Monday, October 30, 2017

Children Decide Who They Should Learn From Based On Experience


Another theme in this blog has been the way children learn to learn. Humans are able to survive in almost any environment in large part because we are able to learn so effectively from other people.  Each generation adapts to the culture and technology of the time.  Although this process takes a lot of time compared to other animals, it supports our ability to create cultures of ever-increasing complexity. 
Of course, not every other person is one that a child should learn from.  Some people know quite a bit about what is going on in the world around them, while others provide unreliable information.  If children get bad information early on, that could hurt their ability to learn more complicated things later.
So, it would be valuable for children to be able to determine the best people to learn from.  A paper by Kathleen Corriveau and Katelyn Kurkel in the October, 2014 issue of Child Development examined whether children can use the quality of the explanations people give to determine who they should learn from.
They studied 3- and 5-year-old children.  In one experiment, the children were introduced to two girls.  The girls each gave short explanations for how the world works.  One girl always gave good explanations, while the other one gave circular explanations.  A circular explanation is one that involves the phenomenon itself in the explanation.  For example, the good explanation for why rain falls is “It rains because the clouds fill with water and get too heavy.”  The circular explanation was “It rains because water falls from the sky and gets us wet.” 
After getting these explanations, the children heard explanations for novel objects given by each girl.  They also heard labels for novel objects given by each girl.  In these tasks, the explanations and names were equally good.  So, the question is whether children were biased to agree with the girl who gave the better explanations earlier in the study. 
The five-year-olds were strongly biased to listen to the girl who gave the better explanations.  They agreed with the explanation for the new object given by the girl who gave good explanations.  They also used the label given by that girl rather than the label given by the girl who gave circular explanations.  The three-year olds were influenced, but to a lesser degree.  They accepted the explanation given by the girl who gave good explanations before, but they did not show a bias to use the labels she gave.
The five-year-olds were also better able to say explicitly that the girl who gave good explanations was a better explainer than the girl who gave circular explanations.  The three-year-olds were not able to make this judgment.
This study suggests that by the time children are five years old, they are able to make good judgments about what people they should learn from.  They use the quality of the explanations people give them to determine who is a reliable teacher.  And, they use this knowledge to influence a variety of things they learn from them.  At the age of three, children can do this to some extent, but they are still learning how to judge which people are good teachers.
This ability is crucial, because it helps children to avoid bad knowledge.  Human memory does not allow us to erase facts that turn out to be false.  Instead, when we learn that something is false, we have to mark it as being untrue so that we explicitly ignore it later.  That is one reason why we often continue to be influenced by information that we have been told in the past was not true.  Ultimately, the better the quality of the information we can learn, the fewer memories that we will have to explicitly ignore in the future.

Monday, October 16, 2017

Are Teens Really Prone to Take Risks?


If you read the local news section of a newspaper, you are bound to come across the story of a tragic death or injury to a teen.  They might be texting, drinking and driving, or skateboarding in a precarious spot.  Reading these stories may reinforce a general belief that teens simply take too many risks.
So, are teens really bigger risk-takers than adults?
A fascinating paper by Erik de Water, Antonius Cillessen, and Anouk Scheres in the October, 2014 issue of Child Development examines this question.
A lot of the behaviors in teens that we think of as risky are really impulsive.  Being impulsive means doing something that feels good right now rather than waiting in order to do something even better in the future. 
There are two parts to impulsivity.
The first is risk.  When you are impulsive, you might choose to do riskier things now without thinking through the long-term consequences.
The second is value.  If you value things in the present more than things in the future, then you may choose to get things right now.  Everyone values the present more than the future to some degree.  I would rather get $10 right now than to get $10 in a week.  But, how much more would I need to get in a week in order to forego $10 right now.  I might still prefer $10 now to $10.01 in a week.  But, perhaps I would take $12 next week rather than $10 today. 
These researchers tested teens ranging in age from 12-17 and young adults ranging in age from 18-27.  All participants were given a test of risk and a test of value.  They were also given a test of fluid intelligence (the Raven’s Progressive Matrices test) and a test of how much they value different amounts of money right now. 
The test they used to measure risk was a simple gambling task.  Participants saw a pie cut into 6 pieces, where 4 pieces were in one color and 2 were in the other.  This pie represented a gamble in which there was a 2/3 chance of winning one prize and a 1/3 chance of winning the other.  The prizes were set up so that the prize with the higher probability was always half the size of the prize with the lower probability.  So, a gamble might offer a 2/3 chance of winning $4 and a 1/3 chance of winning $8.  The more often someone selects the low probability gamble, the more risk they are taking.
The test for value involved having people make a series of decisions about whether they would prefer a particular amount of money right now or a larger amount of money some time in the future.  The time period ranged from 2 days to a year. 
The results suggested that teens were not riskier than adults, but they did value the present more than the adults did.  That is, both adults and teens selected the riskier gamble at about the same rate.  However, compared to the adults, teens needed more money in the future to be willing to delay getting money now rather than money later.  Other measures in this study examined how much teens value particular amounts of money.  Teens definitely find small amounts of money to be more valuable than adults.  But, even taking that difference into account, teens still valued money in the present more than money in the future.
What does this mean?
We tend to think of teens as taking more risks than adults.  But, findings like this suggest that teens are more impulsive not because they are willing to take more risks, but because they value the present so highly.  The difficult thing for teens is to recognize that future experiences may be more valuable than their options in the moment. 
It is important to tease apart these factors, because it influences the kinds of information we want to give to teens to help them take a long-term perspective on life events.  If teens were big risk takers, then we might want to educate them better about the risks associated with behaviors.
But, because teens value the present so strongly, it is important to help them see the value of the future.  One reason for the viral success of the “It Gets Better” videos is that it aimed to help LGBT teens to see that the problems that they face now are not as big as they seem and that the future holds valuable things in store.  This strategy is one that can be generally effective in helping teens to delay impulsive behavior right now in favor of the long term.

