Cognitive Daily

Smells we can't detect affect judgments we make about people

Thu, 09 Jul 2009 13:55:29 -0500

[Originally posted in December, 2007]

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 the rest of this post... | Read the comments on this post...

Is less always more?

Wed, 08 Jul 2009 10:08:51 -0500

My computer has over 5,000 songs on it -- 16.2 days' worth, according to my music-playing software. So how do I pick what song to listen to? More often than not, I just shuffle the whole list and play whatever album shows up on top. But if I'm in the car listening to the radio, I switch between the 10 or so local stations I've programmed in until I hear a song I like. I seem to be more likely to rely on my own judgment when I have fewer choices.

Some researchers have found similar effects with buying decisions: shoppers with just a few flavors of jam to choose from are more likely to buy than those given dozens of options (including the original choices). It's as if we're paralyzed when we have a large number of options to choose from, and so we end up getting nothing.

But is less always more? Most of the studies on number of choices have either given participants a very small or a very large number of options. Does this mean just one choice is the best? Or is there some larger number of choices that is optimal?

To find out, Avni Shah and George Wolford set up a table in a busy corridor at Dartmouth College and asked passersby to help their department select the best pen to order for its supply closet. They varied the number of pens sampled from 2 to 20. Each pen was similarly priced at around $2, and while each pen was different, all were "roller-ball" style pens with black ink.

After suggesting a pen, the passersby were given the option to buy the pen for a discount price of just $1 (they were told that the pens were valued at $2). One hundred students participated, and here are the results:

Read the rest of this post... | Read the comments on this post...

How do we recognize scenes?

Mon, 06 Jul 2009 17:34:59 -0500

Take a look at this movie (you'll need a video player like QuickTime or Windows Media Player installed in your browser to see it). You'll see four different outdoor scenes flash by, one at a time. The scene itself will only be displayed for a fraction of a second, followed immediately by a distraction pattern designed to mask any image left over in your visual system. Your job is to spot any desert or mountain scene. Watch carefully!

Did you spot them? What cued you in to the idea of a "desert" or a "mountain" scene? Was it a specific object in the picture (a mesa or a snowfield)? Was it a color? Perception research has historically focused more on the idea of objects or parts of objects (borders, curves) than entire scenes. But is that the way our visual system actually works? What if people are actually taking in the whole scene rather than (or in addition to) focusing in on individual objects?

Michelle Greene and Aude Oliva had 55 viewers rank hundreds of scenes for seven different more general properties: Concealment (C), Transience (Tr), Navigability (N), Temperature (Te), Openness (O), Expansion (E), and Mean Depth (Md). The pictures were presented on a 30-inch color monitor in groups of 100. So if a rater ranked pictures for Navigability, she would drag half the pictures (the least navigable) to the left of the screen, and the other half (the most navigable) to the right. Then these groups were each divided in half two more times, to create a spectrum of eight groupings, from least- to most- navigable. The least navigable pictures might be a dense forest or a steep cliff, while the most navigable might be an open field or a road. Every viewer didn't rate every picture or property, but at least ten viewers rated each picture for each property. Here's how the ratings broke down for four types of scenes:

Read the rest of this post... | Read the comments on this post...

When are highly-anxious women most anxious? When you least expect it

Thu, 02 Jul 2009 12:04:19 -0500

Take a group of 18- and 19-year-old women, college freshmen and sophomores. Then test them to find out who has the most social anxiety: who's most nervous about dealing with other people, particularly in public situations. What would be the most difficult thing you could ask these high-social-anxiety women to do? How about this:

I would like you to prepare and deliver a four-minute talk. This talk will be videotaped and viewed later by several professors and graduate students.... It is extremely important that you do the best job that you can with this talk.... Your talk should be about the most difficult time in your life and how you coped with it.

Now, give them five minutes to prepare, and allow their boyfriends to "help."

