Thinking Fast & Thinking Slow

Above is a brief summary presentation on Thinking Fast & Slow. This book review is part of a three part series on how humans learn.  Part 2 covers Cognitive Scientist Daniel Willingham’s excellent book Why Don’t Students Like School?  And Part 3 looks at current brain based learning trends. 

“Know Thyself” 

The inscription of Temple of Apollo at the Oracle of Delphi 

You are not so smart” is the title of a popular psychology blog that takes pleasure in revealing the many ways our evolved physical brains trick us into thinking we are rational reasoning creatures. Well after reading Thinking Fast & Slow by  I can certainly attest that I don’t feel very smart anymore, or at least, not very rational.  I found myself nodding along to anecdote after anecdote: “yep I’ve made that fallacy.  Yep, that one too”.  

At first I found Kanehman’s work a little disconcerting, but on the bright side, it’s not my fault that I am a lazy thinker—I was programmed that way!  We all are—and for good evolutionary reasons.  It turns out that thinking takes a lot of expensive energy—up to 20% of all calories!  And our brains really don’t like to do slow deliberate rational thinking (presumably because this is even more expensive, however scientists aren’t sure).  Consequently evolution has equipped us with shortcuts–heuristics and cognitive biases–mental tricks of intuition that save energy and work often enough to be very beneficial, but sometimes they can lead us astray.   Most disconcertingly, we usually don’t even know we do it.

Behavioral psychologist Daniel Kahneman received the 2002 Nobel Memorial Prize in Economic Sciences, with Vernon L. Smith, for their work on the psychology of judgment and decision-making.  I remember applauding the Noble committee when it awarded a prize to a psychologist.  I did’t actually know anything about Kahneman’s work but I have always been strongly critical of the behavioral assumptions that are foundational to classical economics.* Kahneman’s work has been fundamental to the developing field of behavioral economics.

In 2011, Kahnemen published Thinking Fast & Slow, a compendium the work he and his partner Amos Tversky (deceased) beginning in the early 1970s.  Needless to say it is a very dense work, despite being enjoyable and quite easy to read.  It actually took me several months to read, mostly because I had to stop every few pages to digest.  Today I am inclined to think that Thinking Fast & Slow–or at least the principal ideas–should be required reading for all educated adults.  In it Kahnemen succinctly explains the results of decades of psychology studies that show how our thinking actually seems to function.  They developed the idea that we have two systems of thinking, one fast, intuitively & impressionistically (system 1), and one slow, deliberately thoughtful and systematic (system 2). It turns out that most of us speed through life.

System 1, our fast system, works almost automatically.  When we speak our native language, or determine where a sound is coming from, or do simple equations, or drive (if we are experienced), we are activating our system 1.  Any skill that we have mastered to the point where we do not have to think about can become a system 1 response.  Many very complex actions that we do, like walking or running, are things we learned over decades.  System 1 is incredibly efficient but is also prone to mistakes (see tables below).  System 1 is also the root of terribly lazy thinking like making racial stereotypes.

System 2, our slow system, is what we think of when we normally refer to “thinking” it is when we are struggling to learn how to speak a foreign language, or drive a car for the first time or write a good essay (or a blog post). System 2 is hard work.  In fact we are only capable of doing it for limited periods of time before we succumb to decision fatigue and resort back to system 1 decision making.  I remember a few years ago reading Michael Lewis’s profile of Obama where Obama talked about never making a decision about what he wears so he doesn’t get tired.  This confused me at the time, but now I understand what he was talking about.  Thinking is hard.

System 1 Heuristics & Biases

Heuristics are mental rules of thumb that we subconsciously employ when making decisions.

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As a fairly well educated teacher I found some of the Cognitive biases identified by Kanehman to be particularly disheartening.  I have certainly found myself guilty of the narrative fallacy, particularly in history, I just love a good story!  My life as a contractor–and the consequent lack of business success–was pretty much defined by the planning fallacy.   The framing fallacy is one that teachers can use for success or failure; good priming helps students remember!

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I was very struck by Kahneman’s  discussion of the halo effect.  He found that he was treating students essays based on how he felt about the student’s overall work, so he began having students write their names at the end of the paper rather than at the beginning.  I have followed suit.  Some of these are biases that we may should have learned from a good statistics teachers, but they are all mental shortcuts that we should be aware of.  I will continue discussions for teachers in part 2 of my series on Daniel Willingham’s work.

“The attentive System 2 is who we think we are. System 2 articulates judgments and makes choices, but often endorses or rationalizes ideas and feelings that were generated by System 1” – Daniel Kanehman

In my opinion there is no other field where these insights have a greater ramification than in education. Programing effective intuition, and teaching students to recognize when that intuition is insufficient or astray should be the primary goals of a teacher. Furthermore the ability to access our own effectiveness as teachers requires a deep understanding of how humans actually learn.  One way to think about our job is to train students to turn difficult system 2 tasks–slow deliberate thinking, into system 1 responses.  This is why so many math teachers assign so much homework they are trying to program system 2 into system 1.   

A few years ago my favorite consistently contrarian writer Malcolm Gladwell wrote Blink, a pean to the awesome power of intuition.  Gladwell particularly extolled examples of experts who instinctually knew the right answers without even knowing why.  Through years of work (perhaps 10,000+ hours), they had trained their system 1 responses to be near perfect.   Our job as teachers is to do the best we can with students to do the same.  However that really requires that we also be honest with ourselves and recognize the mistakes that we make.  

I highly recommend Kahneman’s youtube talk here:


* Man has never much matched the behavioral model Homo Economicus, the utility maximizing rational agent that underlies classical economics, and I was very pleased to see the committee draw attention to that.

I was influenced by the following posts which also dissected Thinking Fast and Slow.  In fact I even borrowed the same quote from Kahneman from the blog post on To Notice and Learn.  (I recommend their much better written post, and in particular they give a great explanation of the loss aversion work which won Kahnmen the nobel prize).  I also very much enjoyed Freeman Dysons’ NYtimes review How to dispel your illusions.   Finally I love this fun picture.


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