Sunday, June 14, 2015

Associated vs Relevant

Also cross-posted to LessWrong.

The List of Nuances (which is actually more of a list of fine distinctions - a fine distinction which only occurred to its authors after the writing of it) has one glaring omission, which is the distinction between associated and relevant. A List of Nuances is largely a set of reminders that we aren't omniscient, but it also serves the purpose of listing actual subtleties and calling for readers to note the subtleties rather than allowing themselves to fall into associationism, applying broad cognitive clusters where fine distinctions are available. The distinction between associated and relevant is critical to this activity.

An association can be anything related to a subject. To be relevant is a higher standard: it means that there is an articulated argument connecting to a question on the table, such that the new statement may well push the question one way or the other (perhaps after checking other relevant facts). This is close to the concept of value of information.

Whether something is relevant or merely associated can become confused when epistemic defensiveness comes into play. From A List of Nuances:
10. What You Mean vs. What You Think You Mean
  1. Very often, people will say something and then that thing will be refuted. The common response to this is to claim you meant something slightly different, which is more easily defended.
    1. We often do this without noticing, making it dangerous for thinking. It is an automatic response generated by our brains, not a conscious decision to defend ourselves from being discredited. You do this far more often than you notice. The brain fills in a false memory of what you meant without asking for permission.

As mentioned in Epistemic Trust, a common reason for this is when someone says something associated to the topic at hand, which turns out not to be relevant.

There is no shame in saying associated things. In a free-ranging discussion, the conversation often moves forward from topic to topic by free-association. All of the harm here comes from claiming that something is relevant when it is merely associated. Because this is often a result of knee-jerk self-defense, it is critical to repeat: there is no shame in saying something merely associated with the topic at hand!

It is quite important, however, to spot the difference. Association-based thinking is one of the signs of a death spiral, as a large associated memeplex reinforces itself to the point where it seems like a single, simple idea. A way to detect this trap is to try to write down the idea in list form and evaluate the different parts. If you can't explicitly articulate the unseen connection you feel between all the ideas in the memeplex, it may not exist.

Utilizing the power of associations is a powerful tool for creating a good story (although, see item #3 here for a counterpoint). Repeating themes can create a powerful feeling of relevance, which may be good for convincing people of a memeplex. Furthermore, association is a wonderful exploratory tool. However, it can turn into an enemy of articulated argument; for this reason, it is important to tread carefully (especially in one's own mind).

Wednesday, June 10, 2015

Epistemic Trust: Clarification

Cross-posted to LessWrong Discussion.

A while ago, I wrote about epistemic trust. The thrust of my argument was that rational argument is often more a function of the group dynamic, as opposed to how rational the individuals in the group are. I assigned meaning to several terms, in order to explain this:

Intellectual honesty: being up-front not just about what you believe, but also why you believe it, what your motivations are in saying it, and the degree to which you have evidence for it.

Intellectual-Honesty Culture: The norm of intellectual honesty. Calling out mistakes and immediately admitting them; feeling comfortable with giving and receiving criticism.

Face Culture: Norms associated with status which work contrary to intellectual honesty. Agreement as social currency; disagreement as attack. A need to save face when one's statements turn out to be incorrect or irrelevant; the need to make everyone feel included by praising contributions and excusing mistakes.

Intellectual trust: the expectation that others in the discussion have common intellectual goals; that criticism is an attempt to help, rather than an attack. The kind of trust required to take other people's comments at face value rather than being overly concerned with ulterior motives, especially ideological motives. I hypothesized that this is caused largely by ideological common ground, and that this is the main way of achieving intellectual-honesty culture.

There are several important points which I did not successfully make last time.
  • Sometimes it's necessary to play at face culture. The skills which go along with face-culture are important. It is generally a good idea to try to make everyone feel included and to praise contributions even if they turn out to be incorrect. It's important to make sure that you do not offend people with criticism. Many people feel that they are under attack when engaged in critical discussion. Wanting to change this is not an excuse for ignoring it.
  • Face culture is not the error. Being unable to play the right culture at the right time is the error. In my personal experience, I've seen that some people are unable to give up face-culture habits in more academic settings where intellectual honesty is the norm. This causes great strife and heated arguments! There is no gain in playing for face when you're in the midst of an honesty culture, unless you can do it very well and subtly. You gain a lot more face by admitting your mistakes. On the other hand, there's no honor in playing for honesty when face-culture is dominant. This also tends to cause more trouble than it's worth.
  • It's a cultural thing, but it's not just a cultural thing. Some people have personalities much better suited to one culture or the other, while other people are able to switch freely between them. I expect that groups move further toward intellectual honesty as a result of establishing intellectual trust, but that is not the only factor. Try to estimate the preferences of the individuals you're dealing with (while keeping in mind that people may surprise you later on).

Wednesday, June 3, 2015

Simultaneous Overconfidence and Underconfidence

Follow-up to this and this. Prep for this meetup. Cross-posted to LessWrong.
Eliezer talked about cognitive bias, statistical bias, and inductive bias in a series of posts only the first of which made it directly into the LessWrong sequences as currently organized (unless I've missed them!). Inductive bias helps us leap to the right conclusion from the evidence, if it captures good prior assumptions. Statistical bias can be good or bad, depending in part on the bias-variance trade-off. Cognitive bias refers only to obstacles which prevent us from thinking well.

Unfortunately, as we shall see, psychologists can be quite inconsistent about how cognitive bias is defined. This created a paradox in the history of cognitive bias research. One well-researched and highly experimentally validated effect was conservatism, the tendency to give estimates too middling, or probabilities too near 50%. This relates especially to integration of information: when given evidence relating to a situation, people tend not to take it fully into account, as if they are stuck with their prior. Another highly-validated effect was overconfidence, relating especially to calibration: when people give high subjective probabilities like 99%, they are typically wrong with much higher frequency.

