Thursday, July 13, 2006

The mind is like an iceberg, but much smaller. And warmer.

It still strikes me, from time to time, how amazing it is that we can "use" our minds without understanding them.

It's like driving. We can use a car without knowing how it works. We just know which buttons to push when and we get what ge want. More accurately, using our minds is like using some amazing alien spacecraft, the hood of which we can't open.

its also easy to underestimate hö much of that our mind does is unconscious. We can't describe faces very well, or even picture them very clearly, yet we are remarkably good at recognizing them. We understand the sound "bored" in any context, but have difficulty recalling every sense of the sound at once: (being bored with a book, a wooden board, a hole bored in a board, a board of directors, the first sound in "bordello", room and board, to board a train, etc.).

It's a little like being a CEO of a company, being the conscious part of your mind. You've got a huge hierarchy of workers below you whose job you could never do. But when things are needed, for the most part, they show up. You're watching a movie and someone pokes their head in and says "There's a Tarantino influence here."

And we have no idea how we come up with the sentences we create. Like Magic they show up from god-knows-where, extraordinarily fast. Think of the common but uncommonly strange situation of two psycholinguists using language effortlessly to argue about language generation.

It's sometimes daunting, terrifyingly difficult to figure out. It's also the most important thing in the world.

The Hippocampal Memory Paradox

There's something I find paradoxical about hippocampal memory theory. This theory states that new memories are stored somewhere temporarily, and then permanently stored in long-term memory (LTM)later.

On the one hand, there's good evidence for it. Hippocampal damage inhibits new LTM storage, even though previously encoded items in LTM are intact. The famous patient HM had his hippocampus (among other things) removed and was unable to store new episodic memories (memories of what happens). HM can still store procedural and perhaps semantic memories as well. So this makes sense. Not all memories need to be in LTM, so they are temporarily put somewhere and the important ones stored in LTM later.

On the other hand, it makes no sense to me, because the symbols in the mind only make sense given the other symbols they are connected to. So if you see me wearing a black pencil behind my ear, how are you going to store a temporary representation of that without using the symbols for black, pencil, and JimDavies that are a part of the semantic network used by LTM?

One way out of this mess is to suggest that it works like writing: There is a code that the temporary memories are stored as. For example, if you read the words "JimDavies wore a black pencil" you use those words as cues into your semantic network to know what it means. So perhaps the temporary store is not a meaningful memory at all-- it's only meaningful after being interpreted by the existing LTM. That is to say, before it's stored in LTM it's a bunch of pointers to symbols in LTM.

I call this the "language of memory theory."

Tuesday, July 11, 2006

Comments on "An Inconvenient Truth"

I saw "An Inconveinent Truth" the other night. It's mostly Al Gore's presentation on global warming, and it's persuasive. It should be, since he claims to have given the talk over a thousand times. A good deal of the film shows Gore sitting at his iBook working on the presentation.

As a scientist I feel it's my responsibility to take a critical eye to scientific presentations. I believe global warming is happening and is caused at least in part by human activities. Please read this essay with that in mind-- I want to improve the nature of the debate and keep it rooted in good science. My critiques of the film are meant to be constructive.

Listening to Scientists

It seems that the authority on the other side of this debate is novelist Michael Crichton. People often critisize Chrichton because he's not a scientist. If someone is a scientist they gain credibility. If you are a climatologist, however, you don't care about that-- you can read it and judge it for yourself because you have all the background you need. For an atmospheric scientist to dismiss Chrichton because he's not a scientist is an ad hominem attack. Einstein was a patent clerk when he made some of his best theories, with no physics training at all.

(What's an ad hominem attack?)

For laypersons, however, credibility is crucial. You can't read something and know what they're not telling you, or know that the technical aspects of what they are saying make no sense. So in this sense laypersons should take Crichton's words with a grain of salt, and indeed defer to a scientist.

Let us not forget that Al Gore is not a scientist either. He's smart and well-informed, but so is Chrichton, who, before "State of Fear" came out, was praised for his books being so educational.

Complaints about the presentation

Now I'm not a climatologist, but I am a scientist and I have some complaints about the presentation. It's a difficult design challenge, to be sure, to address laypersons while remaining scientific. Most people don't want to see citations. It bores them, and they don't know what pubs are legit, and they won't follow up with reading. But scientists do. Gore cites nobody in this talk. I went to his website for the film,, and with delight saw a link for "the science!" Unfortunately, it's a fact sheet, with no scientific citations whatever. (Note Crichton's essay has numerous citations). I'm not saying the science isn't there, but I want to see it! I had a similar problem with Jared Diamond's book "Collapse," except that I think for that book the science does not exist at all, anywhere. Sad. Diamond was my hero for years. "Guns, Germs, and Steel" is the second-best book I ever read. But I digress.

