Friday, November 30, 2012

Personality Testing

Last night, a friend asked me about the Myers Briggs personality test. This morning, I just got an email from my workplace's Staff College inviting me to attend a session on Myers Briggs personality testing.

The Myers-Briggs Type Inventory is obsolete. It was derived from one person's theory, not data. It had some use in the past, and it for a long time it was the best thing we had, but we have better methods of measuring personality now. Using this system today is like using a Model T car or an Apple II computer.

The proper way to measure personality is to use the Big Five personality traits of Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism (OCEAN). These traits were found by analyzing lots of data with advanced statistical techniques. They are reliable, robust, and valid, and have been shown to correspond with a wide variety of important life outcomes. All social scientists who do real work with human personality traits have known this for over a decade.

There is not much else to say about that, but this is a good opportunity to point out a potential problem with how people think about personalities. The human mind instinctively wants to put things in groups or categories. This is a relic of our paleolithic past where it was very important for a brain to instantly and accurately put something in the category of 'snake' or 'vine'.

But the categorization instinct often leads to mistakes in the modern world, and it definitely leads to mistakes when applied to personality traits. All personality traits that can be measured fall on a continuous scale, and most of them have the 'bell curve' pattern where most people are in the middle of the scale and it is rare for people to be extreme.

This means that it is a mistake to try to classify everyone as an introvert or extrovert in the same way that it is a mistake to classify everyone as smart or dumb. Most people have an average level of intelligence and extraversion and other traits. Differences between people are differences of degree, not kind.

If you must impose categories, then you should not use the two categories of intovert and extrovert. You should use the three categories of introvert, normal, and extrovert, where people only get classified as introvert and extrovert if they are far enough from the average.

Thursday, November 15, 2012


The memories of most humans are constantly changing. The proper metaphor for memory is not a printed book. It is more like a website that is constantly being added to and edited, often with old irrelevant bits being deleted.
People do not actually remember every detail of their lives. They know an overall narrative, the setting, and the characters. When reminded of a specific event, they reconstruct the memory from those bits like a theater company creating a scene from a play.
Updating memories based on the facts you observe in the world is a proper and healthy thing to do, because human memory is much less reliable than observation of the facts of the world. If your memory disagrees with the facts, then the thing at fault is probably your memory. But this process can be used too often, and manipulated. People construct their memories to fit the narratives of their life. Often, memories are constructed or edited to fit in with social norms. 
For example, if you ask people in a survey about their level of education, reported education levels are much higher than the actual education rates of the time period. This is not due to the lesser educated people dying off, and we do not think that people are deliberately lying. People seem to make honest mistakes, updating memories about the facts of their lives to match current conditions. Consider someone had a couple years of college in the 50's, and then got a good job. Nowadays, people know that it is impossible to get such a job without a full four-year degree. The person being interviewed knows that he went to college, knows that he got a job that requires a college degree, concludes that he must have received a college degree, and therefore remembers that he has one.
Similarly, very few people will report voting for a politician that turned out to be bad. They know that they would not vote for him today, and so they conclude that they must not have voted for him in the past.
I have one memory that I know to be a false reconstruction. There is an important scene in Lord of the Rings where Frodo offers the One Ring to Galadriel, and she responds by describing what she would be become if she took the ring. In the book, she says she would become "as beautiful and terrible as the morning and the night". In the movie, this was changed to "beautiful and terrible as the dawn."
I remember watching the movie and seeing Galadriel say "the morning and the night". I remember her face and the intonation of her voice as she said it. But she never said it. My brain reconstructed the dialogue based on the text of the book, filling in the face and voice. Watching the movie again did not erase this memory. It simply created a new memory of her saying 'the dawn'. I have both memories, as if I watched two different cuts of the movie.
In general, however, my mind does not do this nearly as much as most people. My brain usually does not reconstruct memories. This means that the memories I have tend to be more accurate than the memories of most people, but I have a lot fewer of them.
I have very few memories of my childhood, even relatively recent events. Almost all of elementary school and middle school is simply gone. It was a big surprise to me when I realized that most normal people remember the names of most of their elementary school teachers. The only reason I know any of their names is that I remember my parents talking about them, years later.
'Blur' would be the wrong word; the memories are simply gone or were never formed. I remember just a few events from each year, at most. Even vast sections of my recent life are lost to me. I kept random notes of various things when I worked at a lab supply company before going to grad school. As I was looking through some of these recently, I read several descriptions of events that I have no memory of now. They were important events at the time, involving miscommunication, mistakes, office politics, and other high drama, but they are completely gone from my memory. It is like reading an account of someone else's life. I think that most people's minds would reconstruct a memory based on the description and memories of the people involved, but mine does not.
I am far more likely than most people to respond to a question about my life with "I don't know." or "I don't remember." This often surprises my friends and family. It seems especially surprising when asked about my desires or preferences. My friend recently asked me if I liked a brand of cider more than a different brand I had drunk last week. I could not answer the question, because I did not have a sufficiently detailed memory of the last week's cider. They were both simply 'good' and any comparison was impossible because my memory did not have the detail needed to support one. I think that most people would have reconstructed a memory in order to make the comparison, but my brain does not work like that.
My brain simply does not see fit to record most of the things that happen to me, and does not reconstruct memories about them when prompted. Instead, it remembers scientific and historical facts and constructs theories and connections about those facts when prompted. I would not want to have the memory system of a normal person. But I suspect that most normal people would not want to have my memory system.

