Wednesday, May 30, 2012

Comparison and choice: When something is better than nothing

Several years ago, I was buying a car, and the dealer had a promotion where the interest rate for financing the car was 0.99%.  It seems a little strange to charge such a low interest rate.  The finance company does not make a lot of money on that rate.  You might think they would attract even more buyers if they interest rate was 0%.  That increase in sales ought to make up for any difference in interest payments on the cars that are financed.

There is some reason to think, though, that a 0.99% finance rate would actually attract more buyers than the 0% rate.  This strange idea comes out of theories of the way people make comparisons when they make choices. 

In a 1993 paper in the Journal of Memory and Language, Dedre Gentner and I found that when people compare two things, they tend to focus on properties that the objects share over those that one object has that the other is missing.  For example, when comparing two cars from different dealers, you might focus on the size of the engines in each car or the trunk space.  If one car has extra rollover protection and the other doesn’t, you might focus less attention on that detail than on the properties that both cars share.  Some studies I did with Doug Medin published in a 1995 issue of Organizational Behavior and Human Decision Processes confirmed that people often ignore these unique properties when making choices.

A paper by Mauricio Palmeira scheduled to appear in the July, 2011 issue of the Journal of Consumer Research carries this work a step further.  He finds that making a unique property of an option comparable can increase the attention given to that property, even if the change makes the option objectively worse.

Let me unpack that.

Let’s go back to the interest rate example.  Suppose you are comparing two cars with a similar price.  They might be very similar along most dimensions.  Brand A might have a slightly larger engine than Brand B.  Based on the engine size alone, then, you might prefer Brand A.  The dealer for Brand A charges a 6% interest rate to finance the car.  If the dealer for Brand B charges 0% interest, then you would think that would be very appealing.  But 0% interest also makes the comparison of interest rates feel like a comparison of something against nothing.  Following all the work I just described, people might actually ignore this dimension and choose just based on the size of the engine. 

But what if you made the finance charge 0.99%?  This interest rate is clearly worse than 0%.  It is better to pay nothing than to pay something.  But, it does make the interest rate a point of comparison for the brands.  That means that offering a slightly higher interest rate might actually entice more people to buy the car.

Does this really happen?

In a number of studies involving choices between products like CD players, credit cards, and yogurts, he found that people tended to ignore a dimension when it had a value of 0.  Making the value slightly higher got people to pay attention to the value and increased choice of the option.

For example, in one study people chose between two credit cards.  Brand A had a higher annual fee than Brand B.  One group was told that Brand A offered a 0% annual interest rate and Brand B offered a 20% interest rate.  About half the people chose Brand A in this group.  A second group was told that Brand A offered a 1% annual interest rate and Brand B offered a 20% rate.  In this group about 3/4 of the people selected Brand A.  So a slightly higher interest rate was actually more effective at attracting people toward Brand A.

What does this mean for you? 

When you are making important choices, it is useful to make a table of the key properties of each option.  The table will have zero values in some of the entries.  You should be aware that you may be prone to ignore those zero values, so a table gives you a way to focus on the values that are missing.

This table might also make you do a bit more research about the choice you are making.  Research by Chris Hsee and his colleagues has found that one reason why people have trouble with missing values is that they find those dimensions hard to evaluate.  Suppose you find out that a particular car has rollover protection and the other doesn’t.  Is rollover protection an important feature to have in that kind of car?  Answering that question requires doing some more work to find out what experts think. 

Ultimately, you want to make sure that you use as much of the information about the options as you can in this decision situations.

Thursday, May 24, 2012

Understanding what we learn from not doing by looking at the brain

When you think about thinking, you probably focus most often on your ability to make decisions or solve complex problems.  An important part of your thinking abilities, though, is the ability to predict what is going to happen in the future. 

Some of those predictions involve sequences that are predictable.  Anyone who has listened to a CD (or record, cassette, or 8-track) often knows that you start to hear the first few notes of the next song on the album after a song ends.  Even though you did not try to learn what was coming next, your brain naturally helps you to make this prediction. 

Other predictions involve actions.  When you press down on the turn signal in your car to make a left turn, you expect to hear the repeated click of the turn signal.  If you don’t hear the sound after you engage the turn signal, you might look at the dashboard to make sure that the turn signal is actually on.  You are able to do this, because you have made a mental connection between an action and an outcome. 

