Monday, June 30, 2014

Are later-born children more rebellious?

There is a popular belief that the behavior of children in a family depends a lot on their birth order.  First-born children are supposed to be fairly conformist, because they do not have to compete for their parents’ attention and resources at the start of their lives.  They have a favored status that leads them to identify with authority.  Middle children have to fight hard for attention, and so they may rebel as a way of getting noticed.  This effect should be mixed for the youngest in a family.  On the one hand, they also have to compete for attention. As the youngest, however, they may get some amount of attention just for being the last child.

This idea has also been put forward within the psychology community.  For example, Frank Sulloway wrote the popular book Born to Rebel essentially making this case. 

Some data have been collected that support this idea.  In typical analyses, researchers find large-scale surveys that measure rebellious behaviors in teens (like drinking, marijuana use, and nonviolent crime) and then look to see whether birth order in families predicts the delinquent behavior.  The typical finding is that middle children are most likely to exhibit these behaviors, and first born children are least likely to display them.

The problem with these analyses is that they are typically done between families.  That is, the children all come from different families, and so it is hard to know for sure whether birth order is the true cause of the effect or whether it is some other variable like parental involvement in the family that is causing the observed relationship.

A paper in the August, 2013 issue of Personality and Social Psychology Bulletin by Patrick Cundiff found a data set that allowed him to tease apart these effects.  He analyzed the Add Health survey that was collected on school children from 1994-2008.  This survey collected information about a variety of children’s behaviors.  The survey also contained a lot of data about siblings within a family.  The survey also had information about potential confounding factors like socioeconomic status, grade point average in school, and parental involvement in the home.

Cundiff did both a between family and a within family analysis of the data.  The between family analysis used all of the children in the sample (over 14,000), while the within-family analysis used only the data from 3,800 children where the entire family was observed. 

The between-family analysis showed the same effects as previous research.  This analysis found that middle children were about 33% more likely to exhibit delinquent behaviors than firstborn children.  Last born children were about 20% more likely to exhibit these behaviors than firstborn children.  Examination of a variety of aspects of the children like grade point average and aspects of families like parental closeness did not eliminate the effect of birth order.

However, when the data set looked only within families, the relationship between birth order and delinquent behavior was sharply reduced in size and was no long statistically significant.  In this analysis, only gender and parental involvement had a reliable effect on behavior.  That is, boys were more likely to engage in delinquent behavior than girls, and children with a low level of parental involvement were more likely to engage in delinquent behavior than children with a high level of parental involvement.

This paper is consistent with a growing body of evidence suggesting that there are few reliable effects of birth order on children’s behavior. Thus, while it is intuitively reasonable to think that firstborn and later-born children differ, it does not look like that is really happening.

Monday, June 23, 2014

What do young kids know about animals and objects?

The world is made up of many different kinds of things, and in order to get around the world successfully, we have to learn both about the individual items we encounter and we also need to learn information that will help us to deal with new things.  So, when you learn that a particular object in your world is a chair, you need to know what to do with it, but you also need to pick up bits of knowledge that will be of value when you learn about other objects, like tables, lamps, or ovens.

When you look at what adults know about the world, there is a big difference in the way they think about artifacts and animals.  Artifacts are human-made objects that are designed for some purpose, while animals are the result of an evolutionary process. 

Generally speaking, the artifacts of a particular type vary a lot more than animals of a type.  Any given chair might have legs, or it might have a pedestal.  It may be made of many different kinds of materials.  It may have many different colors.  The fact that something is a chair tells us a little about it (like it was made for sitting on), but not much else.

In contrast, different animals of a type are all fairly similar.  Cats, for example, have four legs, are furry, have similar internal organs, and behave in similar ways. 

Adults recognize that animals and artifacts differ in this way.

At what age do people learn about this difference between animals and artifacts? 

The difficulty with answering this question definitively is that young kids often have trouble telling us what they know.  As a result, it is useful to have more indirect ways of teasing apart what they know.

A clever study by Amanda Brandone and Susan Gelman in the January 2013 issue of Cognitive Development examined the way kids talk about animals and artifacts as a way of assessing what they know about these kinds of things.  In particular, they focused on generic language.  A generic statement is one that is meant to apply to (nearly) all of the objects being described.  If someone says, “Chairs are made for sitting in,” she means this sentence to apply to (nearly) all chairs.  If she says “Cats meow,” then she means to describe (nearly) all cats.  If children know that animals generally have more in common than objects, then we would expect children to use generic language more often when talking about animals than when talking about objects.

In this study, five-year-olds were shown a set of drawings of things that they were told came from an alien planet. Some children were shown the pictures and were told that they were kinds of artifacts (like machines, vehicles, and tools).  Other children were shown the same pictures and were told that they were alien animals.  Each object was given a novel category name.  So, a child might be told that a particular object was a “dax.”  The novel category name was used so that children could only use general knowledge about things to understand the new object.

At the start of the study, children were introduced to a puppet that they were told was blind.  After seeing each picture, they were asked to tell the puppet about the object.  A group of adults were shown the same objects and were also asked to describe them.

The experimenters analyzed the language that the children and adults used to describe the objects.  In particular, they were interested in how often children and adults used generic statements to describe artifacts and animals.

Both the adults and the children used generic statements more often when describing animals than when describing artifacts.  That means that even pre-school children know that animals of a particular kind have more in common with each other than artifacts of a particular kind.  When adults and children used non-generic language, they used it about equally often for the artifacts and the animals.  So, it is not just that people wanted to talk more about the animals than about the artifacts.

