Tuesday, March 19, 2019

Your Memories Are Not Fixed in Stone


One of the scariest parts of the legal system is its reliance on eyewitness testimony.  A witness identifies who a defendant as the perpetrator of a crime can sway a jury in the absence of any physical evidence that that the defendant was actually the one who committed the crime.
For several decades, of course, we have known that eyewitness memory is faulty.  In the 1970s, classic studies by Elizabeth Loftus and her colleagues demonstrated that people would mix together information they saw and things they heard in later questions when thinking back to an event.  In a 1974 paper written with John Palmer, participants watched a film of a car accident.  Later, participants were asked to judge how fast the cars were going.  Some people were asked how fast they were going when they hit each other, while others were how fast they were going when they smashed into each other.  A week later, participants were asked whether the saw broken glass in the accident.  Those who were asked about the cars smashing into each other were much more likely to say they saw broken glass than those who were asked about the cards hitting each other.
On the basis of results like this, there are two possibilities.  One is that when we remember things, we recreate our memory based on fragments of actual memories from the past.  This view of memory suggests that we may make mistakes when we do this reconstruction, but somehow the truth is still buried in our memories somewhere. 
A second possibility, though, is that when we are reminded of the initial situation, our initial memory is actually opened up again in ways that allow it to be altered. That is, over time the initial memory may be gone completely and replaced with a revised version.
For a long time, the first of these possibilities was the one that was generally assumed by the field.  More recently, though, studies suggest that our initial memories themselves may be changed in the future through a process called reconsolidation.  In reconsolidation, a memory is made active again, and while it is active, it is subject to change.
One example of reconsolidation in people comes from a 2007 study by Almut Hupbach, Rebecca Gomez, Oliver Hardt, and Lynn Nadel published in Learning & Memory.  They had participants two lists of words over a three-day period. 
On the first day, participants learned a list of 20 words that named common objects.  They practiced the items until they could recall at least 17 of the 20 items on the list.  On Day 2, some participants were reminded that they had learned a list on the previous day.  Others were not given a reminder.  These two groups then learned a second list of words naming a different set of common objects.  A control group did not learn the second list.  On the third day, participants returned and were asked to remember as many of the words from the first list as possible.
The control group recalled about half of the words on the list.  The group that was not reminded of the list that they learned on the first day recalled 45% of the words, and occasionally also recalled one of the words from the second list (about 5%).  The group that was reminded of what they did on the previous day recalled only about 36% of the words from the first list.  Interestingly, they also recalled about a quarter of the words from the second list they learned.
This finding suggests that just reminding people of the experience of learning the first list led people to combine their memory of the first list with that of the second.  Two control conditions refined this finding a bit.  In one study, participants recalled the first list immediately after learning the second list.  In this study, participants did not recall any of the items from the second list when remembering the first list.  This finding suggests that it takes time for the memory of the second list to be combined with the memory of the first list.
Another control condition looked at memory for the second list.  This study found that when people recalled the second list, they rarely also added words from the first list to it, even when they had been reminded that they had learned the first list in the previous session.  This study suggests that it is only the initial memory that is being affected by a later experience.
Putting all of this research together suggests that it is possible to rewrite aspects of our old memories with new information that was acquired after the initial memory was created.  These findings are particularly frightening when it comes to things like eyewitness memory, because it suggests that even if people were able to recall things correctly at some point in the past, that “truth” may no longer exist anywhere in memory.
This is just one more reason why the legal system needs to treat eyewitness testimony carefully.  After all, if old memories have been altered by new information, then the witness will believe deeply in their testimony, because it reflects their actual memory.  Unfortunately, that actual memory is not an accurate reflection of the past it represents. 

Tuesday, March 12, 2019

Bring Your Brain to Work is coming!


Hey everyone. I'm excited to start introducing Bring Your Brain to Work to the world. Over the next few months, I will be posting videos discussing topics that I'll be covering in the book. But, first a quick promo...




