Wednesday, April 27, 2016

People Differ in Their Ability to Suppress Memories

Your ability to recall a word or event involves mechanisms that enhance the item you want to remember and suppress competitors.  It is like a bunch of 6-year-olds trying to be picked for the kickball team.  The kids who jump the highest and shove the other kids hardest are the ones who are selected.

Psychologists use the word inhibition to refer to the suppression of items in memory.  The inhibitory mechanisms in the brain involve circuits in the frontal lobes.  

A fascinating observation over the past decade is that these inhibitory mechanisms in the brain can cause subtle variability in people’s heart rate through the vagus nerve.  If you measure someone’s resting heart rate and measure the amount of variability in the time between beats, that variation may serve as a marker of the strength of people’s ability to inhibit information in memory.

An interesting paper by Brandon Gillie, Michael Vasey, and Julian Thayer in the February, 2014 issue of Psychological Science explored this possibility.  

They used a memory test called the Think/No Think procedure first developed by Michael Anderson and his colleagues.  In this procedure, people learn a list of associations between words.  The list might include items like “tape-radio.” 

After practicing these associations 3 times, the Think/No Think procedure begins.  The first word of a pair (tape) is presented in green or red (or is not presented at all).  If it is presented in green, then people are instructed to think about the associated word for 4 seconds.  If it is presented in red, then people are instructed to avoid thinking about the associated word for those 4 seconds.  This procedure is repeated 16 times, so that people get a lot of practice either thinking about the association or not thinking about it.  

There are two tests of recall.  People see the first word of the pair and are asked to recall the second.  In a second test, they see the first word of the pair and the first letter of the second word and are asked to recall the second word. 

Finally, all participants had their heart rate collected using an electrocardiogram (ECG).  The ECG output was analyzed to determine the variability from beat-to-beat.

The standard finding with this procedure (which is also obtained in this study) is that (on average) people recall about 10% more of the associations when they see them in the Think condition than in the No Think condition.   

The group of participants was split into one group with relatively high variability in heart rate and a second group with relatively low variability in heart rate. 

Having low heart rate variability is associated with having low inhibitory control in memory.  That group showed very little difference between the Think and No Think conditions of the study.  They remembered the associated words equally well regardless of whether they were instructed to think about them or not to think about them.

Having high heart rate variability is associated with high inhibitory control.  That group showed a big difference between the Think and No Think conditions.  They remembered many more words when they were encouraged to think about them than when they were encouraged not to think about them.

The ability to inhibit unwanted items in memory is valuable.  Research suggests that this ability degrades with age, which is one reason why older adults often have trouble with memory.  So, having a physiological measurement that relates to this degree of inhibitory control is useful.
As valuable as the ability to inhibit information can be, it is important to recognize that the No Think condition does not eliminate people’s ability to recall the associated words.  Creativity requires being able to think about information that does not seem obviously related to the current situation.  Juxtaposing different information sources is a great way to look for a novel solution to a problem.  As a result, we want to have good inhibitory mechanisms, but not ones that work too well.

Monday, April 18, 2016

Beliefs About Time Affect Savings

It is hard to save money, because we are wired to prefer to do things that are good for us in the short-term over those that are good for us in the long-term.  No matter how much we believe that our future self might want to buy a nice car, send our kids to college, or eat after we retire, there are always shiny things that we would like to buy right now that seem to have a priority over our future.  

So, how can we help people to save more money?

A fascinating paper by Leon Tam and Utpal Dholakia in the February, 2014 issue of Psychological Science suggests that people’s beliefs about time may have a big impact on how much they save.

The dominant way that many people (particularly from Western cultures) tend to think about time is as a line.  Individuals occupy a point on that line that is the present.  Behind them is the past, and ahead of them is the future.  Because the future is far away, many approaches to help people save more money are designed to make people feel like the future is nearer to the present than it seems.  The idea is that when people realize that they have to help our future selves, they will be more likely to put away money to help them achieve their future goals.

These techniques often fail, however.  People recognize that their future selves may need help, but they are also optimistic that they will be making more money in the future and so they will be in a better position to save money later than they are now.

Tam and Dholakia point out that people also think about time in terms of cycles.  People know that the days of the week repeat, and that the seasons come each year.  When people focus on these cycles, they may realize that their lives don’t change much from cycle to cycle.  Consequently, if people don’t save money now, why should they believe that they will be in a different situation the next time this cycle happens?  The researchers argue that getting people to focus on the cyclic nature of time may get people to increase the amount they save, because they realize that the future will not be that much different than the present.