These expectations about objects and animals guide the way children learn about new things.  Because children expect animals of a particular type to have lots of similarities, they look for those similarities when they encounter a new animal.  When children encounter an artifact, though, they spend more time exploring the function of the artifact than the properties. 

Wednesday, June 11, 2014

I want what is best for you, but what is most possible for me.

At the end of a long week, we often order takeout food from a local restaurant rather than cooking.  There are a lot of restaurants in Austin, and many of them serve really excellent food.  Yet, we tend to order from the same small list of places.  There are better restaurants, but by the time we get down to ordering, we are most interested in doing what is easiest.  The places we normally pick are within a few minutes’ drive of the house.

This example rests on two factors that influence a lot of our choices:  desirability and feasibility.  Desirability is how much we want a particular option.  Feasibility reflects how easy it is to get that option or how likely we are to succeed if we make a particular choice. 

An interesting paper by Jingyi Lu, Xiaofei Xie, and Jingzhe Xu in the February, 2013 issue of Personality and Social Psychology Bulletin explored how we trade off between these concerns.  They suggest that people pay more attention to feasibility information when making a choice for themselves than when making a choice for someone else.

In previous blog entries, I have talked about an observation that came from research by Yaacov Trope and Nira Liberman that we tend to think about things more specifically when they are psychologically nearer to us than when they are psychologically distant.  In the case of decisions, making a choice for yourself puts you psychologically closer to that choice than making a choice for someone else.  When you think specifically about a choice, you generally focus on the specific circumstance you are in.  So, you are concerned about whether the option is feasible. When you think generally abstractly about a choice, you focus on more general concerns like whether the option is going to be enjoyable.

To test this proposal, the researchers did several studies. In one experiment, college students could choose to purchase coupons for restaurants.  Some participants selected restaurants for themselves, while others were asked how much a typical student would be willing to pay for these coupons.  One restaurant was described as having excellent food and being very popular, but also being far away and often crowded so that there is a wait to get a table.  The other was described as having decent food, but being close by without long waits to get a table.  When choosing for themselves, people were willing to pay more for the nearby restaurant than for the restaurant with good food.  When choosing for a typical other person, people were willing to pay more for the restaurant with good food than for the restaurant that was close by.

A second study examined the kind of information people seek when making choices.  In this experiment, the materials were descriptions of classes.  People were asked to choose a course either for themselves or for a typical student.   Each option was described by 10 features.  Five of those were related to how desirable a class was likely to be (like how interesting it is or how much depth it covers).  Five were related to how easy it would be to complete the class successfully (like passing rate and difficulty of the assignments).  People had to select which five features they wanted to see.  Participants choosing for themselves were more likely to select information about how easy the class would be to complete than people who were choosing for a typical student.

A third set of studies had people make choices and then later asked them what they remembered about the options.  In this study, people making choices for someone else remembered more about how desirable the options were than those who were making choices for themselves. 

Putting all of this together, we treat choices differently depending on whether we are making a decision for ourselves or for someone else.  When we choose for ourselves, we are mentally nearer to the decision than when we are choosing for someone else.   As a result, when choosing for ourselves, we focus on information that is related to the ease of the options, but when choosing for someone else we focus on the desirability of the options.

If you find yourself opting for the easy choice, then, you can get yourself out of that rut by imagining what someone else would do in the same situation.  That can get you to think more about picking will be most enjoyable for you.

Thursday, June 5, 2014

Oxytocin and conformity

Oxytocin has been the focus of a lot of research lately.  Oxytocin is a hormone that is released when people touch or kiss.  It is also released during orgasm, during childbirth, and during breastfeeding.  In the body, oxytocin creates muscle contractions and it also plays a role in the reflex that causes milk to be let down in nursing mothers.  Oxytocin also acts on the brain, and that has been the source of a lot of research.  Various popular accounts have called oxytocin a trust chemical or a love chemical.

The reality is more complex.  A nice demonstration of this complexity comes from a study in the December, 2012 issue of Psychological Science by Mirre Stallen, Carsten De Dreu, Shaul Shalvi, Ale Smidts, and Alan Sanfey.  These researchers focused on the influence of oxytocin on people’s preferences for new objects.

Groups of six participants were brought to the lab where they were administered oxytocin or a placebo using a nasal spray.  Participants were each seated in front of a computer, and they did about 40 minutes of filler tasks to allow the oxytocin to have its effect.  Then, participants were informed that the group was divided into two teams.  Each participant saw a series of novel icons and were asked to rate how much they liked them.  At the bottom of the screen, they could see ratings that they believed were given by other participants.  (In fact, the ratings were generated by the experimenters.)  They could see whether the ratings came from members of their team or members of the other team.

If oxytocin just increases overall trust, then we would expect that people who are given oxytocin would give preference ratings that are more similar to the other ratings of all of the participants.  However, the researchers suggested that oxytocin may have a more specific effect.  It might increase people’s tendency to conform to the ideals of other members of their own social group.  In that case, we would expect that people’s ratings would track those of other members of the same team.

To provide a critical test of this possibility, on a certain number of trials, the icons got divergent ratings from the participant’s team members and the other team.  Sometimes the team members gave the icon a high preference rating while the other team gave it low ratings and sometimes the opposite occurred. 

On these trials, participants who got the placebo were relatively uninfluenced by ratings of their team members.  However, the participants who got oxytocin gave significantly higher ratings when their team members also gave the icon a high rating than when they gave it a low rating. 

This result suggests that oxytocin increases people’s sense of closeness to their social group (even when that social group is arbitrarily created in the lab).  This closeness leads people to generate attitudes that conform to those of their group members.  However, it does not increase general trust of all people.  The attitudes of people from other groups do not influence their behavior.