Monday, February 4, 2019

Social Comparisons Can Make You Give Up


Competition can often be motivating.  The history of discovery and innovation is filled with stories of people who were spurred on by the prospect that someone else would beat them to the goal.  Watson, Crick, and Franklin were concerned that other groups were also closing in on the chemical structure of genes. Alexander Graham Bell and Elisha Gray were rivals in the development of the telephone (and indeed, Bell’s patent application preceded Gray’s by a matter of hours). 
Yet, in ordinary life, social comparisons can also be de-motivating.  To understand why, it is important to start with the core principle that people’s engagement with a task depends on two factors:  whether the goal is important for them to achieve and whether they believe they can achieve it. 
If you compare yourself to someone else who is just a little better than you are, you may be energized to improve and catch up with them.  In this case, competition increases your sense that the goal can be achieved, and provides some incentive to increase the importance of the goal.  But, if you compare yourself to someone who is significantly better than you are, you may feel like no matter how hard you work you will never measure up to their example.  Now, the gap between you and your goal seems impossible to bridge.
A paper in the March, 2016 issue of Psychological Science by Todd Rogers and Avi Feller provided evidence for the downside of competition.
In one study, they examined over 5,000 participants who were students in a Massive Open Online Course (MOOC).  Many MOOCs have the students give peer evaluations to each others’ papers in order to make the workload manageable for the instructors.  In this MOOC, students wrote a paper about mid-semester and then gave evaluations to at least three papers written by their peers.
The measure of interest was whether students finished the course and ultimately received credit for it.  The quality of essays a student evaluated affected whether they finished the course.  About 68% of students who evaluated essays of average quality finished the course.  But, only 45% of the students who evaluated excellent essays finished the class.  That is, when students read excellent examples of other student performance (and thus had a chance to compare themselves to other students who were performing well), they were less motivated to finish the class than if they read average examples of other students’ essays.
As a way of understanding the size of this effect, the researchers also looked at the effect of the grade students got on their essay.  Overall, 93% of students who got a perfect store on their essay went on to finish the class, while 75% of students who got an average score finished the class.  That means that seeing examples of excellent work (as opposed to average work) was about as demotivating to students as getting an average score on their own essay (as opposed to an excellent score).  It also means that the worse you did on your own essay, the more that you could be made to feel like you could not possibly succeed in the class.
The researchers also did a second study in which they manipulated the essays people evaluated experimentally and got similar results.
These findings demonstrate that comparing yourself to excellent performers can sap your motivation.  You have probably experienced something like this before.  When learning to play a musical instrument, hearing a real virtuoso may lead you to think you will never be any good at all.  Similarly, starting at a new gym can be an exercise in despair when you see toned gym rats go through their workout. 
That doesn’t mean that you have to fall prey to the perils of social comparison. Ask yourself why you are working toward this goal in the first place? It is rare that your goal is to be the best in the world at something, and so there is no need to be threatened by the excellent performance of another person.  If you go to the gym to get in shape, the only person you need to be better than is the person you were before you started working out.
Also, it is important to remember that anyone who is good at something has put in a lot of effort to get to that point.  When you compare yourself to others , it is easy to discount the work that it took for them to reach their current level of performance. If you do compare yourself to people who are better than you, try to imagine how good they were at the same point in their own practice.
I started playing the saxophone about 17 years ago when I was in my mid-30s.  Living in Austin, Texas, I am surrounded by great musicians. At first, I was intimidated by their ability, and hearing the number of amazing players in town made me doubt my commitment to take up the instrument.  Eventually, though, I realized that my goal was not to quit my job and play the sax, but to have an artistic outlet.  Eventually, I focused on the goal that if I played for 10 years, I wouldn’t be horrible.  Now, I enjoy hearing my peers who are more skilled than I am, because it gives me a sense of new things I might eventually learn to do.  And I did reach my goal—I now play in bands in town.

