Thinking, Fast and Slow

Book Review

Section 1:

In 1969, a chance exchange between psychologists Daniel Kahneman and Amos Tversky made them fascinated with why people are not intuitive statisticians. They began brainstorming intuitive judgments and streamlining them with experimental data. Thus was birthed in a small café in Jerusalem, a game changer, which redefined the thinking of how we think by establishing the psychological foundation of the traps and pitfalls in judgment and decision making caused by predictable intuitive biases.

They realized that the brain has dual modes of thinking. While System 1 is fast and creates an insuppressible allusion in our brain, System 2 is slow and requires careful deliberation that tends to stress the brain. If System 2 gives into System 1’s impulses, it results in a multitude of heuristics or assumptions made by System 1. These heuristics can be summarized by understanding the thought-process behind a yes-no decision.

If the problem is linked to the ideas we already believe in, we are likely to be convinced by the familiarity into making an intuitive decision. This is called cognitive ease.  Moreover, while trying to find a confirmation for this decision, we may overlook any counterclaims and only look for supporting arguments via system 1 intuition.

If the logical linkages are still missing or ambiguous, our intuition may also generate coherent stories and connections to justify and fit it into a normal view of the world. However, in case the problem is too complex, our subconscious may also substitute it with an easier problem. This is because we dislike uncertainty and wish for everything to make sense.

We also dislike losing more than we like winning. Therefore, if the decision is related to investment, we try to avert losses, often resulting in loss of profitable gambles. In fact, we also keep a risk catalog for emotions. For instance, spouses in abusive marriages often do not seek divorce because they do not want to risk feeling like a failure. They overestimate the risk and ignore the aggregate gain.

The book illustrates many such theories that show how our emotional frame of mind and casual explanations predicted using weak evidence and narrow thinking, result in cognitive illusions.


Section 2:

A major part of the book is premised on the “Priming Effect”. This effect explains how being exposed to a particular idea urges our subconscious to recall associated ideas. For instance, if we’re thinking about food, we’d fill the blank in SO_P to make soup rather than SOAP. This theory was developed further through two experiments, the ideomotor experiment and the Lady Macbeth experiment.

The first experiment, conducted by psychologist John Bargh, asked university students to make four-word sentences from the set of words “He finds it yellow instantly”. Half the students made words related to the elderly such as “wrinkle”, “Florida” and “forgetful”. All the students were then asked to move to another hall. It was observed that the walking speeds of the aforementioned segment of students were significantly slower than the rest. This effect, dubbed the Florida effect, had two stages of priming; priming the thoughts towards old-age and priming the behavior as per the thoughts.

This phenomenon of priming human behavior with an idea is also known as the ideomotor effect. It was subsequently proved to be reversible by a study which made students walk at one-third of their normal speed, following which they were quicker to recognize the words related to old-age.

To this effect, I have observed that smiling makes us feel happy while feeling happy makes us smile. This is because we have been conditioned to think that a smiling individual is happy. And both, the feeling and the action, urge the subconscious to pull out ideas related to happiness. It’s a reciprocal priming effect.

Similarly, if we read about murder and terrorism in the newspaper, we will be more likely to recall a gruesome TV show like the “Game of Thrones” rather than a comedy like “Friends”.

The second experiment discussed in relation to priming is what I call the Conscience Attack. The author observed that an “honesty-box” in the kitchen of a British university labeled with only the prices of beverages remained quite empty. But for a period of ten weeks, a banner with images began being posted on the box. The weeks with the image of eyes had the highest contributions because it made the people feel that they were being watched and nudged their conscience into paying.

Similarly, the author conducted another experiment which forced people to lie to an imaginary person. Those who lied on the phone later preferred a mouthwash, while those who lied via e-mail preferred soap. This shows how cleansing the “stained” part of the soul can psychologically prime one into feeling less guilty. Quite aptly, it has been labeled the Lady Macbeth effect.

Initially, I was skeptical since I thought that soap may have been preferred because typing makes fingers dirty while mouthwash may have been used to refresh the mouth after prolonged speaking. However, I changed my opinion after recalling how victims of sexual assault often inflict bruises upon their body while trying violently cleanse the feeling of being violated. Lady Macbeth effect indeed.


Section 3:

The book gave me a novel insight into engineering and economics. I was able to append newer explanations to theories such as the law of diminishing marginal utility.

One such explanation could be the Miswanting Effect whereby initial excitement can make us wish more for a product than our actual want, but as the focusing illusion of “excitement” erodes, we tend to purchase less. It explains the importance of marketing in elongating the period of “excitement”.

Another example would be finding the shortest path connecting all the nodes in a network. Initially, my intuition made me branch from a central node into a star network. However, after using system 2 to validate it I realized why Prim’s method would be a more accurate algorithm. As an engineer, I now realize the importance of not trusting my instincts without rigorous proof.

I have also observed that in this course we have always statistically operated upon a large range of data. This decision could be explained as an effort to avoid the law of small numbers whereby a smaller data sample is simpler to process.

To conclude, while many ideas matched my prior observations and made the book seem pedantic, I later appreciated their validation through systematic experimentation. Given that I am highly intuitive, it also made me more self-aware of my daily judgments and taught me to evade biases.


Related poems

While I haven’t specifically written any poems inspired by the book, the following seem to be close matches:



Kahneman, D. (2011). Thinking, Fast and Slow. Retrieved from