I reduced the amount of omega-3 in my diet. I stopped taking flax-seed oil capsules (I had been taking 10 1000-mg capsules/day) and started drinking extra light olive oil (2 tablespoons/day) instead of walnut oil. I made the change at midnight: Tuesday high, Wednesday low. The graph below shows measurements of my balance.

From Saturday through Tuesday, and preceding days, my intake of omega-3 was high; on Wednesday and Thursday it was low.

My balance was worse Wednesday morning than expected by extrapolation, which supports the idea I started with: omega-3 affects my balance. The time course of the change (the impairment was clear in hours) resembles the original observation: I could put on my shoes while standing much more easily the morning after the day I increased my omega-3 consumption.

But, as you can see, there was a problem: My balance rapidly improved during the low omega-3 condition. Although the results support my original idea, they don’t support it as strongly as they might. A comment on a previous post was “Aren’t you worried that your expectation of worse balance will skew the results?” No, I’m not I thought when I read it. I had several reasons for not worrying about the effect of expectations, and now another has come along: Surprising results, which imply that expectations have little effect. I did not expect significant improvement from practice. I had believed that because I balance everyday for hours while standing and walking, there would not be a large practice effect. I was wrong.

Psychologists don’t know much about motor learning. There are few well-established empirical generalizations about what makes motor learning faster or slower. Another gap in our knowledge is about the nature of the underlying change. When you get better with practice, how does your brain change?

After I shifted to low omega-3, I was surprised not only by how much I improved but also by how quickly. Was my improvement due simply to more tests? I plotted my scores versus test number:

This graph suggests that I improved more per test (greater slope) during the low-omega-3 condition than during the high-omega-3 condition. I think it is a spacing effect: During the low-omega-3 condition, I tested more often. During the high-omega-3 condition, I did 14 tests in 3.5 days — 4.0/day. During the low-omega-3 condition, I did 11 tests in 1.2 days — 9.1/day. I tested more often because I wanted to track the decrease. I think this difference in test rate is the reason for the slope difference. This effect is the opposite of the usual spacing effect in learning experiments, in which close-together (”massed”) practice is less effective than widely-spaced practice.

Relevant to the theme of inspiration via self-experiment, these results and my experience gave me several new (at least to me) ideas about motor learning. One was the existence of this spacing effect. Another was that practice changes the brain by increasing how much of the brain is devoted to the task. (The areas used for other tasks shrink.) Practice increases accuracy because more neurons become involved. The output, the action, is an average from a larger sample. One reason I thought of this is that after lots of practice, and I became quite accurate, the circular area on which I was balancing seemed larger. The notion that the brain area used by the task gets larger helps explain the spacing effect. Spacing is important because the brain doesn’t care how often you have done something in the distant past; what matters is how often you are doing it now. Thus the spacing effect helps make efficient use of scarce resources (neurons). The spacing effect occurs because neural activity causes an increase in something (call it X) that slowly fades away. If later activity happens while X is above a threshold, neural rewiring occurs.

The big practice effects and the idea that practice is more powerful when more frequent should interest anyone who wants to improve their balance (and probably other motor skills), from athletes to the elderly. In a simple cheap easy safe way I got better quickly–too quickly, actually. What happened reminds me of Little League: My batting got much better when I started swinging a bat in my backyard.

The lesson for my experimental design is that I should reduce and keep more constant how often I test.

As I mentioned earlier, while measuring my balance I’ve been listening to a book called Cod: The Fish that Changed the World. Around Hour 4 of the book I realized it was related to what I was doing: fish, brain food. Duh!

Each test of balance consists of 5 warmup trials followed by 15 regular trials. Each trial generates one number, a duration: how long I stand on one foot before the other foot touches the floor. It’s is a bit like surfing–balance, balance, balance, balance, balance, wipe out. (Surfers, skateboarders, skiers, snowboarders, gymnasts . . . this may interest you.) I enter the stopwatch times directly into my laptop. Each test lasts about 12 minutes. Because of the book, they’re pleasant.

I made several more baseline measurements of my balance with two changes:

1. To reduce fluctuations in the concentration of omega-3 in my brain, I did my best to take the flaxseed oil capsules as evenly spaced as possible. The general rule was to take 1 every 2.4 hours (= 10 per day). I didn’t take the capsules with me when I left home but I did follow that rule when I was home (not waking up to take them, however).