Wednesday, December 5, 2018

When fractions are better than decimals


In order to graduate from high school, people usually spend  about13 years (K-12) learning about math concepts.  One of the things that math does is to give us a universal way to think about quantities.  The beauty of the number 2, for example, is that it refers to a pair of items regardless of whether those items are bowling balls, butterflies, or beer barrels.
Even though math is about abstract concepts, the human mind is often focused on specific situations in the world.  As a result, the mathematical notations we learn may not always make it easy for us to reason about the world.  Psychologists have begun to explore the relationship between the way people naturally want to reason and ways that we can represent situations using numbers.
An interesting paper in the February, 2015 issue of the Journal of Experimental Psychology: General by Melissa DeWolf, Miriam Bassok, and Keith Holyoak explored differences in the way that fractions and decimals affect thinking. 
A fraction takes two integers and places them in a ratio (like 3/4 or 10/15).  A decimal can express the same numerical quantity, but it does so with a single number (like 0.75 or 0.66).  So, the fraction makes the relationship among numbers clear in the way it is written, while the decimal does not.
In one study, the researchers showed college students displays in which a fraction or decimal could be used as a description.  In the continuous displays, there was a rectangle and some of it was shaded red, while the rest was shaded green.  In the discrete displays, there were several objects, some of which were red, and some of which were green.  Finally, in the discretized displays, there was a rectangle (like in the continuous display), but it was divided into regions of equal size.  Some of those regions were red, and some were green.
With displays like this, there are two kinds of comparisons people can make.  There are part-to-whole comparisons. For example, if there are three red squares and five green squares, then the part-to-whole relationship of red squares is 3/8.  There are also part-to-part comparisons.  In this same display, the relationship between red squares and green squares is 3/5. 
In one study, participants were shown a continuous, discrete, or discretized display and were asked whether they would prefer to describe either a part-to-whole or part-to-part relationship for that display with a fraction or a decimal.  They weren’t asked which fraction or decimal they would use for the displays, just whether a fraction or a decimal would feel more appropriate.  For both kinds of relationships, participants preferred to use decimals for continuous displays, and to use fractions for discrete and discretized displays.  A second study asked people to identify the specific relationship shown in a display and found that people were equally good at using fractions and decimals for continuous displays, but much better at using fractions than decimals for discrete and discretized displays.
So far, these results are pretty straightforward.  The rest of the studies explored the ability to perform mathematical analogies.  In these studies, participants saw a display and either a fraction or a decimal that described the part-to-part or part-to-whole relationship in that display.  For example, if they saw 3 red squares and 5 green ones, and the fraction 3/5, that was describing the part-to-part relationship.
Next, they saw a second display of the same type, and two descriptions of the relationship.  For example, this time they might see 5 red stars and 7 green stars.  They would see one mathematical description of the part-to-part (5/7) relationship and one description of the part-to-whole relationship (5/12), and they had to pick the response that referred to the same relationship that was shown in the first display.  In this case, they would have to pick the part-to-part display.
They found that people had a hard time with this task for both fractions and decimals when the displays were continuous.  They were much better at the discrete and discretized analogies with fractions than with decimals.  This was true, even when the fractions referred to the same ratio, but did not map directly onto the number of items in the display.  For example, if the part-to-part relationship in the display with 3 red squares and five green squares was described with the fraction 6/10, that would be equivalent to 3/5, but the numbers would not map directly to the display. 
This work fits with a lot of previous research suggesting that people like to reason about frequencies of things in the world rather than proportions.  We experience the world in terms of the numbers of objects we see and the numbers of events we experience.  Math allows us to create other representations like decimals that are great for calculations, but they can make it harder to reason about what has happened in the world. 
This work also suggests that if you are staring at a numerical description of a situation and that description does not make sense to you, consider trying another way to think about it.  You are often asked to make decisions based on information that involves numbers.  Often, those numbers are decimals or proportions.  Consider turning those numbers into frequencies or fractions when reasoning about them.

