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Two Systems: Thinking Fast, and Slow Chapter 1 Summary. Part 1

Two Systems: Thinking Fast, and Slow Chapter 1 Summary. Part 1

Two systems?

Conscious decisions sometimes occur with you in a way that you’re unconscious about them. Such as biases which are a fault or an error of thinking, like the halo effect and impression forming, which are giving other traits to someone based on a single trait, for example we tend to see attractive people as intelligent.

For the intro part we get that this book will be about identifying errors of judgments and thinking, and how to avoid them or know about them when making choices.

The author of thinking fast, and slow was in Jerusalem and he knew a person by the name of Amos, he was considered as the most intelligent professor amongst them. One day they were debating If people are good intuitive statisticians and the result was that people lack intuitive statistic qualities, plus people and researchers are prone to follow researches that are lacking some clear or inadequate evidences, and they confirmed that with a study.

From the book: “Even statisticians were not good intuitive statisticians”.


The friendship and work ethics between the author and Amos has grown throughout the years. They’ve done many studies together, learning the human psychology of choice including intuitive thinking, biases and heuristic based decisions.

They had an article together named: Judgment Under Uncertainty: Heuristics and Biases. Explaining basically biases and heuristics.

Amos and the author certainly studied a lot about Judgment, choice, decisions, bias, and heuristics as of the theme of the introduction so far. Sadly, Amos died and that shocked me a bit. With the author gaining the noble prize later on alone.

In the intro also he tackled what he named an expert intuitive or the sixth sense, which is a sort of a magical power that we have as an instinct. The firefighter had told everyone to get out of the house without thinking or having an idea why, soon after indeed everything collapsed, that was an expert intuitive example that I admired. That power is actually an evolutionary instilled system in us, to make us react in the hard times or simply in casual times.

So intuitive thinking situations are a conclusion of many other past related thinking experiences, if you happen to get out of a situation because of intuitive thinking, is that because your brain has recognized and stored similar act experiences and it came out of your memory fast to solve the similar situation.

Part one: tow systems

The characters of the story: two systems

In this section the author shorty showed an image of a woman that has some face gestures, and she seems that she’s about to scream.

The second example was a multiplication of 17×24.

Between the two examples the author is trying to show how easy and fast we can think about certain situations, where in the other hand, how it’s hard and slow to process some other.

from the book:

System 1: operates automatically and quickly, with little or no effort and no sense of voluntary control.

System 2: allocates attention to the effortful mental activities that demand it, including complex computations. The operations of System 2 are often associated with the subjective experience of agency, choice, and concentration.


System 1 is somehow the originating power of system 2. As the author described how system 1 can interfere to develop system 2 in the intro. take the chess example: when certain hard stressing situations are solved quickly and without thinking “it seems”, but actually that was a loop of repetitive experiences that concluded to that fast act; simply a combination of system 1 and 2.

Examples of system 1:

  • Detect that one object is more distant than another
  • Orient to the source of a sudden sound
  • Answer to 2 + 2 = ?
  • Detect hostility in a voice

These indeed are innate skills. It is due to the reptilian part of the brain that we share with animals that we have these quick reactions, to survive. The part that we don’t share is actually the new cortex, which is the responsible of our consciousness and other abilities that we are unique in. such as solving mathematical queries.

And till now, I think also system 1 has two sections:

  • The involuntary part: it’s innate without any prior knowledge, such as sound detection, threat and danger reactions. Babies without any substantial knowledge, they can still form reactions to these situations.

  • An involuntary with knowledge part: it’s through repeated acquirement of knowledge in certain situations, like 2+2, it needed some explanation and efforts to get it, playing chess, language acquisition, and so on.

Later on, he explained how you can control somehow the system 1 by activating the system 2. Like the example of hearing a loud sound but not turning the head.

Examples of system 2:

  • Reading this book
  • Focus on certain things, such as a teacher, certain sound, certain smell…
  • Doing hard mathematical queries
  • Filling a tax forum or something related

This stuff requires some unnatural abilities, needs more effort and more attention to deal with them.