That's what a team led by J. Gayle Beck did; their goal was to see how socially anxious women and their romantic partners handled a difficult social situation. They asked women with low social anxiety and their partners to do the same task; 45 women in all participated. Of course, what the researchers were really interested was to see how the couples interacted while they prepared the speeches; in the end none of the women had to give a speech, and they were told their preparation session had been videotaped and would be analyzed for insights into how their relationship worked.

You might think that highly socially anxious women (which I'll abbreviate as HSA) would be more distressed about this than women with low social anxiety (which I'll abbreviate as LSA). You might also think that HSA women who weren't satisfied with their relationships would show more have more negative interactions with their partners than HSA women who were satisfied. And you'd probably speculate that if the boyfriends of HSA women made negative comments or behaved negatively during the preparations, that HSA women would show even more distress.

Beck's team predicted all three of these results, and were surprised to find that none of the predictions were supported by the study. They studied all the videos and rated the women along three dimensions:

Positive: Specific analysis of the problem, statement of feelings, asking for help, positive response to helper
Negative: Demanding help, criticizing, blaming, accusing, rejecting helper, whining, complaining
On Task: Staying focused on the assignment.

The boyfriends were rated on a similar scale.

Read the rest of this post... | Read the comments on this post...

The end of Cognitive Monthly

Wed, 01 Jul 2009 17:04:08 -0500

Due to exciting new career developments, I've decided to shelve Cognitive Monthly. I still think this sort of thing is a good idea, and CogMonthly was selling about as well as I expected. But I'm in the process of making a major career change (which should not affect Cognitive Daily), and something needed to be done to free up the time to do it. Expect another announcement here soon!

Read the comments on this post...

Do babies like color? If so, which ones?

Tue, 30 Jun 2009 16:23:45 -0500

New parents can come up with a seemingly endless array of vexing questions about their infants, from the best brand of stroller to the ideal song to sing them to sleep. The questions begin well before the child is born: what type of clothing should you purchase? What kind of crib?

One question Greta and I dwelled on quite extensively when Jim was an infant was color. We were renting an apartment and couldn't paint the nursery, so we wondered about the color of the toys we bought and the blankets and other bedding for the crib. Would a purple outfit be appreciated? What about a multi-colored activity gym? Would a white blanket be too boring? At the time, black-and-white toys were all the rage, the thought being that infants needed high-contrast objects to be stimulated the most.

While it is true that the youngest infants don't distinguish colors as well as older infants, by two months of age, most babies can tell the difference between most colors and white. Do they prefer particular colors? In 1975, M.H. Bornstein exposed infants to eight different pure colors of the same luminance and found that they looked longer at red and blue, and less at greenish colors like blue-green and especially yellow-green. This study may have been the inspiration for the yellow-green "Mr. Yuck" stickers intended to discourage toddlers from playing with poisonous substances.

But there are some problems with Bornstein's study. While the colors he showed babies had a similar luminance, the human experience of color perception actually varies across three different dimensions: hue, saturation, and brightness. We don't directly perceive the physical luminance and wavelength of a light, we perceive these other qualities. Even if only the wavelength of a light is changed, we'll see it as changing along all three dimensions: hue, saturation, and brightness. Perhaps babies actually prefer a particular saturation or brightness level, not a wavelength. This picture shows two of the three dimensions of color, hue and saturation:

Read the rest of this post... | Read the comments on this post...

Interview with Dave on guitar website

Fri, 26 Jun 2009 13:57:22 -0500

Jemsite, a website, forum and blog about guitars, has posted a fairly extensive interview with me about the psychology of music, Cognitive Daily, and other projects I'm working on. Plus, you can find out the name of Jim's Southern rock band, so head on over and check it out!

Read the comments on this post...