Thursday, November 29, 2018

Peer Pressure Affects Your Actions More Than Your Recommendations


As a parent, I am often confronted with the hypocrisy of advice-giving.  There are plenty of things I have recommended to my kids that are courses of action that I have not taken myself.  Some of that is that I want my kids to avoid some of the mistakes I have made.  But, some of it is also that the way you give advice differs from the way you decide what to do yourself.
An interesting paper in the February, 2015 issue of the Journal of Experimental Psychology: General by Sarah Helfinstein, Jeanette Mumford, and Russ Poldrack examined an important factor that leads people’s recommendations for others to differ from what they themselves would do. 
Participants were asked about a variety of risky behaviors across a number of domains including social risks (like moving away from family), recreational risks (like bungee jumping), financial risks (like betting a day’s wages at poker), safety risks (like driving without a seatbelt) and ethical risks (like not returning a wallet with a lot money in it).  These were taken from a normed inventory called the DOSPERT.
Participants all rated the potential benefit, potential cost, and likelihood that they would incur the cost for each of these risky behaviors.  They also rated how likely it was that other people engaged in these behaviors.  Finally, participants either rated their willingness to engage in that behavior themselves or their willingness to recommend the behavior to someone else.
Overall, people were not really more or less willing to engage in risky behaviors themselves than to recommend them to others.  In some domains (like social and safety risks, people were more willing to perform the actions themselves than they were to recommend them to others.  In other domains (like recreational and financial risks) people were less wiling to perform the actions themselves than to recommend them to others.
It is the determinants of these recommendations that are most interesting.  People were more likely to perform an action and to recommend it when there was perceived benefit for doing it and less likely to perform or recommend it when there was a significant cost and when that cost was seen as being likely to happen. 
The big place where willingness to perform an action differed from the recommendations people made was in the influence of the likelihood that other people perform the action.  When recommending an action to others, the likelihood that other people perform the action did not matter much.  But, engagement of other people increased people’s willingness to perform the action themselves.  That is, people succumb to peer pressure.  When we perceive that other people are performing an action, it makes us more likely to perform it ourselves. 
This tendency is true for decisions that do not involve risk as well.  For example, studies of consumer products demonstrate that the leading brands in different product categories has remained relatively stable for a long time.  Gillette has been the leading brand of razors and Tide has been the leading brand of detergent for over 50 years.  Part of what helps brands like these to maintain their dominance is their perceived popularity.  Even without knowing it explicitly, we buy what we think other people are buying. 
When you are contemplating a decision, then, it is worth asking yourself both what you are thinking of doing as well as what you might recommend to someone else.  If you think that there is a difference between what you would do yourself and what you would recommend, then stop and think about whether you might be better off doing what you would recommend to someone else. 

Friday, September 21, 2018

Can Liars Be Caught By Aviation Security?


If you travel frequently, then you have probably endured more than one security screening interview at an airport.  At passport control, for example, border agents ask a few questions, stare at your passport, check you on electronic databases, and then send you on your way.
The purpose of these interviews, of course, is to catch people who are being deceptive.  This is a remarkably difficult job.  Thousands of people are streaming through airports every day, and only a very small fraction of them are actually being deceptive in any significant way. 
Can those few liars be caught effectively?
This question was explored in a field study by Thomas Ormerod and Coral Dando published in the February, 2015 issue of the Journal of Experimental Psychology: General. 
They trained two samples of security agents on different methods of screening for deception. 
One method focused on finding suspicious signs that are supposed to distinguish lairs from truth-tellers.  This technique, which is typical of what is taught to security screeners, involves a scripted set of questions.  As passengers answer these questions, agents look for signs of deception like nervousness or a passenger dressed inappropriately for the trip they are going on.
The other method focused on the security interview itself.  This technique uses a lot of open-ended questions designed to get the passengers to talk about themselves.  The agent asks questions of general knowledge that someone with that background should know.  For example, a passenger who claims to be a student at the University of Texas should know where the Student Union is or how to get to the airport from campus.  The technique is designed to give the passenger very little control over the direction of the interview.  Deceptive individuals like to control the conversation, so that they can focus on the details that they want to discuss.
After this training, about 200 deceptive passengers were sent through security over an 8-month period.  Notice, this means that most passengers that any agent saw were genuine passengers.  The deceptive passengers were recruited to participate in the study.  They were given payment to be in the study and a significant amount of additional money if they passed through security without being called aside for further screening.  So, the deceptive passengers had some incentive to get through security.  The ability to detect whether this group was deceptive was compared to the screeners’ likelihood of sending genuine passengers for extra screening whose demographic characteristics matched those of the experimental sample. 
A few weeks before participating in the study, the deceptive passengers were given a cover story to learn that was tailored to their age and appearance.  The example given in the paper was a male police officer who was told to imagine that he was working as an engineer near his hometown and was traveling to Chicago to take part in a fencing competition.  The deceptive passengers were told to do research to add information to their backstory.  A subset of the deceptive passengers were also given several opportunities to be deceptive at different times, to see if they could improve in their ability to fool the screeners.
The results were striking.  Screeners trained with the interview technique caught about 70% of the deceptive passengers, while those trained with the traditional method of looking for cues detected about 5% of the passengers.
You might thing this reflected that the screeners trained with the interview technique just sent more people for additional questioning than those trained in the traditional way.  That was not the case.  The agents who learned the interview technique were no more likely to send other passengers for additional screening than those who were trained in the traditional way. 
You might also think that the interview technique takes longer.  It does not.  Agents trained with each technique spent about 3 minutes with each passenger.  The big difference was that those trained with the interview technique asked more open-ended questions and gave the passengers more time to speak than those trained in the traditional way.
Finally, those passengers who were given several opportunities to get through screening were caught at about the same rate for each try.  This finding suggests that it was not straightforward for passengers to learn to beat the system. 
The reason why the system is hard to beat is straightforward.  If you claim to be someone very different from who you are, there is a wealth of life experience that you simply don’t have.  All of the specific details of life from where you shop to how you drive home to what buildings you pass on your way home are second-nature when you are telling the truth and are absent when you are involved in a large-scale deception.  These security interviews allow agents to capitalize on the absence of this knowledge when interviewing passengers.
Finally, this research is a great demonstration of the way that psychological research can be used to solve a practical problem.  First, the interview technique itself is drawn from extensive research on deception.  Second, the test itself is quite well-constructed, and the researchers do a good job of ruling out a number of alternative explanations for the results.

