This outline of the idea of dual processing is drawn from the book Thinking, Fast and Slow. The book covers other issues as well, but over half of it relates to the implications of System 1 and System 2 (and of course other researchers have responded to Kahneman's work) so for today I'm just going to cover the basics of the two systems and in the next Edition we will dig into the nuances.
The idea of more than one processing mode in the brain goes back to philosopher and psychologist William James, who drew a distinction between (in his conception) associative and true reasoning. While the modern idea is most associated with Daniel Kahneman the terms "System 1" and "System 2" were first coined by psychologists Keith Stanovich and Richard West in 2000.
Kahneman developed their ideas further and brought it to a wider audience, but many others have worked on different aspects. We'll start with Kahneman's definitions:
• 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.
He also makes a big point in the book that these are metaphors, not actual brain structures
In his book, Kahneman uses a picture of a face to demonstrate how System 1 can immediately interpret a face, see the emotion in it and extrapolate out in an instant the probable next actions of the person. His point is not the accuracy of the interpretation or prediction, but the speed and automatic nature of it.
He compares this to how for most people, the arithmetic multiplication 17 x 24 brings a very different reaction from the brain. Typically System 1 will tell you that you do know how to do this, but for most of us (not all) that's about all. It might nudge us that we Instead, we we are in the realm of System 2 and we access our memory for instructions (probably acquired back in school!) about the steps needed to complete the calculation.
In some ways I was surprised to find how much of the book was focussed on System 1. He does, however say "When we think of ourselves, we identify with System 2, the conscious, reasoning self that has beliefs, makes choices, and decides what to think about and what to do." This links back well it seems to me to the discussion of Reasoning in a recent book review. Our psychological sense of self is rational, but it is powered much of the time by the "automatic" System 1.
He outlines the following list of example activities "in growing order of complexity" that System 1 undertakes. As well as being in the book, this is also present in the excerpt of the book in Scientific American magazine:
• Detect that one object is more distant than another.
• Orient to the source of a sudden sound.
• Complete the phrase “bread and . . .”
• Make a “disgust face” when shown a horrible picture.
• Detect hostility in a voice.
• Answer to 2 + 2 = ?
• Read words on large billboards.
• Drive a car on an empty road.
• Find a strong move in chess (if you are a chess master).
• Understand simple sentences.
• Recognize that a “meek and tidy soul with a passion for detail” resembles an occupational stereotype.
Regular drivers will note that System 1 can take quite a large part of the role of driving on busy roads too. But what is striking about this list is that human beings automate more than we were taught in school biology class. (It always seems worth remembering to me that the vital elements of physical life, breathing and digesting food are completely automatic.)
The System 2 list is equally instructive:
The highly diverse operations of System 2 have one feature in common: they require attention and are disrupted when attention is drawn away. Here are some examples:
• Brace for the starter gun in a race.
• Focus attention on the clowns in the circus.
• Focus on the voice of a particular person in a crowded and noisy room.
• Look for a woman with white hair.
• Search memory to identify a surprising sound.
• Maintain a faster walking speed than is natural for you.
• Monitor the appropriateness of your behavior in a social situation.
• Count the occurrences of the letter a in a page of text.
• Tell someone your phone number.
• Park in a narrow space (for most people except garage attendants).
• Compare two washing machines for overall value.
• Fill out a tax form.
• Check the validity of a complex logical argument.
I am again fascinated by some of the overlaps here. My childhood home phone number seems to me to come out when required (almost never these days) right from System 1. However, the key point here that is beyond the obvious role of System 2 (stepping through details) is that of paying attention. It is possible that the cost of paying attention explains some of Decision Fatigue (see Edition #007 and Edition #008).
For Kahneman overall, System 2 exists to supplement and sometimes restrain System 1. The multiplication example shows how System 2 is mobilised when we are confronted by something that System 1 cannot handle. It also can act as an overseer, monitoring and vetoing System 1 reactions - but doing so seems to take energy. Finally, we should remember not to get too deep into the separation, the systems very much are connected, as Kahneman says:
"In summary, most of what you (your System 2) think and do originates in your System 1, but System 2 takes over when things get difficult, and it normally has the last word."
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