This is especially problematic when reading critiques of the film, such as this one written by an MIT atmospheric scientist: Don't Believe the Hype.
by Richard S. Lindzen, Sunday, July 2, 2006 12:01 a.m. EDT
. He says things like The Greenland ice sheet is growing. But he doesn't cite anybody either (What's the matter, WSJ? No room for citations? Might take up valuable editorial space, God forbid!) With Gore not citing anyone, and Lindzen not citing anyone, what is a responsible intellectual to do? (Apparently, blog about it.)

Balance of Economy and Environmentalism

At one point Gore brings up a slide presented to him to demonstrate trying to balance the economy with environmental concerns. In the graphic there is a scale with gold bars on one side and the earth on the other. He makes fun of this graphic, mocking the choice between gold and the entire planet. This is sophistry. The gold bars just symbolize the economy, and the image of the earth is a well-known symbol for environmental concerns. You know this, Gore knows this, most of the audience could figure it out, so why does he do this? He gets a cheap laugh out of it. Makes me angry.

He uses it as part of his argument that we need not have a trade-off between the two concerns. This is something I really want to hear about. Is it a false choice? He uses the above rhetorical trick, then he goes on to show that fuel efficient cars are selling best. Here he confuses causality with correlation. Maybe the cars are not selling best because they are fuel efficient, but are both selling best and are fuel efficient because they are better made cars in general. He gives us no information to resolve this ambiguity. And even if he were right, it's hardly enough to generalize to all economic vs. environmental concerns. Clearly pollution does involve such a trade off-- it costs money to not pollute. Taking care of waste safely is much more expensive than dumping it in a river. People don't spend money to pollute. Why are the concerns related to global warming different? (They might be, but Gore is unconvincing on this issue.)

As far as I can remember, that's all he presents in response to the idea that there's a trade off!

Please leave comments. I really wanted this film to be excellent, not just persuasive.

Reincorporation and Repetition in Art

My friend Dustin recently asked me why improv audiences are so delighted with reincorporation.

Reincorporation is bringing back ideas and phrases from earlier in a performance (typically, but not always, the same scene).

I don't think it's really known why it works so well, but I am very certain from my personal experience that it does. In this entry I will speculate on why, from a cognitive science perspective.

When you experience something again, you encode it into memory, in some new context. The first thing that happens is you are aware that some stimulus has repeated-- every time you see something it increases the probability that you will see it again. As a result at some level you think it's important. We are wired to pay attention to patterns so that we can better behave in our environment.

The other thing is that whatever we're re-experiencing we're learning more about. We are deepening our understanding of the stimulus by associating it with a new context.

I love the book "The Unbearable Lightness of Being" because its thesis is that things are only meaningful to us because they repeat. Indeed, the book recounts the same events over and over with new perspectives.

This works not only for improv, but for the arts in general. In visual art, repeating visual patterns (sometimes called "rhymes") are effective.

Commedians will often end their act with a joke told before. For example, Jerry Seinfeld had an act in which he complained about people saying "say hi to him for me." Then we talked about Jared, the Subway diet guy. At the end of the act, he said "And if you see Jared, say hit to him for me." The audience roared with appreciation. They were in effect saying "thank you for enriching my memory system."

In music and poetry we have rhyming and alliteration, which is a re-incorporation of phonemes.

Also in music we have repeating beats, melodies, and lyrics. A good example for lyrics comes from the song "Nothing" from "A Chorus Line." In this song Morales tells of being in an acting class in which she was supposed to feel like an ice cream cone, or a bobsled. Unfortunately, as the chorus repeats, she "felt nothing." The acting teacher tells her she's worthless. At the end of the song she recalls seeing that the teacher had died. She cried because she "felt nothing." Notice how feeling nothing takes on a new meaning at the end. I notice a lot of good songs have choruses that mean something different at the end of the song.

Sunday, July 09, 2006

Big changes in my life are accompanied by a sound from "Time Pilot"

Time Pilot is an 80s arcade game I liked to play. In this game you're a plane and you have to shoot other planes. When you've cleared a level, you go on to a new one, in a different time period. You're a time travelling pilot. Anyway, when this happens, there's this booming sound like a distant explosion. I always liked that sound.

When I have a big change in my life, and certainly whenever I move, I make this sound. It's symbolic for me. I make it in the car when I'm driving out of town for the last time. I also made it when I got accepted for grad school, and when I got the job here at Carleton.

I just realized it's an interesting analogy-- time travelling in a videogame and life changes.

Tuesday, July 04, 2006

Hypothesis-confirming biases

I hired movers, and they sent over a guy to give me an estimate. He looked over my apartment, which is stuffed to the gills. When the actual movers came, there were 20 more boxes than were estimated, costing $800 more than the estimate (I hired them to pack as well as move the stuff.) I called and complained, and the guy who gave the estimate implicitly accused me of putting much more stuff in the apartment: "I'm never 20 boxes off," he said.