One question of interest to researchers was whether people could also learn to predict what would happen when they made the choice not to act.  One the one hand, choosing not to do something is still a choice, and so there is some information about that decision in the brain that could be used as the basis of the prediction.  On the other hand, choosing not to act means that there is no information about a specific action that could be used to help the brain predict what is going to happen.

The problem with studying a question like this is that you need to have something to measure.  Traditional measurements in psychology involve actions, which makes it hard to study what people do when they are choosing not to act.

To address this problem, Simone Kuhn and Marcel Brass turned to brain imaging in a study published in the December, 2010 issue of Cognitive, Affective, and Behavioral Neurosciences. 

In this paper the researchers first trained people about what would happen both when they acted and when they did not act.  In this study, people sat in front of a computer.  Periodically, an orange dot would flash on the screen.  When this happened, people had to make the choice either to press buttons in front of them with each hand or not to press the buttons.  (People were asked to use both hands because that would ease the interpretation of the later part of the experiment in which images of their brains were taken.)  The participants were asked to press the button on about half the trials, but to make the choice as randomly as possible.  In this training part of the study, every time participants pressed the buttons, they heard a high tone as feedback.  Every time they chose not to press the button, they heard a low tone as feedback.

After this training, people were put in an fMRI scanner.  The scanner allows researchers to measure changes in blood flow to different parts of the brain over time.  Because areas of the brain that are active require a lot of energy, lots of blood will flow to regions that are very active when a particular task is being performed.  This blood flow brings the nutrients needed for the brain to stay active.

After being put in the scanner, people did three different tasks.  In one task, they saw the same orange dot, and they had to decide (as before) whether to respond or not.  This time, though, no tone was played as feedback.  In another part of the study, people saw either a red dot or a yellow dot.  When they saw the red dot, they had to press the button.  When they saw the yellow dot, they had to avoid pressing the button.  Again, they received no feedback.  In the last task, they just listened to tones.

The researchers first confirmed that when people listened to tones, that the areas of their brain that normally respond to tones (the auditory cortex) would show increased blood flow.  Then, they looked at what happened in auditory cortex in the other tasks.  When people pressed the button in response to the red dot, then auditory cortex was also active, but when people did not act in response to the yellow dot, auditory cortex was not active.  This result shows that when people are responding based on some event in the world, then they do not predict what might have happened if they did not respond.

The interesting result came when people chose either to respond or not to respond to the orange dot.  In this case, auditory cortex was active both when people decided to respond and when they did not.  That is, the practice session of the experiment led people to predict that when they chose not to respond that they would hear a tone.

There are a few interesting aspects to these findings.

On the scientific side, these results demonstrate how brain imaging can be used to study something that would be difficult to study otherwise.  It is hard to get people to state reliably whether they are imagining a particular sound.  Having a more objective measure (like activity in the brain) helps to measure things that would be hard to detect otherwise.

On the practical side, these findings show that your brain treats your choice not to respond to something as if it was an action.  That is useful.  There are many situations in life where the right thing to do is to refrain from acting in a situation.  If someone cuts you off on the road, for example, then it is a healthy thing not to yell at them or to make some kind of gesture.  Happily, your brain has mechanisms in it that allow you to make good predictions about what will happen in those situations when you choose not to act.

Monday, May 21, 2012

What you do affects what you learn

Part of learning about anything new involves learning about the objects and individuals in that arena.  If you are watching football for the first time, before you can understand the rules, you have to know about the field, the various players, and objects like helmets and the football itself. 

This issue is particularly important in classroom settings. Part of the science curriculum, for example, teaches students about the way the world works.  If you are going to learn about oceans, then you need to learn about the kinds of animals that live in the ocean before you can understand the ecosystem of the ocean. 

So, what is the best way to teach people about objects?

This question was taken up in a paper by my colleague Brad Love and his former student Yasu Sakamoto in the December, 2010 issue of the Journal of Experimental Psychology: Applied.

A traditional way to teach people about new objects (like the fish in the ocean) is to have them learn to classify different objects.  I remember having to do a leaf collection in 7th grade, in order to learn to classify the various trees in my neighborhood.  In classification, you see the various properties of objects (like sharks, fish, and plants) and you learn to identify the category that they come from. 

There are other ways to try to teach people about things, though.  In a 1998 paper in the Journal of Memory and Language, my former student Takashi Yamauchi and I introduced a technique called inference learning.  When doing inference learning, people are told what category something belongs to and have to predict some of the features it might have.  You might see a particular shark and ask how many pups it normally has. 

