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kahneman system 1 and system 2 thinking

Noble Laureate Professor Daniel Kahneman describes mental life as composing of two fictitious characters – SYSTEM 1 and SYSTEM 2. In his book ‘Thinking Fast and Slow,’ he explains in great detail about these 2 systems and how they affect our thinking.

According to Kahneman System 1 and System 2 thinking uses different processing within the mind altogether. In this article, the abilities, limitations, and functions of these 2 systems will be explained. Read on!


SYSTEM 1 Thinking 

System 1 is what Kahneman describes as Fast Thinking.


Kahneman writes: “The capabilities of System 1 include innate skills that we share with other animals. We are born ready to perceive the world around us, recognize objects, orient attention, avoid losses, and fear spiders.”

“System 1 has learned to associate between ideas; it has also learned skills such as reading and understanding the nuances of social situations.”

Moreover, System 1 takes over during emergencies and assigns priority only to self-protective actions. Imagine driving a car that unexpectedly skids on a slippery surface. You will notice that you responded to the threat before you became fully conscious of it, a characteristic of System 1.


  • Detecting an object as being more distant than the other.
  • Tying your shoelaces
  • Orienting towards the source of a loud noise
  • Complete the phrase “Salt and…”
  • Make a ‘disgust face’ when looking at a horrible picture
  • Detecting hostility in a voice
  • Answering a simple arithmetic problem. 2 + 3 =?
  • Reading words on a large billboard.
  • Driving a car on an empty highway
  • Understand simple sentences
  • Form associations – the capital of France?

Note that several of the mental actions required to do the tasks listed above are involuntary. You can’t refrain yourself from understanding simple sentences in your own language, or from orienting towards a loud unexpected sound. Nor can you prevent yourself from knowing that 2 + 3 = 5 or from thinking of Paris when someone mentions the capital of France.

One of the hallmarks of System 1, Kahneman tells us, is that the calculations, judgments, or associations made are passive, that is -they do not feel like something you did, but rather, it felt like something that happened to you.

To summarize: the basic experience of System 1 thinking is an automatic and passive experience.


SYSTEM 2 Thinking 

System 2 is referred to as Slow Thinking.

It is SLOWER, requires EFFORT, and happens CONSCIOUSLY and DELIBERATELY.

Kahneman tells us: “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.”

He further elaborates: “System 2 is the only one that can follow rules, compare objects on several attributes, and make deliberate choices between options. The automatic System 1 does not have these capabilities.

 System 1 detects simple relations (‘they are all alike,’ ‘the son is much taller than the father’) and excels at integrating information about one thing. However, it does not deal with multiple distinct topics at once, nor is it adept at using purely statistical information.”

System 2 has one distinct characteristic: which is that it requires attention and can be disrupted when attention is drawn away.

 As Kahneman clarifies, System 2 is merely a supporting character who believes herself to be the hero.


  • Answer the problem: 16 × 23 =?
  • Attempting to hear the voice of a particular person in a noisy room.
  • Maintain a faster walking speed than is natural for you.
  • Looking for a relative with grey hair in a crowded train station.
  • Checking the validity of a complex logical argument.
  • Monitoring your own behavior in a social setting.
  • Counting the occurrences of the letter C in a page of text.
  • Remaining composed when you are angry.
  • Parallel parking in a narrow space (hopefully).
  • Comparing the overall value of 2 Smartphones.
  • Filling out a Tax Form.

Because these instances require you to do something that does not come ‘naturally,’ you will need to continuously exert effort in terms of sustained attention, to execute the tasks properly.


More on System 1 and System 2 Thinking …

The automatic operational capabilities of System 1, allow it to generate surprisingly complex patterns of ideas. However, only the slower System 2 can arrange and explain these patterns in an orderly, series of steps.

Note that system 1 and 2 are active whenever we are awake.

System 1 runs automatically whereas System 2 functions in a comfortable low-effort mode.

However, when System 1 runs into difficulty, it will call on System 2 for more detailed and specific processing. In other words, System 2 will spring into action when you perceive an event to have violated the model of the world that System 1 maintains.