Author on System 2: intense focusing on a task can make people effectively blind.


The two systems are working together, the system 1 feeds the other one with constant signals like impression and intuition. When constantly the first system feeds the second one with what we said, it becomes a belief and get saved in the second system. The 2nd system will act upon the saved impressions which are turned into beliefs, so somehow in this case system 2 has become system 1 or overtook it.

When system 1 can’t answer and solve a problem, system 2 interferes and get’s more into details trying to fetch and solve it … whenever you run into a situation, briefly system one tries auto solutions, and when that takes a bit of time and effort to answer it, the second system gets activated as it’s a serious problem. When the problem of 17×24 runs to you, if you already know the answer then it’s a short auto reaction from you, but things get slow when you don’t actually know the answer and the slow system 2 engages.

System 2 keeps an eye on your behavior, when you’re sad, angry and facing emotions that needs some sort of reaction, it tries to maintain your calm. When you’re driving at night it tries and functions to keep you alert.

Sys2: Minimizes effort and optimizes performance.

Between the two systems there is a huge efficiency of performance, as system 1 does a great job most of the time with its good accuracy -although it has some biases- and that is extremely beneficial for the brain and its economy. System 2 gets on the way only when things are bit out of the system 1 hands.

In the conflict section we were given a task to follow.

thinking fast and slow and two systems

It’s a very tricky task and clearly needs system 2.

When trying to answer there is a certain resistance, as there is a certain conflict between the two systems, where one tries to auto read what you see and the second one was trying to resist it and stop it to stay relative to the task and say either uppercase/lowercase or left/right.

What we get from this?  System 2 can contain system 1 impulse reactions, and is the one in charge of self-control.

Other cited examples: trying to force attention on a book while you’re bored, that will lead you to return to the point where you lost the meaning of your reading.

The illusion part in this book is very enjoyable. Take a look at The Müller-Lyer illusion:

So, there are two lines and the head of arrow is attached one in a regular way and the other is reversed.

Now which one of the lines are more in length?

Clearly the above line, right?

No, they’re actually both equal in length, try to measure it and see.

That’s an illusion caused by impression and fast thinking.

Now if you see it, system 2 will know that the two lines are equally in length even when observing it, you see otherwise.

Cognitive biases and illusions are hard to overcome, the system one doesn’t get turned off at will and we need to cope with that. When you know the bias and identify it, then it may become a bit clearer and you can avoid the error due to the prior knowledge and syst2.

Attention and effort

the story hero is system 2, it’s an effort demanding lazy reliant on sys1 “to figure out some tasks”. But it’s a good self-control artist.

With mental effort, It’s about the Add-1 task. While setting a monometer to beat every 1 sec, try to have 4 cards of each containing 4 digits. The task is to get the card and read the digits loud, after 2sec try to add 1 to every digit you read. And it’s proven that it’s a hard task to do, how about the add-3 task????

This task showcases the mental effort it takes to do certain tasks. Hard tasks generally lead the pupils to widen, so basically, it’s an indicator.

For example, when trying to do a simple math multiplication, it dilates. When doing a hard multiplication problem, it dilates more.

I really enjoyed reading the lab experiment he did about giving some tasks “which are hard” to certain people and see their pupil reaction to the tasks on a wide screen on the corridor. It indeed confirmed that hard tasks require more opening to the pupils, where simple ones rest them to the normal size.

Other experiment, showed that while we concentrate on a task, its hard to notice other things interfering with the main one-or as he called it: people might get effectively blind doing hard tasks-, such as the invisible gorilla experiment and the one done by the author. Where focusing on the add 1 or 3 task, some letters were flashed rapidly to see if they noticed them. They were asked to focus on the main task while also reporting if the letter K was noticed. More when the task get’s hard, the reporting of the letter gets missed often.

System two works and focuses on the main topic and give it full attention, and it prioritizes certain acts from the rest, especially when things are threatening.

“As you become skilled in a task, its demand for energy diminishes”.

both systems are meant for survival more than anything else.

we tend to laziness, we’re built to try to economize the effort and energy, we always look for shortcut answers.