Sakamoto and Love compared learning through classification to learning through inference in a set of elementary school students.  The students were learning about sharks in the ocean.  The students learned about some sharks by learning to classify them.  In classification, they would see an animation of a shark described by properties like its size, eating behavior and number of young that it has.  After seeing the shark, they would have to state the type of shark it is. 

In inference learning, the students would be told the type of shark (“This is a Tiger Shark”), and they would see some of its properties (like its size and eating habits) and had to predict some other property (like the number of young it normally has).  Across different questions, students would have to predict values of different properties.

Even though classification is frequently used in classroom settings, inference learning was much more effective.  Students were able to remember more about the sharks even a week later if they learned about that shark by predicting properties it has than if they learned about it by classifying it.  They were even able to learn some information about the properties of the sharks that they were never asked about, though they learned less about these properties than about the ones that were the focus of learning.

The results of this study fit with a growing understanding of the way people form categories.  The knowledge that we store is set up to help us act on the world.  As a result, we draw on the procedures we used when learning something to determine what we might need to know about that item when we encounter it again.  If we just learn to classify items, then the cognitive system assumes that the most important thing about the object is that we be able to identify it again in the future.  As a result, we learn only enough about the object to be able to figure out what category it belongs to.

When we have to predict a range of properties about things, though, then the cognitive system assumes that we need to know a lot about it.  As a result, we seek to understand the variety of properties that the object has to ensure that we will be able to make accurate predictions about it in the future. 

When we teach about things in school, then, we have to be careful to get students to interact with the information in ways that will help them to use that information later.  Asking students to make predictions about aspects of new items is one powerful way to ensure that they learn about them effectively.

Sunday, May 20, 2012

Commencement Speech, 2012

I had the opportunity to give the commencement speech for the Psychology Department graduates at the University of Texas on May 19, 2012.  Here it is
It is an honor to be speaking to all of you today.  Before I really get started, I want all of the graduates; the proud parents, relatives, and friends; and my colleagues on stage here from UT to enjoy this moment. 
It is funny, but we all celebrate a lot early in life.  There are now graduation ceremonies from Kindergarten, elementary school, middle school, high school, and finally college.  As we get older, though, we spend less time celebrating our own achievements.  Eventually, it seems that we just complete things and move on.  In my opinion, it is always worth celebrating our achievements. So, drink this moment in.  And remember to take time to enjoy the things you have done.
Ok.  Now back to business.
I have one last opportunity to say something enlightening to all of you.  Here goes.  “You just never know what is going to happen in life.”  That’s it. 
Because you never know what is going to happen, though, you need to be open to life’s possibilities.  Even the ones you are not expecting.  And you need to help the people around you to be open to fulfilling their potential.
There are three ways to do this.
First, keep learning.
You never know where your next good idea is going to come from.  Take the example of Swiss engineer George de Mestral.  He came home after walking his dog and spent some time pulling off the cockleburs that stuck to the dog’s fur.  Rather than just be annoyed at the nuisance, he wanted to know what it was made the cockleburs stick so persistently to the fur.  He examined them under a microscope and discovered that the cockleburs had little hooks on them that allowed them to stick to the dog’s tangled fur.  From this observation, he had an idea.  He then found some cloth manufacturers and got them to create a synthetic set of cocklebur hooks and some synthetic dog fur.  In the end, he used them to create the reusable connection we call Velcro.
You just never know.
The second thing you need to do is to let the world tell you unexpected things.
Over the course of my career, I have spent a lot of time running experiments.  Without a doubt, the most exciting studies have been the ones that did not come out as I expected.  There is a temptation to look at these surprising results and to be disappointed that the experiment did not work. 
But, every well-run experiment works. 
The beauty of running studies is that every once in a while the world is more interesting than you thought it was.  That means you have to be open to recognizing that the world is telling you that you are wrong.  In those situations, you have to re-think your beliefs about the world and ask new questions in order to understand it.  If you listen to the world around you, though, you open yourself up to incredibly rewarding experiences.  I truly have learned more from the experiments that “didn’t work” than from those that came out as I hoped.
You just never know.
The third thing you need to do is to encourage the people around you.
I was thinking about this last month when I opened the alumni magazine from Brown University where I got my undergraduate degree and saw that a math professor I had named Frank Stewart had passed away.  He was in his 90s and had a long career.  Professor Stewart taught my linear algebra class.  He was a real education innovator.  He developed a lot of his own software to teach math, and designed an elegant curriculum to go with it.
But, he was also a great person. 
When I took his class, I completely flubbed the first exam.  It was one of those exams where you go in certain that you have nailed the material only to watch your confidence evaporate with each successive question.  After getting back the graded exam, I went to his office and asked what I should do.  He just smiled and told me two things.  First, I should come back to his office whenever I had a question about the material.  Second, he said that many of the people who did best in his class started off with horrible scores on the first exam. 
Encouraged, I kept at it.  He gave an innovative take-home final exam in which each of us had to discover the final set of principles in this class by ourselves.  He guided us through this process by the structure of the exam itself.  Ultimately, I had one of those wonderful moments in which clouds parted, the choir sang in my head, and I truly understood the material.  I was so excited, I actually left my dorm and hurried across campus just to stick my head in his office and say, “I got it!”
If he hadn’t been so encouraging, though, I would not have gotten it.  I might just have dropped the class and never had that beautiful experience.
You just never know.
Graduates, as you prepare to leave the University of Texas, remember to be open.  If the branding folks here are right and “What happens here changes the world,” it is not because there is some specific fact that you learned in your classes that will change you.  It is that you learned how to learn.  You learned to let the world tell you things—even those things you may not have wanted to hear at the time. And—I hope—you have learned to help the people around you to see the possibilities in front of them, even when they may think they have failed.
So, for now, spend a few days to celebrate your accomplishment surrounded by your family and friends.  Then, go off and do great things.  And every once in a while come back and tell us what you have been up to. 

