Cognitive Daily

We spot faces looking at us faster than we see the parts of those faces

Tue, 02 Dec 2008 16:46:41 -0500

We can quickly spot a face staring at us in a crowd. We can do this much quicker, for example, than we can determine that no one is staring at us, as this movie demonstrates. A grid of 100 pictures of Greta will be flashed for about 1/3 of a second. Can you spot the photos where she's looking at you? You'll see two different grids.

Most people are able to detect the staring faces much faster than those looking to the side. But we can also sometimes be fooled by faces, something we discussed on one of the first-ever CogDaily posts:

In this picture, the eyes for each face are exactly the same, but the face on the right appears to be staring directly at us, while the face on the left seems to be looking off to the viewer's right.

A similar effect can be achieved in reverse, keeping the head position the same while changing the eyes:

Faces 1 and 2 are identical except for the eyes, and face 1 appears to be looking at us while face 2 seems to be looking away. Meanwhile, neither face 3 nor face 4, which use the same eyes as faces 1 and 2, seems to be looking at us. So when the only difference between the faces in a group is a subtle difference in eye position, will we still spot the pictures that seem to be looking at us faster?

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Casual Fridays: When do you stop for pedestrians?

Fri, 28 Nov 2008 16:10:45 -0500

Greta walks a mile to work every day. I work at home, so I don't walk around town much. I'm much more likely to be driving down the street where we live than walking on it.

Does this affect our attitude towards pedestrians when we drive? Greta and I have also both noticed that there are certain situations where drivers seem more likely to stop for pedestrians than others. Is it a universal rule? Or are our own observations biased by our personal experience?

This week's study may give us a way to find out. I've taken several photos of a pedestrian at/approaching a crosswalk. Your job is to imagine you're driving a car and describe how you would react in each situation. Be honest! If you have your own theory about when drivers will and will not respond, be sure to let us know about it in the comments.

Click here to participate

The study has about 20 questions; it should take about 3-5 minutes to complete. You have until Thursday, December 4 to respond. There is no limit on the number of responses.

Don't forget to return next week for the results!

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Implicit attitudes: Are we biased about the foods we buy?

Wed, 26 Nov 2008 14:36:55 -0500

(This entry was originally posted in May, 2006)

We've discussed implicit attitudes on Cognitive Daily before, but never in the context of food. The standard implicit attitude task asks you to identify items belonging to two different categories. Consider the following lists. Use your mouse to click on items which are either pleasant or related to Genetically Modified foods (GM foods). (Clicking won't actually do anything, it's just a way of self-monitoring your progress)

Horrible
Good
Transgenic
Nasty
Crops
Wonderful
dislike
GE livestock

Now with this next list, do the same task, only click on items which are either unpleasant or related to GM foods.

Happy
Bad
GM plants
Likeable
Engineered salmon
Terrible
Modified tomatoes
Excellent

Which task was harder? I'm including a poll below the fold for you to register your results.

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You can create a "false memory" in a fraction of a second

Mon, 24 Nov 2008 17:26:19 -0500

Boundary extension is a phenomenon we've discussed a lot on Cognitive Daily. It's typically described as a memory error: We remember scenes as having bigger boundaries than what we originally saw. Take a look at these two pictures of Jim:

If you only saw picture A by itself, then later you'd remember seeing a picture that looks more like picture B. If you look at them side-by-side, it's easy to see that picture A is cropped closer than picture B, but if you see the pictures separately, then it's likely you'll misremember the first picture has having broader boundaries than it really has. That's boundary extension.

But how quickly does boundary extension occur? Very quickly, as this movie demonstrates:

Here I've separated the two shots of Nora by only 1/2 second. To my eye, they don't look any different -- it's as if I saw the same picture twice. But the second viewing (with no filler image inbetween) shows that I actually extended the boundaries. If this is repeatable, can we honestly now say that boundary extension is a "memory error"? How quickly does boundary extension actually occur?

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Casual Fridays: Does having kids destroy your memory?

Fri, 21 Nov 2008 16:30:21 -0500

Last week we wondered how having kids affects our own childhood memories. In many ways, our kids remind us of our own childhood, allowing us to relive our favorite memories. But kids also distract us by being so adorable (or not so adorable), and with new memories that might become more prominent than the old ones.

My own experience suggests that kids do remind me of my own childhood. Now that Jim and Nora are teenagers I find myself thinking about my own experience in high school -- sometimes about memories I hadn't considered for decades. But maybe that's an illusion. What I would have remembered if I didn't have kids?

This week's Casual Friday study does offer a tentative -- and surprising -- answer. We asked our readers how many of their teachers' names they could remember. We also asked them how many kids they have. This graph shows the relationship between their memory performance and number of kids:

There's actually a slight decline in memory performance as the number of kids in a family increases. That decline is significant: respondents with more kids said they could recall significantly fewer teachers from their own childhood. Whoa! Does having kids destroy your memory?

Maybe not: One obvious explanation for this result is that memory declines with age. Older people are more likely to have kids, and -- it would seem -- less likely to remember their own childhood, whether or not they have kids. Our data bears out some of that reasoning, but not all of it. First, take a look at this:

Our readers do remember significantly fewer of their teachers as they get older. But now let's combine reader age with whether or not they have kids:

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CogDaily's best posts of the year?

