What distinguishes fast and slow thinking? - Chapter 1

What is the distinction between System 1 and System 2? – Chapter 1

When looking at a picture of a blonde woman with an angry expression on her face, you immediately notice her having blonde hair and being angry. You get the feeling she is about to say something negative in a loud voice. This premonition of her future behaviour arose effortlessly and automatically. This is an example of ‘fast thinking’.

When looking at the mathematical problem 14 x 38, you quickly know it involves multiplication and you have a vague intuitive idea about the possible outcome. You quickly knew the answer ends with the number 2 and are sure 10.000 is not the right answer. However, the precise answer did not immediately come to mind. Solving the problem requires some time and taking several steps. You start with collecting your knowledge about multiplication from your memory, as learned in the early school years. Then you have to put this knowledge into practice, which takes some effort. This is an example of ‘slow thinking’. The computation involves both mental and physical work: it also leads to a higher blood pressure, an increased heart rate, tensed muscles and dilated pupils.

The modes of thinking are given various labels by psychologists. Kahneman refers to ‘System 1’ and ‘System 2’. System 1 operates fast, automatically, involuntary and without (hardly any) effort. System 2 involves effortful mental work, which requires concentration, making choices and agency. The feelings and impressions that effortlessly originate from System 1 are the main sources of the deliberate choices and explicit beliefs of System 2. Both systems have their own functions, abilities and limitations.

Examples of events that occur automatically and effortlessly (System 1) are:

  • Answer to 1 + 1 = ?

  • Hearing an unexpected sound: looking in the direction of the source.

  • Reacting to a threat before recognizing it.

The abilities of System 1 include skills which we also see in animals, like recognizing things and orienting attention. Other quick and automatic mental activities are the result of prolonged practice. System 1 involves learned skills (how to behave socially, reading) and learned associations (capitals of countries). Certain skills are acquired solely by specialized professionals. Learned skills require knowledge, which is stored in memory and can be accessed effortlessly and unintentionally. Some responses are entirely involuntary. You cannot stop yourself from knowing that 1 +1 = 2 or looking in the direction of a sudden sound. Others can be controlled but are usually done automatically. Controlling attention is an activity that fits both systems. Orienting to a sudden noise happens involuntary (System 1), but turns quickly into voluntary attention (System 2). Even if you manage to resist looking at the source, your attention was drawn to it. 

The various operations of System 2 share one feature: they all require attention and are disrupted when the attention is moved away. Examples are:

  • Bracing yourself for fireworks going off.

  • Maintaining a faster walking pace than your natural walking pace.

  • Focusing on the voice of a specific person in a noisy and crowded setting.

By programming the automatic functions of memory and attention, System 2 is somewhat able to alter the way System 1 works. Doing something that does not come naturally requires effort, you need to ‘pay attention’. Conducting several effortful activities at once is hard or impossible, because they interfere with each other. Solving a complex mathematical problem while crossing a busy road is very difficult. Talking to your partner while walking in a quiet park is not, because these activities are undemanding and easy. We all have some awareness of the limited capacity of attention.

The book ‘The Invisible Gorilla’ demonstrates how focusing intensely on a task can result into being blind to distractions. The writers instructed the participants to watch a clip of two teams passing a ball. One team was dressed in white, the other in black. The task was to count the amount of passes between the white players and paying no attention to the black team. After some time, a person in a gorilla suit enters the court. The gorilla was visible for 9 seconds and out of the thousands viewers, approximately half of them did not notice the gorilla. The task of counting and ignoring a team made them effectively blind. The viewers who did not notice the gorilla were sure it did not happen, they could not imagine failing to spot a gorilla on a sport court. The study demonstrates two important findings about the mind: people can be blind to the obvious and people can be blind to their own blindness.

When we are awake, both Systems are active. System 1 runs automatically, System 2 is usually in a low-effort mode. System 1 continuously generates feelings, intuitions, intentions and impressions for System 2. System 2 turns intuitions and impressions into beliefs, and impulses into conscious actions. System 2 normally adopts the suggestions of System 1 without modification. In general, you believe your impression and follow your feeling, which is fine in most cases. When System 1 encounters difficulties and does not provide an answer, it relies on System 2 to tackle the problem and provide the right answer. Surprises can also activate System 2. The gorilla experiment shows that some conscious attention is needed for detecting surprising stimuli. The surprise then activates and orients attention: staring and searching the memory for experiences that makes sense of the surprise. System 2 also monitors a person’s own behavior: the control that keeps people respectful when they are furious and alert when they are driving in the dark.

The division of mental work between System 1 and System 2 is very efficient: minimal effort and optimal performance. Their interaction is mostly successful, because System 1 usually provides accurate short-term pre3 dictions and models of familiar situations, and its initial responses to challenges are quick and normally appropriate. It has biases though: systematic errors that are likely to be made in certain circumstances. System 1 occasionally answers an easier question than the real question and has a limited understanding of statistics and logic. Another limitation is that you cannot turn System 1 off.

Conflicts between an intention of carrying out a task and an automatic (opposite) response occur regularly. You may remember a time when you tried not to stare at someone with an alternative hairstyle or when you forced your attention on boring homework. One task of System 2 is self-control: overcoming the impulses of System 1.

What are illusions?

The well-known Müller-Lyer illusion demonstrates the difference between an impression and a belief, as well as the autonomy of System 1. The two lines appear to be of different lengths, but have the same length. When looking at the image, you believe what you see: lines of different lengths. After measuring them, you (or your System 2) believe something else: you know that the lines have the same length, even though you still see a difference in length. You cannot turn System 1 off: you cannot decide to see two equal lines, despite knowing they are. Resisting the illusion requires learning to mistrust your impressions of the length of horizontal lines with arrows at the ends. This means recognizing the illusory pattern and remembering what the ‘catch’ is.

Some illusions are visual, others are cognitive. You cannot control feeling sympathy for someone who turns out to be a psychopath (System 1). This can be the automatic response to psychopathic charm. You can learn how to recognize the illusion and how to respond to it (System 2). Can cognitive illusions be overcome? Errors of intuitive thoughts are generally hard to prevent, since System 1 works automatically and turning it off is impossible. Some biases cannot be avoided, for instance when System 2 does not have a clue to the error. Even when a clue is available, preventing mistakes requires a lot of effort and we cannot constantly question our thoughts. System 2 is not fast nor efficient enough to replace System 1. The best option is learning to recognize circumstances in which mistakes are likely to occur and trying harder to prevent making significant mistakes when there is a lot at stake. However, recognizing our own mistakes is not easy. 

Kahneman uses the terms ‘System 1’ and ‘System 2’ as nicknames, because they are easier to say and take less space in our memory than ‘automatic system’ and ‘effortful system’. This is important, because any occupation of the working memory reduces our ability to think. He emphasizes that the systems are not real parts of the brain.

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