Well he was. My apartment was full of papers and books, as well as a pile of boxes full of... wait for it... papers and books. Someday I need to learn to dispose of a piece of paper. The movers said they kept finding stuff behind stuff, and then finding stuff behind that. The whole thing weighed about 5k pounds. The movers ran out of tape. They'd brought ten rolls, and the last three boxes were not taped on the top. I know one person who will not be the least bit impressed with these numbers-- Anthony, how many pounds of stuff did you end up having to get moved?

This estimate guy is behaving in hypothesis-confirming behavior, I think. He gave this estimate, and when the estimate is off, he would rather believe I added stuff to the apartment than believe that he was far off. Given the information he has, both are possible, but you see what this does-- since he will interpret this episode as one in which he was not off, the next time it happens he will also be likely to disblieve it because, as he said this time "I'm never 20 boxes off." It should be very hard to convince this fellow that his estimates are ever off.

It's a general behavioral tendency in human beings: to look for evidence that supports your hypothesis rather than to search for evidence that disconfirms it. It allows normally smart people to believe weird things, such as the moon effect. The moon effect theory holds that people behave differently (usually more actively or criminally) when there is a full moon. Scientists have done studies of this and found this to be bunk.

This paragraph debunks the common theories behind the moon effect. Skip it if you want. When I hear people argue for the moon effect, they say things like "The moon effects the tides, and we are 98% water, so it follows that the moon should effect us too." There are several things wrong with this viewpoint. First, whether the moon is full or not has nothing to do with how close it is to the earth. Remember that the moon can be "up" even in the daytime; we just don't see it. Second, the fact that we are made of water has nothing to do with anything. The moon affects tides through gravitation, and gravity affects all atoms equally according to weight. That is, it pulls on water no more and no less than any other matter. Third, even if there was a gravitation effect, because gravity reduces so sharply with distance, there is a greater gravitational effect of a skyscraper you're standing next to than the moon. To be consistent these peopel should also believe in the skyscraper effect. Finally, there's no evidence nor plausible reason to think that a gravitational pull on a person should effect how they behave.

Nonetheless, people continue to believe. I've heard from a psychologist who studied the moon effect that if you ask police officers and hospital nurses they will swear it's real. How can this be?

Here's how it works: People hear about the moon effect. Once the idea is in their minds, they notice whenever something strange happens AND there is a full moon. They never notice when people act normally during a full moon, or when people act strangely when there's not a full moon. What's to notice? Only the combination of the two triggers the memory of the moon effect at all. So as you go through life, you believe in the moon effect more and more. The negative evidence just does not get remembered.

I will leave the analogy with religious beliefs as an exercise for the reader.

One of the things that makes science so great is that it works against some of our inherent psychological biases. It requires careful observation and recording, which mediates the hypothesis-confirming bias. Scientists often support a theory by failing to find disconfirming evidence. Awesome!

Saturday, July 01, 2006

Online textbooks, Wikibooks, and Wikiversity

Some of you know that I have ambitions to create an online text book for AI and possibly for Cognitive Science. The idea is that students in classes (mostly in my classes) would be assigned topics, and as part of their assignment they must write a chapter or a section for the online text book. Or alternately, they can add to or improve an existing entry. Eventually, perhaps 20 years later, the textbook might be good enough to use in a university course. My philosophy behind this approach is that student's work should not be wasted, but used to supplement other research and learning has been published in this book chapter:

Davies, J. R. (2001). Ocelots are endangered South American wild cats. In Ohler, J. (Ed.) Future Courses: A Compendium of Thought About the Future of Technology and Education. AIT Technos Press.

As I see it the two advantages of the book being online that anyone with an web connection can access it, and the web medium allows for multimedia, including animations and quizzes to help you study.

As it turns out, there are two very exciting projects underway already: Wikibooks and Wikiversity. A "wiki" is a web page that anyone can edit easily through a web browser. That is, each page in the wiki has an "edit" button that you can press and instantly change the text. The most popular wiki is Wikipedia. Since anyone can edit it people tend to be skeptical about its content. I find that these people usually have not used it much. From what I can see, the content is often superb. I now use it as my main source of information about random topics I'm interested in. Nature did a comparative study of Wikipedia and The Encyclopedia Brittanica and found the accuracy to be about the same.

Wikibooks is a website that has a wiki approach to writing whole books. Turns out there is one about Artificial Intelligence already under discussion. As of the writing of this article, they are still deciding on the table of contents. I have two feelings about this. One is that the impact of my student's work would be greater if they contributed to this higher-profile online book. My other thought is that I would not get the same personal credit as I would if I had my own website with me listed as the editor. Finally, my online textbook will probably suck in comparison after ten years, unless I do a lot of things the wikibook does not, such as quizzes, animations, etc.

So it seems the right thing to do is to require the students to contribute to the wikibook, perhaps in addition to my own. Any dissenting opinions?

The other exciting development is the wikiversity. As I see it the potential of this page is to provide complete university curricula online, free. Very exciting.