In that world, lamps do not jump, and cats do not bark!

Now that you’re familiar with the distinctions between System 1 and System 2 thinking, it’s important to keep in mind that both the systems serve their purpose to help us function optimally. Some tasks are better suited for System 1, whilst others require us to focus more and utilize System 2.

It would be silly if after every time whilst tying your shoelaces (a task associated with System 1) you would think to yourself whether or not it was the best way to do it (System 2).

On the other hand, deciding to invest in buying shares of a car company based on how you feel about the cars and the company in general (System 1) would be unreasonable. You would be better off by considering its financial health, or taking into account price and valuation, and researching the current and projected profitability of the stocks (a System 2 task).

In the former scenario, you’re attempting to utilize System 2 for a task best left to System 1 (tying your shoelaces). Whilst in the latter, you’re relying on your gut feeling (System 1), instead of conducting due diligence before investing in the company’s stocks –a System 2 activity.  

The Cost of Intellectual Laziness

There are tasks that only System 2 can perform with a degree of reliability and accuracy. Furthermore, because laziness is part of our nature -an over-dependence on System 1 can lead to bad decisions, poor judgments, which can be costly.

The reason behind this, Kahneman writes, is because “System 1 has biases; systematic errors that it is prone to make in specified circumstances. It sometimes answers easier questions than the one it was asked, and it has little understanding of logic and statistics.”

Here’s a list along with descriptions of some of the more common cognitive biases that we are prone to, which can distort thinking and pave the way for sub-optimal decision making:

 1] Substitution: When presented with a difficult question, we tend to substitute it for an easier question, and answer accordingly.

For example, when asked “How happy am I with my life these days?” We will often substitute that for an easier question, that is –“What is my mood right now?”

 2] The Availability Heuristic: This is the tendency for people to predict the probability of an event occurring, based on how easily an instance or example comes to mind.

For instance, an investor may judge the quality of an investment, solely on information that he saw on the recent new, whilst ignoring other relevant facts.

3] Correlation is Not Causation: It is a fact that ice cream sales have a direct correlation with the number of sunglasses sold, but does that mean one causes the other?

You guessed right, they don’t! However, one of System 1’s tendencies is to attribute a cause-and-effect relationship between 2 variables simply by observing a mere correlation between them.

Thus, if two variables correlate, it does not mean that one causes the other.

 4] Confirmation Bias:  This is the tendency to seek information which confirms our previously held beliefs and preconceptions whilst ignoring information which contradicts them.

5] Anchoring Bias: The tendency to rely too heavily on an initial piece of information which acts as an unconscious psychological benchmark, which influences the final decision.

 6] Ignoring Statistics: Kahneman writes, Statistical thinking derives conclusions about individual cases from properties of categories and ensembles. Unfortunately, System 1 does not have the capability for this mode of reasoning; System 2 can learn to think statistically, but few people receive the necessary training.”

These are just some of the mental illusions that System 1 is prone to. In ‘Thinking Fast and Slow,’ you’ll find a thorough list of these biases along with explanations in how they affect our ability to make decisions and judgments.

Despite a Faulty System 1 and a Lazy System 2, How Does One Improve Their Thinking?

 “…we can be blind to the obvious, and we are also blind to our blindness.” – Daniel Kahneman

Here’s a short excerpt from Kahneman’s book, where he advices how one can improve their thinking:

 “The short answer is that little can be achieved without a considerable investment of effort. As I know from experience, System 1 is not readily educable. Except for some effects that I attribute mostly to age, my intuitive thinking is just as prone to overconfidence, extreme predictions, and the planning fallacy as it was before I made a study of these issues. I have improved only in my ability to recognize situations in which errors are likely.

We would all like to have a warning bell that rings loudly whenever we are about to make a serious error, but no such bell is available. Furthermore, cognitive illusions are generally more difficult to recognize than perceptual illusions.

The way to block errors that originate in System 1 is simple in principle: recognize the signs that you are in a cognitive minefield, slow down, and ask for reinforcement from System 2.”