. The frontal cortex, believed to be the area responsible for understanding the thoughts and intentions of others, also diminishes in size more rapidly with age compared to other parts of the brain.
Ted Ruffman, Susan Sullivan, and Nigel Edge showed pictures like the ones above to both college students (younger adults) and older adults averaging age 69. Each picture was rated on a scale of -3 (not dangerous) to +3 (dangerous). Some of the pictures were faces, and some depicted situations like extreme sports, wild animals, or weather events, with no visible human faces. All these pictures had previously been categorized by both younger and older adults into low danger, medium danger, and high danger categories. Here are their results:
For the situation pictures, the difference between young and old adults was not significant, but for faces, older adults consistently rated the threat from the high danger pictures significantly lower than younger adults. The same pattern occurred whether the pictures had been previously categorized by younger or older adults.
This difference can't be explained by the strategy used to rate the pictures: both young and old adults tended to rate pictures of women and smiling faces as less dangerous.
The researchers make a compelling, though not conclusive case that what may be going on here is that older adults are simply worse at determining threats from faces than younger adults. After all, the results held true whether the categories had been determined by old or young people. Yet it's still possible that young adults are the ones who are consistently wrong.
If the differences in young adults and older adults really are due to some sort of decline in ability, then Ruffman's team suggests that future research might focus on imaging the brain while participants rate this set of images: if differences in ratings correspond to differing brain activity, that would also suggest that older adults' system for assessing threats has been compromised.
Ruffman, T., Sullivan, S., & Edge, N. (2006). Differences in the way older and younger adults rate threat in faces but not situations. Journal of Gerontology: Psychological Sciences, 61B(4), 187-194.
Posted by Dave Munger at 2:25 PM • Comments (17)
April 26, 2007
Category: Face perception • Language • Movement and exercise • Research • Social • Video Games / Technology
There is a considerable body of research showing that eye contact is a key component of social interaction. Not only are people more aroused when they are looked at directly, but if you consistently look at the person you speak to, you will have much more social influence over that person than you would if you averted your gaze.
The problem arises when you address a group of people. How do you pick who to engage visually? Most public speakers are encouraged to look around the room, alternating eye contact with individuals in the audience. But there's no way to look at everyone at once -- so some of your potential social influence will by necessity be lost.
Now, a team led by Jeremy Bailenson has figured out a way to get around that limitation. In a virtual reality environment, there is no need for the representations of other people to be consistent. Since each individual's virtual experience is generated separately, in a "room" full of people, each person could experience the phenomenon of everyone else looking at them. Everyone can be the center of attention, all at the same time!
In the figure, person A believes that both B and C are looking at her. But in C's virtual world, both A and B could be shown as looking at her instead.
Bailenson's team wanted to see if they could use this method to allow one person to increase his or her influence over more than one other person simultaneously, by programming her "avatar" -- the virtual representation of herself -- to be looking directly at each of the others.
Read on »
Posted by Dave Munger at 2:45 PM • Comments (21)
Cognitive Daily reports nearly every day on fascinating peer-reviewed developments in cognition from the most respected scientists in the field.