Wednesday, November 14, 2012


My office is next to a metro stop, so when I visit my friends in Virginia I leave my car in our parking lot, take the metro there and back, and then walk from the metro to my car. This means walking past my office building and through a landscaped area with a pond and wetland area next to a creek.
It was about midnight last night when I got off the metro. As I was walking to my car in the dark, I saw something that looked very much like a rat the size of a mastiff. My limbic system dumped an impressive amount of adrenaline into my body before my prefrontal cortex realized that it was a beaver.
The beaver shuffled quickly away from me and into the lake. I am fairly certain that it lives there. It may be my imagination, but it seems that the water level of the lake is higher than it was a few months ago. There is a culvert separating the lake from the creek, and as I came to work this morning I noticed that the water level on one side of the culvert was significantly higher than on the other side. Beavers love to make dams by stuffing things in culverts. It is probably living in a burrow dug in the bank of the lake.
I do not think I want to tell anyone here that there is a beaver living between us and our parking lot. They might freak out and try to have it removed.
People around here get really wierd about animals. Our office sometimes has mice coming in when it gets cold.  A few weeks ago, one ran past the office of one of the other economists. She has run marathons, and she always seemed to be a strong, capable, no-nonsense feminist. But when she saw the mouse, she yelled for me, and when I came out of my office she had a frightened look on her face and her hands in front of her chest in a stereotypical scared-weak-woman pose right from a 50's sitcom.
And then there was the time when I saw a mouse run into the office of one of the lawyers. She left and refused to go back in for the rest of the day. I had to get her lunch out of her office for her.
Not long after I moved into my apartment, I saw a mouse run into my living room closet. I still had my moving boxes then, so I used them to make a wall around the closet. I then removed things from the closet until the mouse came scurrying out. But it could not leave the wall I had made, I was inside the wall with the mouse, and it had no cover. As it ran around trying to find an exit, I calmly killed it with a few smacks from a rubber mallet.
This is a typical country-boy way of solving animal problems. But I do not think it would be wise to tell that story to people here, or about the time when I killed a mouse with a tonfa when I was in my grad student apartment. They might think of me as some kind of monster, despite the fact that those deaths were swift and humane, much more so than the glue traps scattered around our office right now.

Monday, November 12, 2012

What I Believe

1) Knowledge means falsifiability. The purpose of scientific knowledge is to make testable predictions about observable phenomena. Any belief that does not do this is not scientific and has no place in a fact based discussion.
For example, the belief that Buddhism is the most beautiful religion is in exactly the same category as the belief that Sean Connery is the best James Bond.

2) Humans are fundamentally flawed. Not only are we evil, we are also stupid. The human brain is subject to a wide variety of cognitive flaws. Because of this, almost all of the output the human brain produces has no value in determining the truth about reality. The scientific method is the only known, reliable way of finding knowledge.

3) Because of human flaws, life in a state of nature is nasty, brutish, and short. Even if we lived in a paradise and all of the natural problems of disease and parasites and predators and malnutrition were somehow waved away, we would turn it into Hell by inflicting violence on each other. Observe the historical behavior of all human beings before civilization.

4) The reason we do not currently live in a state of nature is our institutions: rule of law, individual freedom, democracy, the scientific method, private property, free markets. It is theoretically possible that better institutions exist, but we have never observed any desirable and well functioning society that lacks these institutions.

Note: When I use words like better and worse, good and bad, or make any other normative statements, I am referring to the revealed preferences of large numbers of human beings. A better society is one that people choose to move to.

5) Good institutions do not occur easily. They were developed by trial and error over millenia.  Revolutionary change has the potential to threaten these institutions. Theories and philosophies have been shown to be incredibly bad at designing institutions. However, some of our most important institutions were developed as a result of revolutionary experimentation. We can and should improve our institutions with gradual change and local experimentation.

6) Instinctive human morality is a set of behavior patterns that evolved to coordinate the activities of tribes of foragers in a Paleolithic environment. It is not sufficient to create institutions that function well in a modern world, and in some cases it works against good institutions. For example, the inherent repugnance toward dissecting human bodies caused medical progress to be slower and resulted in millions of lives being lost and a great deal of unnecessary suffering.

7) Social facts, and especially economic facts, are rarely the result of human intention or desire. They are the result of complicated impersonal forces that are best understood through rigorous study and the scientific method. Attempting to alter social or economic conditions without the knowledge that came through such careful study is likely to be counterproductive and possibly  disastrous.