Thursday, May 17, 2012

Using the conflict between doing and not doing

There are many activities in your life where you might choose between doing an action and not doing that action.  Many years ago, I became a vegetarian.  I had a number of reasons for doing that.  I wanted to eat a healthier diet.  I also felt that raising animals for food was a poor use of land and water resources.  In the years before that, I chose to eat meat.  Even though these two actions are opposites, my reasons weren’t opposites.  I was not hoping to eat an unhealthy diet and uncaring about water and land resources before that.  Instead, I ate food that the people around me ate, and I ate foods that I enjoyed. 

A paper by Juliette Richetin, Mark Conner, and Marco Perugini in the January, 2011 issue of Personality and Social Psychology Bulletin explored the contribution of these kinds of goals for people’s choices of what seem to be contradictory actions.

First, they documented the point described in the first paragraph in three studies.  The first experiment actually focused on people’s goals related to eating meat.  The other studies explored the decision to exercise and the choice of mothers to breastfeed or formula feed their babies.

In that first experiment, they had people rate their attitude toward eating meat as well as their attitude toward not eating meat.  They also had people rate whether the people around them did or did not eat meat and whether they felt that the decision to eat meat or not was under their control.  They asked people for their intentions to eat meat, and then tracked whether people actually did eat meat over the next two weeks.

If the goals relating to eating meat and not eating meat were opposites, then you would expect people’s attitudes toward eating meat and toward not eating meat to be completely opposite.  They are not complete opposites.  Unsurprisingly, the strength of people’s attitudes is negatively correlated.  That is, the more you want to eat meat, in general the less that you want to avoid meat.  But, the correlation in the strength of these attitudes is moderate.

Interestingly, both the attitude toward eating meat and the attitude toward avoiding meat both influence people’s later behavior.  That means that people who had only a strong attitude to avoid meat tended to eat very little meat (if any).  That is, the stronger people’s attitude to eat meat, the more likely they were to eat it.  The stronger people’s attitude to avoid meat, the more likely they were to avoid it.  People who had strong attitudes both to eat and to avoid meat experienced a conflict between these attitudes and they ate moderate amounts of meat.   A similar pattern was observed in the other studies exploring other pairs of goals.

What does this mean for you?

In many situations, when you want to change a behavior, you aim to switch from something you are doing to something you no longer want to do.  There is a tendency in this case, to focus on negating the reasons for your previous behavior.  If you want to quit smoking, you might focus on the reasons you used to smoke.

This work suggests that an effective strategy for changing behavior is to change the kinds of goals you have to support the behavior your desire.  If you don’t want to smoke any more, then don’t focus on the goals that you used to have surrounding smoking.  Instead, create new goals around health and exercise.  Those new goals will influence your smoking by pushing you toward other behaviors rather than just pushing your away from smoking.

