This post assumes basic knowledge of Type 1/Type 2 (System 1/System 2) categorization of mental processes.

Background (safe to skip)

After my first reaction of surprise (consuming perhaps a few months) to the topic of heuristics and biases, and after a few more readings on neuropsychology, I started re-visiting my first reaction in more detail. Should it really be surprising to learn that humans are not rational? Anyone with a basic connection with humans should easily see that we act irrationally in many situations – snap decisions, impulses, etc. – so what was the source of my surprise?

My best guess (knowing my limits of interpolation) was that my surprise was not a result of discovering that we’re irrational, but rather that there was a scientific approach in existence aiming at finding more about those irrationalities, and that results of predictable irrationality were appearing; that might eventually lead to unifying different biases under the same theory or source.

The notion of Type 1 and Type 2 thinking (or System 1 and System 2) is for me a theory that has the power to unify most of the biases and perhaps predict others. Kahneman’s Thinking Fast and Slow adopts such an approach, attempting to explain many biases in terms of Type 2 thought.

Now, this connected with a question I had back in college when I first learned about Artificial Neural Networks (I was lucky to chose this as a topic to research and give a lecture to my colleagues on): “if this is how the brain works, how does logical/rational thought emerge?”

To my understanding, Connectionism and the self-organizing patterning system that is the brain would naturally result in Type 1 thought as a direct consequence. The question that I had persistently is how can Type 2 thought emerge from this hardware? Jonah Lehrer’s The Decisive Point suggests that different brain areas are (more) associated with each type of thought, but essentially (until proven otherwise), I assume that they all rely on essence on a patterning process, a connectionist model.

Migration of Skills

We know that many skills start in Type 2 and migrate to Type 1 as we get more “experienced” in them. When we first learn driving, we need to consciously think of every move, and the sequence of steps to perform, etc. We consciously engage in executing a known sequence before changing lanes (for example): look at the side mirror, look at the side to cover the blind spot, decrease speed, etc.

As we get more driving experience, we stop to consciously process those steps, they become automatic, and we can even engage in other conscious processes while driving (e.g. having a conversation, thinking about a meeting you have later, etc).

I believe this is key to understanding the relation between both types of thought, since it provides a kind of interface between them, it provides a way to compare the same process executing by both systems.

Simple Type 2 operations

So, having to experimental apparatus at hand, I had only the weak instrument of personal interpolation plus childhood memory. Starting with a simple operation, I decided to attempt to compare its execution by both systems. The operation: single digit addition.

As a child, 3+2 could have multiple interpretations depending on previous education. Two examples might be: (1) visualize 3 apples, visualize 2 apples, count how many apples “appear” in working memory, and that gives you the answer. (2) Hold your fist in front of you, stretch out each finger, counting incrementally until you reach 3, then start new “thread” at 0, stretch more fingers counting until you reach 2, while also incrementing the first thread that stopped at 3 – the result then is the number reached by the first thread.

The above is an attempt at analyzing how a child, using Type 2 processes, would find the answer to 3+2; while a grown up will simply look at “3+2” and “5” would “magically” pop up in her brain.

Now, the question is: can we interpret the child’s processes as a sequence of Type 1 operations? The key operation here is counting, everything else can be easily understood as Type 1 operations (for example, a connection between the written number “3” and a picture of three apples can be understood as Type 1). What happens in the child’s brain as he counts? As children we had to learn to count, probably by just repeating the numbers in order over and over again, to form a connection between them. After some practice, the number 1 form a connection to 2, which is connected to 3, etc. in a linked list that extends as we learn more numbers. So, combining this connection, with a connection between a written number and its location in this list (3 is one element higher than 2), a child can use Type 1 to count.

So, roughly and abstractly, a child’s brain adding 3+2 might go in a sequence like this: the visions of “3” would fire a picture of 3 apples (a younger child might need to perform a counting pattern to reach that step, which would also later migrate to Type 1), “2” would fire two apples, a child then starts counting (each number connected to the next, and the context of counting enforces this connection), crossing out each apple with each fired number, until all apples are crossed out.

Now this introduces the following mental operation: visualizing apples and performing operations on this visual image while counting (like crossing out or marking each counted apple). My wild guess here is that this, again, is reducible to Type 1 operations resulting from basic teacher instructions on additions, including visual demonstrations.

