Seth’s blog

I recently met an undergraduate named Samantha who is majoring in Economics at UC Berkeley. She is almost done. I asked her a few questions about her education:

SR: Did UC Berkeley help you figure out what you were good at?

Samantha: No. In UC Berkeley classes you don’t get to do any individual searching. You just have to do what they tell you. Because it’s all theoretical, none of it is very practical. You don’t do any practical projects. The classes don’t give you any idea of what you want to do career-wise.

SR: Did UC Berkeley help you figure out what you enjoy doing?

Samantha: No.

SR: Why not?

Samantha: I’m here just for the name. It scares you away from trying new things. Intimidating class sizes, professors that don’t seem invested in the students.

A student advisor’s view.

Two days ago I explained why the test I was using to measure my mental function many times/day had room for improvement. I wanted a new test much like the old test but with which my accuracy was higher.

I was more accurate with the simple arithmetic test (e.g., 3 + 6) than with the memory test I described two days ago. The crucial difference might have been the number of possible answers. The arithmetic test had 40-odd possible answers; the memory test had 2 (yes and no). Saul Sternberg did a reaction-time experiment in which the number of possible answers was varied from 2 to 8. I don’t know what the accuracy data were but the variance of the reaction times was lower with 8 possible answers even though reaction times were longer. A plausible explanation is that there was much more anticipation with 2 possible answers than with 8. Anticipation can cause errors.

The new test I am trying consists of typing how many letters from the set {A, B, C, D} are among a set of four letters chosen from a much larger set (most of the alphabet). The possible answers are “1″, “2″, “3″, and “4,” each equally likely. For example, I might see T B X A. The correct answer is “2″. I am using R (the programming language) to run this test so I type “2″ with one hand and hit Enter with the other as fast as possible.

Here are the results so far from the new test — the training phase.

These values are taken from fit of a linear model; they are similar to means. As I gain experience with the test I am getting faster. The new test is slower than the old test (which is good — more mental processing).

Consistent with what Sternberg found, variation in reaction times is less with the new test than with the old test even though average reaction times are greater:

This graph shows the standard deviation of residuals from the fitted model. The units are reciprocal seconds (x 10) because I did a reciprocal transformation before fitting the model. The reciprocal transformation made the reaction times close to normally distributed.

Here is accuracy:

The new test feels easier than the old test, but so far there is little difference.

Overall it seems to be a step in the right direction. Reduction in variation of reaction times means more sensitive measurements.

The experiments I am planning are very simple: Test myself regularly (say, every half-hour), eat something. If the measurements are steady, it is very easy to see an effect. As far as I know, such experiments have never been done. One reason, I think, is that they require self-experimentation: It is no trouble for me to do the test (which takes 4 minutes) 100 times in a week and thereby reach a steady state. But to have someone else do the test 100 times as preparation — especially if the test were done in a lab — would be very difficult.

As regular readers of this blog know, I propose that art exists because in our evolutionary past payment to artists promoted material science — learning how to create new materials with useful properties. For example, red stained glass.

Medieval artisans unknowingly became nanotechnologists when they made red stained glass by mixing gold chloride into molten glass. That created tiny gold spheres, which absorbed and reflected sunlight in a way that produces a rich ruby color.

The gold spheres have to be about 25 nanometers in diameter to get this effect.

Thanks to Joshua Schrier.

During a trip to Los Angeles a few weeks ago, I noticed that my scores on several mental tests were better all of a sudden. The apparent cause was that I had taken flaxseed oil at an unusual time. Normally I took it about 10 hours before the tests; in this case I had taken it about 4 hours before.

Does flaxseed oil have a short-lived effect on brain function? When I got home I tried to find out. Rather than doing a set of four tests once per day I switched to one test many times per day (e.g., 10 times). This would allow detection of short-lived ups and downs in my mental function.

The test I used required nothing but my laptop. I usually have my laptop with me so such a test is much easier to do throughout the day than a task that requires other equipment. The test consisted of four blocks of 50 trials each. For each block I memorized a new set of three digits (e.g., 0 1 7). On each trial I saw 1, 3, or 5 digits and pressed a keyboard key as quickly as possible to indicate if any of the memorized digits is in the displayed set. For example, if the memory set was 0 1 7 and the display set was 3 2 8 the correct answer was “no” (which I indicated by pressing “4″).

The trials were packed together as closely as possible: As soon as I answered, the next set appeared. It took about 3 minutes to do 200 trials.

I did frequent measurements for four or five days. They appeared to confirm what the Los Angeles measurements suggested: Flaxseed oil did have a short-term effect. But two things muddied the water:

1. Baseline measurements were not always as steady as I would like. There were ups and downs that seemed too large to be random variation. The curious and exciting thing was that these ups and downs usually had a possible explanation — something had changed. For example, the measurements would be X1, X2, X3, Y. X1, X2, and X3 are close; Y is quite different. Between X3 and Y I had eaten a meal.

2. The task was difficult. I was about 88% correct and it was hard to do better. With any reaction-time task there is a speed-accuracy tradeoff: If you are slower, you can be more accurate. In this particular case this is a problem because it is an added source of variation and may reduce reaction-time differences: Rather than becoming slower, I become less accurate (or rather than becoming faster I become more accurate).

Problem #1 is easy (if slightly unpleasant) to solve: Keep the situation more constant. Eat less during the measurement period, etc.

To reduce Problem #2 I am learning a new task. I will go into detail tomorrow.

Robin Hanson has doubts about the long-term value of blogging — especially his own:

My main doubt is whether this will accumulate . . . We get over a thousand readers a day here, and those readers must be influenced somehow. But do those influences add up to a long term net effect?

Consider that before the farming revolution humanity’s knowledge accumulated very slowly. Each person learned a great deal over the course of his lifetime, both by discovering new insights for himself and by listening to others. Nevertheless, the distribution of knowledge in the population hardly changed; each new generation had to rediscover and relearn the same insights all over again.

Before farming, I believe new insights were passed down in three ways. 1. Stories. Stories are to teaching as good food is to nourishment. Whenever I tell a story, my students pay close attention. 2. Apprenticeships. 3. Specialists talking to each other — a manifestation of the Fan Club Instinct. Blogging is a new version of Method 3. When old specialists talked to young specialists, knowledge was passed down. Robin is young, but his posts are influencing even younger persons.

I think blogging is a good use of my time for several reasons. 1. Advertising. I hope blogging will draw attention to my papers and book and future work. Brian Wansink nicely made this point (scientists should advertise). 2. Quasi-reinforcement. Blogging divides a big task (writing a book or paper) into much smaller tasks (writing posts). 3. Data collection. Because of my omega-3 posts, two other people gathered data useful (very) to me. Tim Lundeen’s data led me to study new tasks. Tyler Cowen’s experience with flaxseed oil is enormously important to my omega-3 research.

But I have to agree with Robin that blogging sometimes seems too seductive — that I should write fewer posts like this one and more that fit into the book and papers I want to write. I keep thinking of something Philip Weiss said in his blog: For men, the most enjoyable form of expression is the Op-Ed piece.