Monday, May 14, 2012

Using awareness to increase willpower

I have talked about willpower a number of times in this blog.  The basic story so far has been that exercising a lot of willpower at one time can make it harder for you to successfully avoid a temptation later.  Stress can also make it harder to resist temptations.

However, there have been a number of factors that can improve willpower as well.  For example, I wrote recently about a study suggesting that if you believe that exerting willpower once makes you stronger in the future, then you actually become better at resisting temptations in the future.

A paper in the January, 2011 issue of the Journal of Experimental Social Psychology by Hugo Alberts, Carolien Martijn, and Nanne deVries suggests that self-awareness can also improve your ability to overcome obstacles even after having to exert a lot of self-control in another situation. 

In their study, the main measurement of success at self-control was the length of time that people could hold a handgrip closed.  Exercise handgrips are easy to close at first, but the continued resistance eventually becomes painful.  The longer you hold the handgrip, the more that you are exerting some control rather than giving into the temptation to stop. 

(As a side note, the way that they measured the amount of time that people could hold the handgrip was interesting.  They had people close the grip and they put a quarter in between the handles.  As soon as the person relaxed even a little, the quarter would fall to the ground and the clock would be stopped.)

The study started with a baseline measure on the handgrip that would take into account differences between people in their strength.  After that, some people did a difficult task in which they had to solve difficult math problems while hearing distracting noises.  A second group solved easier problems with no distracting noise.  Previous research suggests that doing this harder task for a while makes it harder to exert willpower later.

Now, people performed what they thought was an unrelated task in which they unscrambled sentences.  Some people got sentences that repeatedly used the word “I.”  For example, they might see the words some bread I buy and would have to unscramble that into the sentence “I buy some bread.”  Other people saw similar sentences, only the word “I” was replaced with other people’s names.  The idea was that this unscrambling task would make participants think more about themselves than those who heard other people’s names. 

Ok, so what happened?  The people who unscrambled sentences with other people’s names in theme showed the usual effect of a difficult self-control task.  They were found it harder to squeeze the handgrip the second time after they performed the difficult self-control task than after the easy task.

The people who unscrambled sentences with the word “I” showed a different pattern.  They did just as well squeezing the handgrip after the difficult self-control task as after the easier self-control task.

What does that mean for you?

If you are in a situation where you have had a rough day, you should know that there is some chance that you will have difficulty resisting future temptations.  To help you out, spend a few moments thinking about who you are and who you really want to be.  This additional self-awareness will help to inoculate you against new temptations and make it more likely that you’ll use your willpower successfully.

Friday, May 11, 2012

It matters whether you believe in willpower

I have written a few times about factors that affect willpower.  Willpower is the name that we give to the mechanisms (most of which involve the frontal lobes of the brain) that prevent us from carrying out a behavior we really want to perform. 

Over the past several years, there have been a number of studies showing that if you make people work hard to control their behavior, then they have difficulty continuing to use willpower in a later situation that calls for preventing behavior.  The idea that willpower is a resource that can be used up is called ego-depletion.  It has been studied extensively by Roy Baumeister, Kathleen Vohs and their colleagues.

A paper by Veronika Job, Carol Dweck, and Gregory Walton in the November, 2010 issue of Psychological Science suggests that one factor that affects whether you show ego-depletion effects is whether you believe that willpower is a limited resource.

In one study, they asked people a number of questions about willpower.  Some people gave answers suggesting that they believe that willpower is a limited resource.  Other people gave answers suggesting that willpower is actually an unlimited resource.

Later in the study, people did a difficult task that was either relatively easy or one that was hard.  The easy task involved crossing out all of the letter es on a page of written text.  The harder task asked people cross out all of the ‘e’s for a while, and then switch so that they crossed out every ‘e’ except for the ones that were followed by another vowel.  This task is difficult, because people have to prevent themselves from doing a behavior that they had already built up some habit to perform.

After doing this task, people performed a Stroop task.  In the Stroop task, people see words naming colors that are written in a colored font.  People have particular difficulty naming the color of the font when the word is the name of a different color.  For example, people are prone to make mistakes when they see the word “yellow” written in red font. 

Putting all this together, people who believed that willpower is a limited resource made more mistakes on the Stroop task following the difficult letter-crossing task than following the easy letter-crossing task.  That is, these people showed the typical ego-depletion effect where doing one difficult self-control task makes it hard to do a second. 