  • System 2 follow the rules where the first one doesn’t as it’s primitive

  • System 2 gets used to certain tasks, that later will allow us to perform them at lower effort and can enter in the system 1 to be automated

  • Going from a task that to another one is basically very effortful, especially when it’s under time pressure. So, time can impose effort, and without it effort will be less

  •  In slow thinking, the most effortful aspect is thinking fast as it requires more effort

The lazy controller

We are hardwired for laziness and low effort. We seek to answer everything in low effort economy to preserve our energy and minds.

The system 2 is lazy, when reading a book or doing a non-fun activity, we get bored. Also at the same time, this system tries it’s best to be in control of the situation and that’s what we call discipline.  As mike Tyson said: discipline is doing what you hate, but do it like you love it.

As the author said, when he was walking at a faster pace, there had to be a control or resistance from the system 2 to not slow down. It’s like when you’re running, to resist the urge of stopping and returning to the normal pace /or lazy pace/ system 2 takes control of that.

When system 2 is busy doing some hard tasks, the focus on self-control gets a bit out of control, the focus on behavior would be the work of system 1. As the author described, when you’re busy you’re likely to make selfish choices, use sexist language, and make superficial judgments in social situations.

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As he also concluded, that self-control needs attention and effort. And system two is the one responsible of regulating behavior and controlling thoughts.

Doing effortful things is tiring to the system 2 as it keeps working on resisting the urge to quit, or what’s known as ego depletion. Will power have a limit!

Glucose is a very important element when doing physical activities, right? How about mind activities then?

Our brain needs glucose to function properly and neatly, and in a task that required thinking and self-control, glucose levels indeed dropped. Ego depletion can be undone by pumping some glucose again to continue the other tasks and have another surge in will power.

So, fatigue and tiredness play a role in judgmental thinking results.

A bat and ball cost $1.10. The bat costs one dollar more than the ball. How much does the ball cost?

You’re answer and so does mine is 0.10$, that was intuitive thinking.

it’s wrong, it’s 0.5$.

We all followed the law of least effort in this one. Matter effect, more than 50% of Harvard students actually answered the incorrect answer of 0.1$.

Another fact, is that known facts doesn’t always come to us when we need them. Intelligence is to retrieve valuable needed information from the memory to solve a certain query.

Solving this type of let’s say puzzles is for more alert and intellectually active people.

Explaining the study of Walter Mischel, the correlation between self-control and intelligence.

People who tend to answer questions quickly without thinking, have lower control and they’re prone to system one controlling their lives, and also prone to instant gratification.

System 2 is the self-control, reasoning with some laziness.

The Associative Machine

What do you think of vomit?

You’re disgusted right? That’s the power of our associative mind. We had no control imagining vomit and reacting to it with disgust. That’s system 1 playing the role, and it’s unwillingly from your part. The connection made here activated the senses, from generating the image through a memory of vomit, to the final reaction of emotions. As mentioned in the book: you think with your body, not only with your brain.

priming is a strong factor now days in marketing. It is through the exposure of an early signal /such as a simple word/, that we form and initiates other ideas that are in reliance with the first one.

What first gets brought to your memory, will affect your next thoughts.

Saying the world “yellow” will generate the thought of a “banana”

Saying “cat” will often lead us to think about “mouse”, “cheese” and so on …

A study of John Bargh, called the priming experiment or Florida effect, where a set of students were given 5 words, which they need to form a sentence with 4 of them. The results showed that the 4 chosen words were all related to elderly. The experiment doesn’t end here, when the students were walking down the corridor, those who chose elderly, walked significantly slower than the others.

A word primed thoughts of old age, these thoughts primed a behavior that is associated with old age.

So, some changes in the environment, might lead to changes in behavior. The things around us, like colors, shapes and arrangements, have a direct link to our behavior.   

The effects of priming can also impact votes, charity initiatives and many more things in life. It’s a strong trick that can affect our behavior toward some situations.

Thinking Fast, and Slow is a great book that you should read…

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