Nice analysis of why the Iranian election is probably fraudulent

Thu, 25 Jun 2009 09:59:07 -0500

There's an interesting article in the Washington Post today exploring one line of reasoning suggesting that the Iranian election is fraudulent. Basically, it comes down to this: the results aren't random enough. In a fair election, you'd expect that each digit, from 0 to 9, would be the final digit the results in each region roughly ten percent of the time: you'd see a vote count like 12,437 just as often as 12,435. But in fact certain digits come up more often:

The numbers look suspicious. We find too many 7s and not enough 5s in the last digit. We expect each digit (0, 1, 2, and so on) to appear at the end of 10 percent of the vote counts. But in Iran's provincial results, the digit 7 appears 17 percent of the time, and only 4 percent of the results end in the number 5. Two such departures from the average -- a spike of 17 percent or more in one digit and a drop to 4 percent or less in another -- are extremely unlikely. Fewer than four in a hundred non-fraudulent elections would produce such numbers.

You can't expect the first digits in a result to be random, because they represent tens of thousands of voters, and in any given region, one candidate probably is supported by more voters than the other candidates. But the final digits should be random in a fair election.

For some reason, people seem to pick numbers ending in "7" as more "random" than other numbers. When we asked our readers to generate random numbers from 1 to 20, 7 and 17 were the most common answers, appearing almost three times as often as you'd expect if the numbers were truly randomly generated. Meanwhile numbers ending in 5 only came up about half as often as they should have. In fact, our results were quite similar to the Iran election results for those digits:

Beber and Scacco also found that the patterns in the last two digits of each number are not random. They calculate the chance of these two anomalous results in the elections occurring due to chance as less than 1 in 200.

Read the comments on this post...

We're shockingly bad at noticing changes even to familiar scenes

Wed, 24 Jun 2009 15:37:50 -0500

Take a look at the following pictures of U.S. dimes. As you can see, they are slightly different from one another -- the date is in the incorrect spot on one of them. Can you tell which one is "wrong"?

Let's make this a poll:

Don't look at your pocket change before you answer! In case you don't have a dime handy, I'll reveal the correct answer later in the post.

Even though most Americans will say they know what U.S. coins look like, a similar study in 1979 found that people can't remember the basic details of a penny. More recently, change blindness studies have shown that we are very bad at detecting changes in scenes, even those that seemingly take place before our eyes.

But Luke Rosielle and Jeffrey Scaggs point out that change blindness isn't much of a problem in the real world because things don't ordinarily disappear or change right in front of our eyes, or in the moment when we glance away. A much more common type of change happens when we've been away for a longer period of time. If you leave town for a few weeks, you might be likely to notice that your favorite coffee shop has been repainted. This is the sort of change we may be more likely to notice. Or are we?

Read the rest of this post... | Read the comments on this post...

A rare instance where it's not better to be bilingual

Tue, 23 Jun 2009 14:01:41 -0500

I've always been amazed by people who are truly bilingual. While I've studied languages in school, I've never been able to seamlessly switch between languages, and even my best non-English language, French, is choppy at best. Compare this to the people I see in restaurants or on the subway, who can have conversations in two languages at once, speaking each language with equal fluency. They might tell a story in English, but save the punch line for Spanish. If a monolingual person talks to them, they instantly respond in the proper language, with hardly a second thought.

There are enough bilingual people in the world to suggest that they don't have some special ability that the rest of us lack; they've simply had more practice than others and learned it at a young enough age to ~~avoid an accent~~ achieve mastery. Some children are taught one language at home and another at school, or their parents each speak different languages, so they learn both. But still, the difference between monolingual and bilingual individuals is dramatic enough that you'd expect to find differences in other aspects of their behavior.

In fact, some researchers have found that bilinguals are better at certain tasks than non-bilinguals. One example is the Simon task, where two objects are flashed on the screen side-by-side. Respondents might press a button on the left when one of the objects is red and a button on the right when one of the objects is green. Bilinguals are better at the task than monolinguals when the object in question is on the opposite side of the button they have to push (for example, the green object is on the left but you have to press the right-hand button to indicate "green").

This makes some sense -- after all, a person who speaks both English and Spanish has had a lot of practice not speaking the wrong language, which may be similar to not pressing the wrong button.