2. To make the distribution of (log) balance times more Gaussian (normal), I raised the maximum possible time from 30 seconds to 60 seconds. Previously I had stopped the test at 30 seconds; now the cutoff was 60 seconds. The problem was 30 seconds was too common — my balance was too good. Before the change, 3% of baseline measurements (6 out of 210) were 30 seconds. After the change, 12% of measurements (25 out of 210) were between 30 and 60 seconds and <1% (1 out of 210) were 60 seconds.

The graph below shows results (mean & standard error) for 28 sessions.

The early problem (first 10 tests), discussed in my previous post, was that the means were fluctuating too much. A one-way ANOVA, with each test a different level, gave F (9, 140) = 2.6, p = 0.008. This is why I started trying to evenly distribute the flax capsules over the day. This seemed to work. For the last 18 tests, F (17, 252) = 1.0, p = 0.4. Unfortunately there is obviously an upward trend but that is okay because the change I am going to make — much less omega-3 — should if anything impair balance.

Thanks a lot to those who commented on my previous post, very helpful comments. Barleyblair said that after greatly increasing her omega-3 intake she too found her balance greatly improved — not only could she put her socks on while standing she could put her shoes on while standing, which she hadn’t even dreamed of being able to do. Bekel said her sleep is deep and restful because of flaxseed oil. Pauls referred me to a Real-Age test of balance where you stand on one foot with your eyes closed. I tried it. It was way too easy: After two minute I opened my eyes and stopped the test. The table that tells you what the results means only goes up to 28 seconds. If the table is not completely bogus, then my balance is much better than average. Which is consistent with my working hypotheses that (a) the average American gets far too little omega-3 and (b) my brain function — indexed by my ability to balance — greatly improved when I increased my omega-3 intake. Keep in mind that according to conventional recommendations I ate plenty of fish (several servings per week) before increasing my omega-3 intake.

Before doing a simple test of the effects of omega-3 on my balance, I would like to establish a steady baseline and get an idea of what normal variation is. If possible, I would like to reduce normal variation — reduce background noise, in other words. With this goal I have measured my balance 13 times under roughly the same conditions: barefoot, listening to a book (a fascinating book, by the way: Cod: A Biography of the Fish that Changed the World by Mark Kurlansky) while doing the test, 20 trials per test. Each trial consists of standing on one foot on the cutting board on the 0.5-inch platform (see equipment here) and measuring how long until my other foot touches the ground. Each test takes about 10 minutes. I like the book so I enjoy the tests.
Below are the results from all 13 tests as a function of trial number. They show that there is a warmup period lasting 5 trials.

That just refines warmup measurements I posted previously. This is completely new:

The x axis shows when the test was done; points that are close together on the x axis were done close together in time — e.g., an hour apart. I hoped for a steady baseline so that I could go on to more interesting stuff. That is not what I found. I did a one-factor F test to see if there was significant heterogeniety. I used only the last 15 trials of each test, dropping the first 5 “warmup” trials. There were 13 levels (the 13 tests) of one factor. There was a highly reliable (p = .003) effect of test, meaning the variation from one test to the next was too large to be sampling error. And this test did not take into account the obvious clustering — tests close in time had similar results. The clustering makes it even more likely there were real differences in balancing ability from one test (or rather cluster of tests) to the next.

Apparently my balancing ability can change substantially in several hours! (For example, the time between the last test and the next-to-last test, the last in a cluster of three, was 7 hours.) And my test is sensitive enough to detect this! Forgive the exclamation marks. Nothing in my knowledge of psychology makes it obvious or even likely that this would be true — that a measure of quality of brain function would vary so much in hours that it could be detected by single measurements. Or that single measurements would be precise enough to detect such a change. Of course brain function (e.g., alertness) may get worse as you get sleepy but in this case my balance was much better in the evening than in the morning. The differences in my scores had no correlate that I could notice — I didn’t feel noticeably different when I did worse than when I did better.

What might be causing the differences? Body temperature or other circadian rhythm: Unlikely, because one would expect best performance when body temperature is highest, around 4 pm, which does not fit the results very well. More plausible: blood concentration of omega-3. It will be relatively low in the morning because while I was asleep I took no flaxseed oil or walnut oil. It will rise during the day as I consume these. This is consistent with the high measurements in the early evening.

Whatever the cause, these data suggest that something in ordinary life (which includes omega-3 consumption) can improve brain function within hours. If you, dear reader, know of other data that suggests this conclusion please let me know. Drugs and alcohol can quickly change brain function but they are not involved here. Nor am I listening to music, also believed to improve brain function (slightly). I am going to try to reduce fluctuations in omega-3 blood levels and see if I get more uniform measurements. I had a cup of tea with caffeine this afternoon; caffeine consumption is something else I will better control (by eliminating it).