Thinking, Fast and Slow: Part 1, Chapter 8 Summary & Analysis

System 1 continuously monitors what is going on outside and inside the mind, without specific intention and with little to no effort. These basic assessments play an important role in intuitive judgment, like the ability to distinguish friend from foe at a glance. Biologically, we are endowed with the ability to quickly evaluate how dominant a person is, and how trustworthy that person is.

This ancient mechanism has some modern influence: it affects how people vote. Kahneman’s colleague Alex Todorov showed his students pictures of the faces of political candidates who were running for office and asked the students to rate them on attributes like likeability and competence. The candidates whose faces had earned higher ratings of competence won in about 70% of the races for senator, congressman, and governor. Todorov demonstrated that people judge competence by these same two factors: strength and trustworthiness. The faces that exude competence have a strong chin and a slight, confident smile.

Political scientists followed up on these findings and determined that this automatic preference is likely to play a large role among uninformed voters and voters who watch a lot of television, but less so for others who are better informed and watch less TV.

In addition to understanding language, System 1 carries out basic assessments like computations of similarity and representativeness. Kahneman demonstrates this with a drawing. Two towers of blocks are immediately recognizable as having the same height, but it is more difficult to determine whether a set of those blocks laid flat would have the same height as those towers. In another figure, Kahneman presents a set of short lines, each with different lengths. It is easy for people to pick out one of the lines as being relatively average, but if we are asked what the total length of the lines is, we are unable to answer. We are good with intuiting averages but very poor with sums.

In an experiment, participants were asked about their willingness to pay for nets to cover oil ponds in order to save migratory birds from drowning. Different groups stated their willingness to pay to save 2,000, 20,000, or 200,000 birds. The average contributions of each group were about the same—between $78 and $88. The number of birds made little difference: instead people reacted to the image of a drowning bird they conjured.

Kahneman introduces another aptitude of System 1: matching across diverse dimensions. Kahneman introduces a fictional woman named Julie, who read fluently when she was four years old. He then asks, “How tall is a man who is as tall as Julie was precocious?” 6 feet is probably too little, but 7 feet is probably too much. It’s easy to pick a number, and that number will match that of other people in our cultural milieu. But Kahneman writes that later, we will observe the flaws in this mode of prediction.

System 1 constantly carries out computations, and often computes more than we want to or need to—which Kahneman calls the “mental shotgun.” In an experiment, people are asked to press a key as quickly as possible if they hear a pair of words that rhyme. They are much quicker to identify “vote” and “note” as rhymes than “vote” and “goat” as rhymes. Even though they are only listening to the words, they are still slowed down because System 1 computes the spelling.

In another study, people listened to a series of sentences with the instruction to determine as fast as possible if the sentence was literally true. Kahneman lists some sentences: “Some roads are snakes.” “Some jobs are snakes.” “Some jobs are jails.” All are literally false, but the second is more obviously false because the other two are metaphorically true. The intention to perform one computation evoked another and disrupted our performance.