Wednesday, October 11, 2017

Sleep and False Memories


When you remember a past event, you are not just playing back a video or audio file of a previous encounter.  Instead, memories are reconstructed.  That means that many sources of information can be combined to influence what you remember about the past.
Most of the time, of course, that is a good thing.  When you are having a discussion about World War II, for example, it does not matter if the information about the war that you talk about came from a single lecture you attended or from years of classes and books you read.  What is important is just that the information is organized around the topic of discussion.
Of course, the specific events and the order of those events do matter a lot in eyewitness situations.  However, quite a bit of research demonstrates that eyewitness accounts are also reconstructed, and the means that information encountered after the initial event can influence later memory.
Does the amount of sleep you get affect how likely it is that you will mix together different sources of information when thinking about an eyewitness event?  This question was explored in a paper by Steven Frenda, Lawrence Patihis, Elizabeth Loftus, Holly Lewis, and Kimberly Fenn in the September, 2014 issue of Psychological Science.
They used a typical misinformation procedure in this study.  First, participants saw a sequence of photographs of two crimes (a car break-in and a thief stealing a woman’s wallet). At some point after seeing the photo sequences, participants read text stories that described the events in the photographs.  However, three of the facts in the story differed from what was shown in the photos.  For example, a photo might show the thief putting the stolen wallet in a jacket pocket, while the story might describe him putting it in his pants pocket.  About 20 minutes after reading the text, participants then got a test about the event.  The critical questions on this test focused on the misinformation parts of the event.  The key measure is whether participants recall what happened in the photograph or whether they use the information from the text of the story to answer the question.  For each question on the test, participants were also asked the reason for their response.  The strictest measure of a false memory is when participants choose the information they read in the story, but tell state that they saw it in the picture.
To explore the influence of sleep deprivation, some participants were kept awake for a full night, while others were allowed to sleep as much as they wanted.   Half the participants saw the pictures in the morning followed by the stories with the misinformation about 40 minutes later.  The other half the participants saw the pictures followed by the misinformation in the morning.
When participants see the pictures in the morning and then the misinformation soon after, sleep deprivation influences their tendency to have false memories.  The sleep deprived participants remember more of the misinformation than the rested participants.
When participants see the pictures the evening before seeing the misinformation, though, sleep deprivation has no reliable impact on false memories.  The likelihood of incorporating information from the stories in their recall is low for all participants who saw the photos the night before.
What is going on here?
Think about how people could respond accurately on this test.  When they encounter the initial event, they have to remember both what they saw as well as when they saw it.  That is, they have to keep track of the source of the memory.  That way, when they read about the event later, they can separate what they saw from what they read.
People who are sleep deprived seem to have more trouble than those who are rested keeping track of the source of the information they get.  They are able to remember facts about the events, but they are more likely to combine together different sources of information.
This result suggests that we might want to be careful about how much we trust the details of memories of events that happened when we were sleep deprived.  The lack of sleep may make it difficult for us to remember the source of the information we have encountered.