But if it's possible for bilinguals to have better performance at some tasks, it's also possible that they might be worse at some things too. Consider the following movie:

Read the rest of this post... | Read the comments on this post...

Maps, directions, and video games: A model for how we perceive them

Thu, 18 Jun 2009 12:31:10 -0500

[Originally posted January, 2007]

Nearly all video games that offer a first-person perspective -- where the view on-screen simulates what a real person would see as she navigates through the virtual environment -- also include a virtual map to help in navigation. Even my favorite golf game has one. Such maps can be indispensable, but they also invite a question -- should the map rotate to align with the player's viewing angle, or should they remain at a constant orientation?

Aligning the map with the viewer's perspective makes it easier to find items, but constantly rotating the map might make it difficult for gamers to remember where those items are located when they move out of view -- when the object is needed, the map might be upside-down compared to when the object was first encountered.

Of course, maps aren't just useful for games -- more and more cars are equipped with GPS navigation systems, and hikers like myself like to use the old-fashioned paper type to help find campsites in the wilderness. Creating maps that are easy to compare to the first-person viewpoint, whether in a video game or an Air Force jet, can mean the difference between life and death.

Research on map orientation has found that mapreaders take locate items they see in a scene on the corresponding map at different rates. As you might expect, the more the map is rotated compared to the viewing angle of the scene, the longer an object takes to find, with upside-down maps taking the longest. But there is a secondary effect, which depends on the location of the object in the scene. Items directly in front of the viewer are located fastest, regardless of the orientation of the map. As the items move to the right/left and farther away, they take longer to find. But items that are farthest away, near the back of the scene, are found nearly as quickly as items directly in front of the viewer.

Take a look at this simple scene, made using the customizable video game Unreal Tournament:

Read the rest of this post... | Read the comments on this post...

Self-refilling bowls: An idea whose time should never come

Wed, 17 Jun 2009 10:48:51 -0500

[Originally posted in April 2007]

One "trick" dieters often use is to put their food on a smaller plate. The idea is to fool yourself into thinking you're eating more food than you really are. But doesn't our stomach tell us how full we are?

Actually, it doesn't. Brian Wansink has devoted his career to studying how perception of food intake relates to actual eating behavior. Together with James Painter and Jill North, he's come up with a dramatic demonstration of how wrong our stomachs can be.

Volunteers were recruited to participate in a soup-only lunch in a room adjoining the school cafeteria. They filled out a form asking about color preferences, then were seated a table with four different-colored bowls. The colors were just a distraction: the real purpose of the study was to see how much people would eat when their soup bowls refilled automatically.

Two of the participants ate from self-refilling bowls; the other two had their bowls refilled by a server. Everyone was encouraged to eat as much as they wanted. The self-refilling bowls involved a fair bit of cooking technology -- plastic tubes connected a soup pot next to the table to the underside of each bowl. The refill rate of the bowls was adjusted so that the bowls could be filled completely in 20 minutes -- the duration of the study. Technically the bowls could be nearly empty by the end of the session, but each bowl held 18 ounces of soup, so this would have required consuming over a quart of soup!

Despite the fact that everyone's bowls were refilled, the people eating from self-refilling bowls ate 73 percent more soup. Even more surprising is that they didn't feel any different from people who ate from manually-refilled bowls:

Read the rest of this post... | Read the comments on this post...

Test your boundaries -- then find out how you made them

Mon, 15 Jun 2009 10:21:04 -0500

[Originally posted in February, 2007]

When you look out the window and then look away, how do you remember what you saw? Do you hold a picture of the window in your head, frame and all? What about a photo? Do you remember the physical photo, or do you imagine the real scene it represents? If you remember the scene, and not the photo, then how do you form the boundaries of the scene? Does your memory end precisely where the photo does?

Here's a little test to see how accurate your short-term memory of a photo is. When you play the movie below, you'll have a second to get ready, then a photo will flash for just a half-second. It will be replaced by a random pattern for two seconds, and then the photo will reappear. It might be the same as the original, or it might have been cropped or enlarged slightly. Your job is to say if the area depicted in the second photo is the same, larger, or smaller than the original.