Levels of Type 1 to 2 Migration

Now, as pointed above, a younger child might need to apply counting to convert “3” to an image of 3 apples. As the child grows, she might have formed (by practice) the direct grown-up pattern that translates the image of “3+2” directly to “5”. She will then use this to add a number like 13+12 – utilizing “3+2”, “1+1+1”, and the carry 1 visual patterns. So the child would apply Type 2 addition utilizing several skills recently migrated to Type 1. As the child grows up, more layers of processes would migrate to Type 1, and the current Type 2 operations would become more efficient as they rely on those migrated skills.

So, what I am saying here, my guess, is that there is no clear distinction between the two Types. That Type 2 operations are simple those that use a large number of Type 1 steps, and hence is slower, non-automatic (as they are slow, there is more time for other processes to stop them from completing, and hence they seem to be controlled), and effortful.

Which connectionism pattern will be used

Now probably a grown up still has all those accumulated skills in place. Seeing “3+2”, I still have the ability to apply the apple technique, and also to apply the direct connection between “3+2” and “5”. Which one I use, I suggest, is based on two probably algorithms:

  1. Size: I use what I call the “Largest Available Recognizable Pattern” (LARP). This means, how many patterns I need to invoke to come to a result. The brain then keeps invoking patterns from largest (less total number of patterns) to smaller, until a reasonable result is reached
  2. Time: this is based on the quickest pattern, which would usually be equivalent to the largest.


I totally confess that this is a wild guess, and an idea that is not at all fully developed. I am not aware if this idea had been suggested in a more mature way or not, so this is an attempt to mainly get feedback and resources from you, and perhaps to build it up into better structure.

The value of developing such a theory is that at some point it can be testable, and perhaps bring a better understanding of how we learn new skills, and more efficient ways to acquire and develop our skills.

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5 comments, sorted by Click to highlight new comments since: Today at 5:32 PM

I think the transition from Type 2 to Type 1 is very important for teaching.

When I was teaching, my students often complained why do they have to make exercises, if they already understand the topic. I felt that there are some good reasons, but I missed one of them. 1) Doing exercises is good for finding student's "bugs" in understaning the theory, if you think about exercises as unit tests in programming. 2) Doing many exercises means repeating the topic, and repeating leads to remembering. But the reason not obvious to me was: 3) Repeating converts the skill from Type 2 to Type 1 skill.

If a complex skill is built from dozens of subskills, it is necessary to have the subskills in Type 1 mode before trying to master the big skill. Otherwise the subskills will require so much attention that it is impossible to see the big picture and do the big task correctly. (As a programmer I would use a metaphor that Type 1 thinking is like a one-line function call, while Type 2 skill is like writing the algorithm. If I cannot use function calls, my algorithm's code will span across several screens, and will be a nightmare to edit or debug.) For example in mathematics it is difficult to explain solving quadratic equations to someone who still has problems with "why minus times minus equals plus" or "why minus in front of parenthesis changes inside all minuses to pluses and pluses to minuses"; because in the middle of explanation it will be necessary to explain these subtopics, and the the explanation is just too long and too complex to follow. Similarly it is difficult to explain algorithm design to someone who is still strugling with the "semicolon after each command".

So in order to teach complex skills, it is necessary to explain the subskills in Type 2, and then do enough exercises to convert them to Type 1. Otherwise students will understand the subskills, but will be unable to move to the big skill. I think this is real danger of some proposed school reforms -- less memorizing, more creative thinking; problem is, how could one creatively think about things they do not understand because they lack the basics.

And in my case, sometimes it's easier to understand the theory after I've done the application a number of times.

Another argument for drill is that it can make theory easier to remember.

However, it's also important to have some way of telling whether a person has done enough drill and is ready to move on.

This is interesting. But I'm not sure I followed it properly. Is there a post about Type 1/Type 2 mental processes? It might be good to link to it for those of us who need a refresher.

I like Kahneman's lecture here as it sums up the distinction nicely (thought it's a bit long) Edit: not sure if a post on LW exists though

Good, upvoted - your hypothesis is interesting. I tend to think of type 1 as the cognition/pattern recognition/thinking operation and type 2 as a way of sequentially combining type 1 sub-results. The sequentially operation involves working memory and therefore passes through consciousness and is slowed down. As soon as a group of type 1 operations fine-tune themselves to the point of not requiring working memory, they no longer generate type 2 operations.