Thu, 20 Nov 2008 10:27:01 -0500

Here are the four posts that I selected to nominate for Open Laboratory 2008, the collection of the best science blog posts of the year:

Disagree with my choices? You can nominate one yourself, here. But remember that the post has to work in book form (with some adaptation). I had to pass over some great posts because they included videos or other interactive elements.

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Seeing shapes in two different ways: how and when it happens

Wed, 19 Nov 2008 15:00:01 -0500

A Necker cube is bi-stable figure, meaning that it can be perceived as two different three-dimensional objects, depending on how you look at it:

Cube A is ambiguous -- the true Necker cube. Cube B and cube C show the two ways you can perceive the Necker cube: either the bottom of the cube is in front, or the top is in front. What's interesting about figures such as the Necker cube is that once you're aware of its bi-stable nature, it's impossible to see it only one way. Don't believe me? Then take this challenge. Play the movie below (it lasts for two minutes). The figure will flash every couple of seconds, but otherwise there are no tricks involved -- the identical, ambiguous figure is portrayed the whole time.

You can choose whether you'd like to see it as bottom-in-front (like cube B) or top-in-front (like cube A). But you won't be able to maintain that perception for the entire time you watch. Just make sure you're perceiving it as a cube, and not just a two-dimensional group of lines.

Stop the movie once you see the reverse, and let us know how long you lasted in this poll:

Researchers have found even when they're trying to avoid a reversal, people switch at least once every fifteen seconds. The flashing makes it more difficult to avoid reversing, but even non-flashing objects are always reversed. People who say they never reversed are lying (with one possible exception, which I'll get to later).

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Plunging in to social networking

Mon, 17 Nov 2008 20:27:43 -0500

I've set up accounts on FriendFeed and Twitter with the username davemunger. I'm going to give these sites a try for the next week or so. Unlike with Facebook where we've got a profile but haven't really done much, I'd actually like to actively participate in these networks.

I'd appreciate any tips readers have for getting established there, and any other similar sites that it might be useful to be a part of. Ideally these sites would link back in to FriendFeed so I only have to check up on one site. And of course, if you'd like to follow my feed, you're welcome to.

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Does involving parents really help students learn? Depends on how they're involved

Mon, 17 Nov 2008 13:18:33 -0500

One of things I was taught over and over again when I was in education school was the importance of getting parents involved in kids' learning. If you get the parents on your side, my professors insisted, then you're going to be much more able to get through to the students. I didn't last long enough as a teacher to see how well this advice worked, but as a parent, I've certainly experienced the process from the other end. From an early age, our kids were given "homework" that they couldn't possibly do without the help of their parents.

Sometimes it seemed as if these assignments were really not for the kids at all; they were for the parents to do alone, perhaps with a little "help" from the kids. In first grade, Jim came home with a sheet describing a puppet-making project. Jim wanted to make Barnum Brown, the paleontologist who uncovered the first Tyrannosaurus rex. Jim's idea of "helping" was to draw a picture of the scientist and have Greta craft the puppet based on his drawing. It was a beautiful puppet, but I'm not sure what Jim learned from the experience. I looked through our closet and found that we still have the puppet! Here's a picture of Barnum Brown the puppet, and the man himself:

It's only recently that I've had a chance to look closely at some of the research behind the idea that parents should be involved in their kids' homework. It stems from the idea (promoted by Lev Vygotsky and others) that learning is a social process, and so things learned in more authentic social contexts are processed more effectively than in other environments.

Of course, doing a child's homework for him doesn't exactly constitute an authentic social context. What several studies have confirmed is that work done collaboratively seems to be more effective than work done alone. Kids even misremember their own contributions to a collaborative project: They think they did some of the work that was actually performed by others (but they don't make similar errors and believe that others did their work).

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Casual Fridays: Does having kids enhance or detract from our own childhood memories?

Fri, 14 Nov 2008 13:48:25 -0500

This morning I was having a conversation with Nora about her AP European history class, and it got me thinking about my own experience taking the same class about 25 years ago (yes, kids, they did have AP classes back then). Mainly it reminded me that I can't remember much at all about the class. I remember lots of facts about European history, but I can't track any of them specifically to that class. But it also made me wonder if I would have thought about that class at all if it hadn't been for Nora taking the class now.

On the other hand, I seem to remember my other AP classes from high school better (in case you're not familiar with the US high school curriculum, an AP class is a "college-level" class that's taken during high school), even though Nora hasn't taken any of those classes yet. So maybe some other factor is more important in determining what we remember from our childhood.

We might have an opportunity to find out with a Casual Friday study. We'll ask if you can remember your teachers' names from each grade in school, and then we'll ask a few questions about yourself -- whether you have kids, how old they are, and so on. If enough people respond, we may be able to suss out whether having kids helps or hinders memory.

Click here to participate

You should respond whether or not you have kids -- we need all sorts of respondents in order to compare the results. The study has about 15 questions; it should take about 3-5 minutes to complete. You have until Thursday, November 20 to respond. There is no limit on the number of responses.