Click to play movie (QuickTime Required)

What do you think? Let's collect the answers in a poll (don't repeat the movie until you've responded):

Even playing the movie repeatedly it might be difficult to tell, so I'll display both photos side-by-side at the end of the post. What we're exploring here is a phenomenon that's been investigated for several years by Helene Intraub and her colleagues:

Read the rest of this post... | Read the comments on this post...

Musical SNARC: Do we have a musical scale in our heads?

Thu, 11 Jun 2009 17:15:44 -0500

There's lots of research suggesting that we may have something like a "number line" in our head: The SNARC effect says that if you normally read numbers from left to right, you're faster to react to small numbers with your left hand, and big numbers with your right hand. Similar research has also found a SNARC effect for letters (a SLARC effect?).

So it might make sense that there would be a similar effect for musical notes. You might call it a SMARC effect, but if you only hear one note at a time it's not really "music." Undaunted, a team led by Pascale Lidji has conducted several experiments on what they call the SPARC effect (spatial pitch association of response codes). In many languages, "low" and "high" are used to describe both musical pitches and physical position. Low notes on a piano are played with the left hand, while high notes are played with the right.

Lidji's team's basic experiment is simple. Sixteen students listened to musical notes, and were told to press a button to the left if the note was played on a piano, and to the right if it was played on a violin (the button assignments were switched halfway through). They heard almost 200 notes, but they were selected from just four pitches: C3 (one octave below middle C on a piano), G3, E5, and B5. The students were all non-musicians, and their results were compared to the results for 16 musicians (some students, some professionals, all with over 8 years of musical training). Here are the results:

This graph shows the difference in right-hand versus left-hand reaction times -- so if the right hand was slower to react, you see positive number, and if the left hand was slower, the number is negative. For non-musicians, there is no SPARC effect: there was no systematic difference in reaction time based on musical pitch. But for musicians, the right hand was slower to react to low notes and faster to react to high notes: that's a bona-fide SPARC effect.

Read the rest of this post... | Read the comments on this post...

Babies as young as six months prefer different toys based on sex

Wed, 10 Jun 2009 15:37:41 -0500

When Nora was born, Jim was just 19 months old, and still unable to communicate other than with the most basic words (ba-ba, da-da, na-na). But we could tell right away that while he liked his new sister, he was a little jealous when our attention was focused on her needs, instead of his, as they had been his entire life. So we decided to get him a little baby doll, a boy, which he called "Seth." When we fed Nora, Jim fed Seth. When we changed her diapers, he changed Seth, and so on.

This was an effective distraction for a few months, but eventually Jim decided it was too much work caring for Seth and went on to other distractions, like emptying all the kitchen cupboards or running around the apartment like a mad banshee. He kept Seth for many years, but when he was around ten years old he must have decided that it was embarrassing to own a doll because we found it hidden in the deepest recess of his closet.

Psychologists have wondered for decades whether boys preferred "boy toys" because of a natural inclination to like hard, mechanically-oriented things, or simply because those around them encouraged them to play with the toys they felt were appropriate for boys. Similarly, do girls "naturally" like to play with dolls, or are they encouraged to do so by their parents? While researchers have found that kids around 18 months and older do prefer the traditional gender-specific toys, research for younger kids (presumably less-influenced by their parents) is less clear-cut.

A 2000 study showed babies between 3 and 18 months old pictures of toys traditionally preferred by each gender and measured how long boys and girls looked at the pictures. The boys as young as 9 months old seemed to prefer toys like balls, blocks, and cars to dolls, dustpans, and ovens. However, even the 18-month-old girls showed no apparent preference for any type of toy based on how long they looked at them.

One problem with this sort of study is that it's not very precise: is the baby really focusing on a particular toy, or just pointing its head in that general direction?

Read the rest of this post... | Read the comments on this post...