In contrast, the people who believed that willpower is essentially unlimited did equally well no matter which letter-crossing task they did.  That is, those people who think that willpower is unlimited did not show the ego-depletion effect.

Now, it is possible that there are just differences between people.  Some people have limited willpower resources and others don’t.  On that view, it isn’t that your beliefs about willpower affect your performance, but rather that your beliefs about willpower reflect your actual abilities.

To explore this possibility, a second study actually manipulated people’s beliefs about willpower by using a biased questionnaire.  One version of the questionnaire got people to agree with statements suggesting that willpower is a limited resource (“Working on a strenuous mental task can make you feel tired so that you need a break before accomplishing a new task.”)  A second version used a questionnaire that got people to agree with statements suggesting that willpower is unlimited (“Sometimes working on a strenuous mental task can make you feel energized for further challenging activities.”) 

After these questionnaires, the groups did the same tasks as before.

In this study, the group that was biased to believe that willpower is limited did more poorly on the Stroop task following the difficult letter-crossing task than following the easy one.  In contrast, the group that was biased to believe that willpower is unlimited did just as well on the Stroop task regardless of which letter-crossing task they did.

Taken together, these studies suggest that people’s beliefs about their own willpower are one factor that affects how effective their willpower will be.  The more that you believe that willpower can keep you from doing things that you don’t want to do, the more likely you will be to use your willpower successfully.

All this suggests that it is well worth believing in willpower.

Monday, May 7, 2012

Why cell phones are so annoying

Sometimes when I’m thinking having trouble deciding what to write about for my next blog entry, fate steps in.  I was sitting at the airport getting ready to fly to Dulles airport trying to get some reading done.  Unfortunately, I was having a hard time concentrating.  There was a guy standing behind me with a Bluetooth receiver in his ear jabbering away to someone in his office.  Every time I managed to start reading again, my attention would be wrested from the page to hear half of his conversation. 
Before I was moved to an act of airport-terminal-rage, I was saved by the boarding announcement.  I got on the plane and pulled out the October, 2010 issue of Psychological Science.  In it was an article by Lauren Emberson, Gary Lupyan, Michael Goldstein, and Michael Spivey that demonstrated exactly what was going on for me.
The authors pointed out that there are two problems with overhearing cell phone conversations.  First, you only hear half the conversation.  When there are two people sitting behind you talking (that is having a dialogue), you get both sides of the conversation, and so you can follow what is happening.  If one person recites a monologue, the text is coherent (though I’d be a bit concerned about someone monologuing in an airport).  Cell phone conversations, though, give you only half of the conversation.  You can’t hear what the person on the other end is saying, and so the speech you do hear is not that coherent.  The authors call this a halfalogue.
Second, the overheard conversation seems to start and stop at random.   It is hard to predict when the speaker is going to start and stop, because you can’t hear the other side of the conversation.
The authors of this study demonstrate that hearing a halfalogue is particularly draining of your attention resources.  They had people do two difficult tasks.  In one, they had to track a randomly moving dot on a computer screen with the mouse cursor.  In another, they had to remember a set of letters, and press a button whenever one of those letters appeared on a computer screen.   While they did this task, people heard either a conversation between two friends, half of that conversation (as if they were hearing a cell phone conversation) or they heard a monologue that summarized a conversation between friends.  The dialogue and the monologue did not affect people’s performance on these difficult tasks much.  But, the halfalogue was devastating.  People’s performance got much worse when hearing just half the conversation.
Then, the authors did a clever manipulation to demonstrate why this happens.  They took the dialogue and the halfalogue and filtered the signal so that it sounded vaguely speech-like but was not understandable.  They had another group of participants do the same tracking and memory tasks listening to this filtered speech.  Neither the filtered dialogue nor the filtered halfalogue affected people’s performance on the difficult tasks.  That suggests that the problem with cell phone conversations isn’t that the sound starts and stops at seemingly random points.  Instead, it indicates that when you hear a cell phone conversation, you can’t help but try to pay attention to what the conversation means.  Because you’re only getting half the conversation, though, you can’t really understand it, and that drains attention.
On the positive side, now I know why it is so annoying to hear cell phone conversations in public places.  On the negative side, it doesn’t appear that there is much I can do about it.  Maybe Brookstone sells some kind of Bluetooth jamming device…