There are a lot of explanations of Bayes' Theorem, so I won't get into the technicalities. I will get into why it should change how you think. This post is pretty introductory, so free to totally skip it if you don't feel like there's anything about Bayes' Theorem that you don't understand.

For a while I was reading LessWrong and not seeing what the big deal about Bayes' Theorem was. Sure, probability is in the mind and all, but I didn't see why it was so important to insist on bayesian methods. For me they were a tool, rather than a way of thinking. This summary also helped someone in the DC group.

After using the Anki deck, a thought occurred to me:

Bayes theorem means that when seeing how likely a hypothesis is after an event, not only do I need to think about how likely the hypothesis said the event is, I need to consider everything else that could have possibly made that event more likely.

To illustrate:

pretty clearly shows how you need to consider P(e|H), but that's slightly more obvious than the rest of it.

If you write it out the way that you would compute it you get...

where h is an element of the hypothesis space.

This means that every way that e could have happened is important, on top of (or should I say under?) just how much probability the hypothesis assigned to e.

This is because P(e) comes from every hypothesis that contributes to e happening, or more mathilyeX P(e) is the sum over all possible hypotheses of the probability of the event and that hypothesis, computed by the probability of the hypothesis times the probability of the event given the hypothesis.

In LaTeX:

where h is an element of the hypothesis space.

Summary: Neuroimaging scans and EEG readings comparing nonconscious and conscious stimuli are compared, showing particular patterns in conscious processes. These findings are in line with predictions made by the Global Workspace Theory of consciousness, in which consciousness is closely related to interaction between specialized modules of the brain.

When a bunch of photons hit your eye, it unleashes a long chain of cause and effect that leads to an image being mapped in your brain. When does that image become conscious?

Merikle et al performed experiments in the 80s which helped to resolve this question. In the Stroop task, people are asked to read words written in a different color than the word. Words written in their color (green) are easier to read than those not in their color (also red). Merikle modified the stroop task, using only two colors (red and green), and using the word to prime subjects to describe the color. As was expected, when "green" comes before a green square, subjects respond faster than with no priming.

However, when the situation is regularly reversed and the "red" prime normally comes before a green square (and vice versa) people also respond faster to similar levels. That is to say, subjects are able to notice that the prime and stimulus are incongruent, and act on that information to respond faster to the stimuli.

When the reversed prime ("red" before green) is flashed for such a short time span that people don't report seeing it, they are unable to use this information to react faster to the green stimulus, and the typical Stroop effect is observed -- being subliminally primed with a congruent color speeds up recognition, being subliminally primed with an incongruent color slows it.

http://en.wikipedia.org/wiki/P3b

I found this article while researching something else and I was intrigued. Is this a neural correlate of confusion?

The P3b has been a prominent tool used to study cognitive processes for several decades. More specifically, this ERP component has played a key role in cognitive psychology research on information processing. Generally speaking, improbable events will elicit a P3b, and the less probable the event, the larger the P3b.^[3] However, in order to elicit a P3b, the improbable event must be related to the task at hand in some way (for example, the improbable event could be an infrequent target letter in a stream of letters, to which a subject might respond with a button press). The P3b can also be used to measure how demanding a task is on cognitive workload.^[4]

If so, awesome. Hats which actually do sound an alarm when your models are proven wrong could be arranged. I suspect that there might be things that make it not useful for that (like, if it also correlates with a bunch of other things). Seems like it's at least worth mentioning.

Discussion article for the meetup : UMD Meetup

Discussion article for the meetup : UMD Meetup

Thomas Metzinger is a philosopher who pays lots of attention to cognitive science and psychology, and likes to think about consciousness. Most of the interesting ideas that follow come from his books The Ego Tunnel and Being No One. I hope to write a series of posts summarizing some of the evidence and arguments in Being No One, which focuses on consciousness.

Blindsight¹

Blindsight patients have damage to their primary visual cortex (V1), leading to a scotoma, or area of blindsight in the visual field. Most but not all visual signals go through V1, so they can still influence the brain in very restricted channels. Blindsight patients don't report seeing things in their scotoma, and don't initiate plans based on it. If they're thirsty and there's a bottle of water in their scotoma, they don't pick it up and drink it.

Human subjects and animal subjects are treated differently in psychological experiments regarding what they do and don't know. Humans are generally asked to report on their own experience, while animal actions are observed. We get interesting results when we ask people to report on their experience, while also observing their actions.

If you ask a blindsight patient what they see in their scotoma, they respond to the point that they can't see anything there. However, if you tell them to do things like "grab the thing in your scomata" they can grasp it. If you ask them to guess what's in it, they can perform better than chance. Some blindsight patients can tell if something is moving in their scotoma, but they can't tell you what it is. They often describe this awareness as a hunch.

Most people consider it fair to say that blindsight patients are not conscious of the things in their scotoma.

Attention and Conscious Experience

Patients with blindsight can act on visual information in their scotomas in some ways, but they can't notice it.

Metzinger argues that humans don't have a conscious experience of what we can't pay attention to. Note: There's a difference between can't pay attention to, and not currently paying attention to.

Visual information in the scotoma isn't accessible to the parts of my brain that plan, or the parts that cause me to say "I can see X". My unconscious is able to refer to this information for things in forced choice situations, but the information isn't available to me.