In one study, adults between the ages of 19 and 55 were placed in one of three experimental conditions.  

One group was told to think about time as a cycle and to recognize that life’s cycles repeat themselves.  They were told that if they do not save money now, they are unlikely to be in a different situation the next time this cycle came around.

A second group was told to think about time as a line.  Their goal was to save money to put their future selves in a better position to achieve their goals.  

A third group got no specific instructions about time.

Then, the participants predicted how much money they would save over the next two weeks.  Participants were then contacted after two weeks and stated how much they had saved in that period.

Participants in the control condition predicted they would save $133, and actually saved $81.  Those told to think about time as a line did not do much better.  They predicted they would save $140, and actually saved $118.  The group given instructions to think about time as a cycle did much better.  They predicted they would save $233 and they actually saved $216.  

Another study by these authors extended the work in two ways.  First, participants were either told to think of time as a line or as a cycle.  They made predictions both for how much they would save this month and also how much they would save a year from now.  Participants told to think of time as a cycle predicted they would save more this month than those who were told to think of time as line.  This replicates the previous study.  However, those told to think of time as a line predicted they would save more money a year from now than those who were told to think of time as a cycle.  That is, participants who thought of time as a line were more optimistic about their future ability to save money than those who thought of time as a cycle.  

Finally, everyone was asked questions about their ability to make plans to save money.  The participants asked to think about time as a cycle exhibited more confidence in their plan to save money than those asked to think about time as a line.

What does all of this mean?

We are often optimistic about what the future holds.  In the future, we believe that we will make more money, be better at resisting temptation; we assume we will eat better and exercise more often.  In reality, though, the future is typically much like the present.  There are always temptations to spend money, eat too much and skip exercise.

Focusing on the cycles of life helps people to be more realistic that the future will be like the present.   Achieving future goals requires acting now. 

Wednesday, April 13, 2016

Young Infants Learn By Doing

The brain is an extraordinarily complex organ that we are struggling to understand scientifically. To help us understand the way the brain works, we often use the most complex machines of an era to give us insight into what the brain is doing.  And starting in the 1950’s, the most complex machine we had was the computer.  

One influence of this computer metaphor for the mind is that it has emphasized the information that is processed in the brain over the relationship between mind and body.  After all, computers have poor bodies.  They have a keyboard and mouse as a sensory system and a display and internet connection as ways of acting on the world around it.  As a result, most research in psychology focuses on how the brain processes particular kinds of information without much focus on how the body influences that thought.

There are some streams of research that buck this trend.  In research on adults, there is work on situated cognition that explores how the environment affects the way people think.  There are also studies in embodied cognition that examine how body and mind interact.

Over the years, there has also been work on how the body influences learning in infants and children.  In my last blog entry, for example,  I talked about how experience moving influences children’s curiosity about heights.

A fascinating paper in the February, 2014 issue of Child Development by Sarah Gerson and Amanda Woodward examines how 3-month-olds learn about other people’s goals from their own actions.

If you have ever spent any time with a 3-month-old, then you know that they are not particularly coordinated.  Jessica Sommerville, Amanda Woodward, and Amy Needham developed an ingenious method for looking at actions in 3-month-olds (reported in a paper in the journal Cognition in 2005).  They attached mittens with Velcro on them to infants’ hands.  Then, the infants could reach out and move toys that also had Velcro on them.

In Gerson and Woodward’s study, all of the infants had a chance to sit with the toys for a few minutes without the mittens.  Then, some infants had the mittens put on, and they reached out and played with the toys for a few minutes.  For these infants, playing with the toy generally meant moving it back-and forth across the table.  A second group of infants was matched with the infants from the first group.  For each infant in the second group, the experimenter mimicked the actions of the infant using Velcro gloves, so that this infant got to watch something similar to what the first infant did.  That provides a control condition in which the infants are exposed to the actions without actually performing the actions themselves.

After this initial exposure, infants were tested.  It is hard to test 3-month-olds, because they cannot speak or understand much language.  Instead, researchers typically use a looking procedure.  

In this study, the two toys that were used in the first part of the study were placed on a stage.  A gloved hand reached out and picked up one of the toys.  This event was presented several times until the infants stopped looking at it.  This decrease in looking time is called habituation and is used as a measure that the children can predict what is going to happen.