In real-life situations, these two contradict: there is no clean distinction between information integration tasks and calibration tasks. A person's subjective probability is always, in some sense, the integration of the information they've been exposed to. In practice, then, when should we expect other people to be under- or over- confident?

Simultaneous Overconfidence and Underconfidence

The conflict was resolved in an excellent paper by Ido Ereve et al which showed that it's the result of how psychologists did their statistics. Essentially, one group of psychologists defined bias one way, and the other defined it another way. The results are not really contradictory; they are measuring different things. In fact, you can find underconfidence or overconfidence in the same data sets by applying the different statistical techniques; it has little or nothing to do with the differences between information integration tasks and probability calibration tasks. Here's my rough drawing of the phenomenon (apologies for my hand-drawn illustrations):

Overconfidence here refers to probabilities which are more extreme than they should be, here illustrated as being further from 50%. (This baseline makes sense when choosing from two options, but won't always be the right baseline to think about.) Underconfident subjective probabilities are associated with more extreme objective probabilities, which is why the slope tilts up in the figure. Overconfident similarly tilts down, indicating that the subjective probabilities are associated with less-extreme objective probabilities. Unfortunately, if you don't know how the lines are computed, this means less than you might think. Ido Ereve et al show that these two regression lines can be derived from just one data-set. I found the paper easy and fun to read, but I'll explain the phenomenon in a different way here by relating it to the concept of statistical bias and tails coming apart.

The Tails Come Apart

Everyone who has read Why the Tails Come Apart will likely recognize this image:
The idea is that even if X and Y are highly correlated, the most extreme X values and the most extreme Y values will differ. I've labelled the difference the "curse" after the optimizer's curse: if you optimize a criteria which is merely correlated with the thing you actually want, you can expect to be disappointed.

Applying the idea to calibration, we can say that the most extreme subjective beliefs are almost certainly not the most extreme on the objective scale. That is: a person's most confident beliefs are almost certainly overconfident. A belief is not likely to have worked its way up to the highest peak of confidence by merit alone. It's far more likely that some merit but also some error in reasoning combined to yield high confidence.

In what follows, I'll describe a "soft version" which shows the tails coming apart gradually, rather than only talking about the most extreme points.
Statistical Bias

Statistical bias is defined through the notion of an estimator. We have some quantity we want to know, X, and we use an estimator to guess what it might be. The estimator will be some calculation which gives us our estimate, which I will write as X^. An estimator is derived from noisy information, such as a sample drawn at random from a larger population. The difference between the estimator and the true value, X^-X, would ideally be zero; however, this is unrealistic. We expect estimators to have error, but systematic error is referred to as bias.

Given a particular value for X, the bias is defined as the expected value of X^-X, written EX(X^-X). An unbiased estimator is an estimator such that EX(X^-X)=0 for any value of X we choose.

Due to the bias-variance trade-off, unbiased estimators are not the best way to minimize error in general. However, statisticians still love unbiased estimators. It's a nice property to have, and in situations where it works, it has a more objective feel than estimators which use bias to further reduce error.

Notice, the definition of bias is taking fixed X; that is, it's fixing the quantity which we don't know. Given a fixed X, the unbiased estimator's average value will equal X. This is a picture of bias which can only be evaluated "from the outside"; that is, from a perspective in which we can fix the unknown X.

A more inside-view of statistical estimation is to consider a fixed body of evidence, and make the estimator equal the average unknown. This is exactly inverse to unbiased estimation:

In the image, we want to estimate unknown Y from observed X. The two variables are correlated, just like in the earlier "tails come apart" scenario. The average-Y estimator tilts down because good estimates tend to be conservative: because I only have partial information about Y, I want to take into account what I see from X but also pull toward the average value of Y to be safe. On the other hand, unbiased estimators tend to be overconfident: the effect of X is exaggerated. For a fixed Y, the average Y^ is supposed to equal Y. However, for fixed Y, the X we will get will lean toward the mean X (just as for a fixed X, we observed that the average Y leans toward the mean Y). Therefore, in order for Y^ to be high enough, it needs to pull up sharply: middling values of X need to give more extreme Y^ estimates.

If we superimpose this on top of the tails-come-apart image, we see that this is something like a generalization:

Wrapping It All Up

The punchline is that these two different regression lines were exactly what yields simultaneous underconfidence and overconfidence. The studies in conservatism were taking the objective probability as the independent variable, and graphing people's subjective probabilities as a function of that. The natural next step is to take the average subjective probability per fixed objective probability. This will tend to show underconfidence due to the statistics of the situation.

The studies on calibration, on the other hand, took the subjective probabilities as the independent variable, graphing average correct as a function of that. This will tend to show overconfidence, even with the same data as shows underconfidence in the other analysis.

From an individual's standpoint, the overconfidence is the real phenomenon. Errors in judgement tend to make us overconfident rather than underconfident because errors make the tails come apart so that if you select our most confident beliefs it's a good bet that they have only mediocre support from evidence, even if generally speaking our level of belief is highly correlated with how well-supported a claim is. Due to the way the tails come apart gradually, we can expect that the higher our confidence, the larger the gap between that confidence and the level of factual support for that belief.

This is not a fixed fact of human cognition pre-ordained by statistics, however. It's merely what happens due to random error. Not all studies show systematic overconfidence, and in a given study, not all subjects will display overconfidence. Random errors in judgement will tend to create overconfidence as a result of the statistical phenomena described above, but systematic correction is still an option.