Constraints on Theories of Consciousness

Any theory which says that you need to be conscious in order to do things is probably wrong. Also, robots work. And machine learning exists. See also unconscious goals.

It's possible for your brain to refer to something, but not have it be consciously available to you. It's also possible to change what these things are.

The parts of your brain causing you to say that you notice something can be cut off from the parts that let you do things. This implies that some neural processes lead to you being conscious and others don't, and that those processes can be interrupted without ruining everything.

Citations, Notes:

¹"The Case of Blindsight" by Weiskrantz in the Blackwell Companion to Consciousness (you can get it here, though there are other place on the internet that talk about blindsight)

Heavily drawn from The Ego Tunnel and Being No One (both by Metzinger).

Thanks to John Salvatier for reviewing drafts of this post.

Discussion article for the meetup : University of Maryland, Influence

Discussion article for the meetup : University of Maryland, Influence

Discussion article for the meetup : Northern Virginia: Nonviolent Communication

Discussion article for the meetup : Northern Virginia: Nonviolent Communication

Discussion article for the meetup : University of Maryland

Discussion article for the meetup : University of Maryland

Just a piece about rejection therapy I did yesterday on the subway. The language might be a bit hyperbolic, but I was kind of on-edge last night. It seemed like it might be a fun story, I want to get better at writing, and gooey self-disclosure seems to be in vogue, so I posted it. If you don't like reading about feelings, then don't continue.

Hope you enjoy,

Story

I felt electric. It was as if my blood was made up of cool and charged water, chilling my bones as it energized my flesh, making me feel like at any moment my body could snap into doing something else. I got out of my seat, and lurched over to one of the hand holds in front of me. Reflecting, I decided that I would be in a more central position if I stood in front of the exit door, and my body swayed over there.

My head was a bit foggy, but my path was clear. The outside world or my thoughts were racing by, but I could couldn't tell which. The girl who had glanced at me while I was sitting down looked up. I noticed a few other eyes glancing up towards me while I was walking, and felt like I was at risk for shattering into a bunch of pieces. I was ready for anything, but there was only one thing I was thinking of doing.

“Excuse me.

“This probably sounds kind of creepy.

“But would anyone like to have a conversation?”

The train stopped moving.

I intended to look around, but I'm not convinced that I actually did. I wanted to have some time to see other people's reactions, but as far I can tell, I could only look at an oblique angle through the window that was above where I was sitting when I was reading.

I had actually expected someone to say yes. I looked around expectantly to the side of people who did not fit my demographic expectations of a person who would actually say yes. A few went back to their distractions.

“Okay, no problem. Bye then.”

I semi-purposefully turned around and walked off the train. My legs were shaking in the way they did back when I was scared of public speaking, my knees feeling like rounding errors in their control code was threatening to make them send my shin in all sorts of nasty directions, while the tensed muscles in my leg seemed to hold it all together. The world did not end. Weird.

I felt like throwing up. Luckily, the sensation was blocked in my chest by a collision with some coldhot coming from my arms. They seemed to be really in control. My chest just felt sort of warm.

A horde of thoughts about what I could have done differently accosted me. “You should've focused on individuals, made direct eye contact no that would be creepy”, “Why did you do this on a metro? People don't talk to other people here, just go to UMD or a party or something and you'll win so hard”, “I know you're proud that you actually followed through, but you should actually think at all beforehand to increase the probability of success”, "Come on it wasn't even that big of a deal, you just said something weird to about 15 people at once, I bet most of them didn't hear you anyway". I thanked them for their contribution, and dismissed them.

My heart sank a little, but not as much as my first rejection. My pride caught it -- I had done exactly what I had intended to do.

I glanced around the terminal and smiled at a few maintenance workers. I sat down and pulled out my kindle.

It was quite the rejection.

You're talking with someone you like, and they ask you what you mean by rationality, or why you keep going to LessWrong meetups. Or you meet someone who might be interested in the site.

What do you say to them? If you had to explain to someone what LW-style rationality is in 30 seconds, how would you do it? What's your elevator pitch? Has anyone had any success with a particular pitch?

My Current Pitch:

My current best one, made up on the spot, lacking any foreplanning, basically consists of:

"Basically, our brains are pretty bad at forming accurate beliefs, and bad in fairly systematic ways. I could show you one, if you want."

Playing the triplet game with them, then revealing that the numbers just need to be ascending

Upon failure, "Basically, your brain just doesn't look for examples that disprove your hypothesis, so you didn't notice that it could have a been a more general rule. There are a bunch of others, and I'm interested in learning about them so that I can correct for them."

My Thoughts on That:

It's massively effective at convincing people that cognitive biases exist (when they're in the 80% that fails, which has always been the case for me so far), but pretty much entirely useless as a rationality pitch. It doesn't explain at all why people should care about having accurate beliefs, and takes it as a given that that would be important.

It's also far too dry and unfun (compared to say, Methods), and has the unfortunate side effect of making people feel like they've gotten tricked. It makes it look non-cultish though.

I suspect that other people can do better, and I'll comment later with one that I actually put thought into. There's a pretty good chance that I'll use a few of the more upvoted ones and see how they go over.