Don't forget to return next week for the results!

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Dave and Greta speaking at CLT WordCamp tomorrow

Fri, 14 Nov 2008 11:05:07 -0500

Greta and I will be participating in a panel on blogging tomorrow in Charlotte, NC. If you're in town, you might want to stop by. More information here.

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How, exactly, do sad faces affect our ability to count?

Thu, 13 Nov 2008 15:02:04 -0500

Remember this video?

A few weeks ago we used it to demonstrate that facial expressions can disrupt the perceptual system in fundamental ways. Actually, because we could only show a few short clips, we weren't able to duplicate the research results found by John Eastwood, Daniel Smilek, and Philip Merikle. But in their, more comprehensive study, although viewers were instructed only to count "upturned arcs" or "downturned arcs," when those arcs formed "faces" with negative expressions, people counted the arcs slower and less accurately.

But how exactly do facial expressions disrupt the perceptual system? Is it something automatic and irreversible? Or can we create a situation where facial expression doesn't matter?

A new team, again led by Eastwood, tackled this question with three ingenious experiments. In the first experiment, volunteers were shown dozens of movies like the one above, and again asked to count upturned and downturned arcs. But this time, there was a critical difference. In half the movies, the arcs they were supposed to count were colored red, while the other arcs were gray, like this:

The other movies were just like the example above, with no color difference in the arcs. Did coloring the arcs have an impact? Here are the results:

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Should you let your toddler/preschooler watch TV? Part II

Wed, 12 Nov 2008 16:59:36 -0500

When Jim and Nora were toddlers, they were huge fans of everything Disney. Here they're wearing their Disney pajamas as they play next to their Seven Dwarves figurines, underneath their TV, which was frequently used to watch Disney videos. We even took them to Disney World, where they had an absolute blast, but turned out to be afraid of life-sized Disney characters (but that's a story for another day).

While we didn't let them watch Disney movies whenever they wanted, we did allow it once or twice a week, and even built up a large collection of videos, which we still use to entertain younger guests.

But Disney movies aren't benign. In fact, they're quite violent, and often in ways that can be very disturbing: mothers and fathers are killed, children are abandoned, vicious, brutal battles are fought. As we discussed a couple weeks ago, toddlers who are allowed to watch entertainment shows (as opposed to educational TV, and including violent shows) are significantly more likely to develop attention problems when they're older.

But does violent TV have other impacts? In a separate study, the same researchers -- Dimitri Christakis and Frederick Zimmerman -- took a look at the same 1997 survey results and a 2002 follow up of families with small children (330 kids in all). The kids were age 18 months to 5 years old in 1997. This time in addition to TV-watching, the researchers looked at parents' reports of antisocial behavior of their kids when they were older. The parents rated their kids on a scale of 1 to 3 for six different statements: "My child cheats, is mean to others, feels no regret, is destructive, is disobedient at school, and has trouble with teachers." Based on these responses, they divided the kids into two groups -- those whose antisocial behavior was problematic (corresponding to the 90th percentile of antisocial behavior in the general population), and those who showed normal social behavior.

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Can a blind person whose vision is restored understand what she sees?

Tue, 11 Nov 2008 15:50:15 -0500

Philosophers have wondered for centuries whether someone who was blind from birth would "see" the world in the same way as people with normal vision. After all, there's much more to perceiving the world than properly functioning eyes. Think of it: otherwise all you'd need to do is strap a camcorder to a car and you'd never have to learn how to drive!

But there are surprisingly few cases of people who were born completely blind and then had their sight restored after many years of blindness. If a patient can be cured, it's usually done quite early in life. But a few cases have emerged in recent years, the most promising of which was a woman from India who goes by the initials S.R.D. She was born almost completely blind, able to tell day from night but otherwise unable to perceive anything visually. At the age of 12, she underwent surgery to correct her vision, which was successful in one eye. Almost overnight she was able to experience a whole new visual world, and she has had vision that was correctable to near-normal for the past 20 years.

Although researchers weren't aware of S.R.D.'s case until recently, her mother told a team led by Yuri Ostrovsky that it took several months for her daughter to be able to recognize basic objects and navigate the world using sight. Eventually she completed seven years of school, married, and now works as a maid. She can get around her town by herself and walks without a cane.

But what Ostrovsky's team wanted to know was whether S.R.D.'s visual system was truly normal. Using a laptop computer, they gave her ten different tests of the visual system, including visual memory, shape matching, depth perception, face/nonface discrimination, face identification, and gaze estimation. They gave the same test to another woman from India who had accurate vision and the same education level and social status. They also tested several Americans with similar visual acuity to S.R.D. (about 20/200).

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Links for Shireen Campbell's class

Mon, 10 Nov 2008 08:30:36 -0500

Today I'm visiting Shireen Campbell's class at Davidson College to talk about Cognitive Daily and other writing projects. This post collects the links I'll be using for class. If you're not in the class they might not be relevant to you, but they include some of our most popular posts, so maybe you'll enjoy reading them too!

For more, new links about psychology and neuroscience, visit this week's Encephalon at HighlightHEALTH.

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