Then, the positions of the two toys were switched.  So, the one on the left is now on the right and vice versa.  Now, two types of test trials were given.  In one type of test trial, the hand reached out and grabbed the toy that was now on the left.  In this case, the hand performed the same action, but the outcome was different.  In the other type of test trial, the hand picked the same object that it selected before.  In this case, the movement was different (because the hand had to reach all the way to the right), but the outcome was the same (because the same object that was touched earlier was selected again).  

The experimenters measured how long infants looked at each type of test.  The longer infants look, the more interested they are in that outcome, generally because that outcome is different from what they expected.

The infants who watched someone else acting on the toys did not look reliably longer at either type of event. Those infants who acted on the toys themselves looked for a longer time at the event with a different outcome than at the event with the same outcome.  That is, by playing with the toys, infants seemed to learn that other people often direct their actions at particular outcomes rather than just making particular movements.

The infants learned something very specific from this experience, though.  A third group of infants played with the toys using the mittens, but then the test trials involved a different set of toys than the ones they played with.  This group also did not look reliably longer at either type of test event.  That is, the infants learned only about outcomes involving the specific toys they played with.

What does all of this mean?

One way that infants learn about what other people want to do is by learning about how they perform actions in the world.  As they learn that their actions can be directed toward particular outcomes, they also learn that other people may act to bring about particular outcomes.    

However, it also appears that this learning is very conservative.  That is, infants start by learning about their interactions with particular objects.  It is valuable to keep from generalizing too far from early experience, because there are likely to be many exceptions to the early rules that infants learn.

More broadly, this research demonstrates the importance of acting on the world when learning.  Too often, even adults try to learn passively by listening to others and reading superficially.  It is important to engage with the world when learning rather than just treating the process of learning as if we were computers that were being fed information.

Monday, April 4, 2016

Are Infants Afraid of Heights?

When I was in college, I worked at a lumberyard.  One day, the boss asked me to climb to the second level of a storage barn at the back of the property and do an inventory on the 4’ by 8’ sheets of paneling in bins at the top of the barn.  There was a one foot ledge in front of each bin, and so I had to sit on that ledge, about 10 feet off the ground, and lift each sheet of paneling in the bin to count them all.  After the second bin, I slid over to the ladder, climbed down, and gave up.  I was simply too scared of the drop to continue.

When do people become afraid of heights?

This question was discussed in a paper in the February, 2014 issue of Current Directions in Psychological Science by Karen Adolph, Kari Kretch, and Vanessa LoBue. 

If you are familiar with research in developmental psychology, then the answer might seem obvious.  In the 1960s, there was a lot of research done on the visual cliff, which was developed by Eleanor Gibson and her colleagues.  The visual cliff involves a ledge with a checkerboard pattern.  There is glass at the dropoff of the ledge, so that infants see the cliff, but do would not be hurt by stepping onto it.  Infants who have first learned to crawl climb right out onto the cliff.  Those with a few weeks of movement experience stop at the edge.

It seems straightforward to say that the infants stop at the edge, because they are afraid of falling.  And for years, that was the standard way of talking about infants’ performance on the visual cliff.

The problem is that infants don’t really display a true fear reaction when they get to the edge of the cliff.  They don’t climb out onto it, but they do spend a lot of time peering over the edge.  They reach out and explore the space.  They do not display fear on their faces.  They do not cling to their parents. 

Infants of that age can display fear.  For example, when infants of that age are approached by strangers, they do cling to a familiar adult, have an increase in heart rate, and have facial expressions and make noises that are fearful.  So, infants can feel fear, they just don’t seem to exhibit that fear to the cliff.

Instead, infants quickly discover that heights create situations in which something can be learned.  For example, infants learn about ramps and stairs.   Over time, they learn which stairs can be climbed up and down and which are too high.  They learn what kinds of ramps are too steep to climb down.  Work by Karen Adolph and her colleagues even demonstrates that infants react differently to ramps depending on whether they are wearing a vest with lead weights in it (which makes a ramp harder to descend) or with feathers in it (which has little effect on their movements). 
Early on, then, infants are curious about heights, but not fearful.  They recognize that they should not immediately dive over a cliff, but they also spend time in that environment trying to learn what they can and cannot do. 

Eventually, of course, many children do display some fear of heights.  Some children may fall and learn their fear in that way.  However, just watching someone else fall or even something else fall from a height may be enough to help children realize the dangers of falling from heights.  But, this fear does not kick in until after children have had some opportunity to explore their environment.