Wednesday, August 29, 2018

Conflicting Goals Can Make You A Better Decision Maker


We tend to think of conflict as the enemy of good decision making.  We dread situations that involve difficult choices.  Indeed, studies by Amos Tversky, Eldar Shafir, Ravi Dhar, Itamar Simonson and their colleagues suggests that people will actually avoid making decisions that are difficult.  When given a choice between selecting one of two options that require making a difficult tradeoff (for example, selecting apartments that differ in size and commute time), people prefer to put the decision off until later rather than addressing it right away.
An interesting paper by Jennifer Savary, Tali Kleiman, Ran Hassin, and Ravi Dhar in the February, 2015 issue of the Journal of Experimental Psychology: General suggests that there may also be an upside to experiencing conflict. Specifically, they suggest that when people have two conflicting goals that they are grappling with, that makes them likely to think carefully about choices in order to resolve the conflict.
In order to induce conflicting goals, participants did a lexical decision task in which they saw a series of letters and had to press one button of those letters formed a word and a second button if they did not form a word.  In the conflict condition, some of the words referred to a particular goal (such as being healthy, with words like fitness and active), and others referred to a second goal that conflicts with the first (such as indulgence, with words like decadent and indulge).  The control condition did not have conflicting goals embedded in the words that were part of the lexical decision task.  Tasks like this have been used in many previous studies to activate goals and to create goal conflict.
After this lexical decision task, one study gave people difficult choices (like a choice between apartments that differ in size and commute time) and asked people to select one of the options or to defer the choice until later.  Participants who were induced to feel a conflict between goals were actually more likely to choose one of the options rather than deferring the choice than people in the control condition who were not given a goal conflict.
In a second study, participants were given these choices using a computer system that tracked the amount of time participants spent making the decision and the number of features of the options they explored.  Participants induced to experience a conflict looked at more features and spent more time making the choices than those who did not experience a conflict.  This study also demonstrated that people were not aware of the goal conflict that was induced. 
One other study tested the idea that conflicting goals increase how thoroughly people process information about choices in a slightly different way.  Again, goal conflict was induced using the lexical decision task.  This time, though. The decision task involves selecting from among three options (say three different apartments).  One was very good on one dimension (it was large), but very bad on the other (it was far from work).  A second was bad on that first dimension (it was small), but good on the other (it was close to work).  A third was a compromise (medium in size, a moderate commute to work). 
Previous research suggest that when people don’t want to work that hard making a choice, they tend to select the compromise option so that they don’t need to figure out which dimension is more important to them.  If people really think carefully about the choice, then, they will be more likely to pick one of the extreme options rather than the compromise. 
Consistent with the other two studies, participants induced to have a goal conflict were more likely to pick one of the extreme options than people in the control condition who had no goal conflict. 
An interesting aspect of these studies is that the goal conflict that was induced was not directly related to the choices people were making.  So, the increase in depth of thought about the choices was caused by the presence of active goals that conflict, and not based on the activity of goals that were relevant to evaluating the options.
This research suggests that we experience two kinds of conflicts when making choices.  One conflict is between options that are about equally attractive and require tradeoffs among the features to figure out which is best.  These conflicts make it hard for people to choose.  Often, people prefer to defer the choice until later or pick an easy compromise option rather than resolving tradeoffs.
The second kind of conflict is one between incompatible goals.  These goal conflicts arouse the motivational system.  This arousal leads people to consider options more carefully, think about them more deeply, and ultimately helps people to make the tradeoffs that can make decisions difficult.