Review: Thinking, Fast and Slow, by Daniel Kahneman

Russ Allbery eagle at eyrie.org
Fri Aug 23 21:31:54 PDT 2019


Thinking, Fast and Slow
by Daniel Kahneman

Publisher: Farrar, Straus and Giroux
Copyright: 2011
ISBN:      1-4299-6935-0
Format:    Kindle
Pages:     448

Daniel Kahneman is an academic psychologist and the co-winner of the
2002 Nobel Memorial Prize in Economic Sciences for his foundational
work on behavioral economics. With his long-time collaborator Amos
Tversky, he developed prospect theory, a theory that describes how
people chose between probabilistic alternatives involving risk. That
collaboration is the subject of Michael Lewis's book The Undoing
Project, which I have not yet read but almost certainly will.

This book is not only about Kahneman's own work, although there's a lot
of that here. It's a general overview of cognitive biases and errors as
explained through an inaccurate but useful simplification: modeling
human thought processes as two competing systems with different
priorities, advantages, and weaknesses. The book mostly focuses on the
contrast between the fast, intuitive System One and the slower,
systematic System Two, hence the title, but the last section of the
book gets into hedonic psychology (the study of what makes experiences
pleasant or unpleasant). That section introduces a separate, if
similar, split between the experiencing self and the remembering self.

I read this book for the work book club, although I only got through
about a third of it before we met to discuss it. For academic
psychology, it's quite readable and jargon-free, but it's still not the
sort of book that's easy to read quickly. Kahneman's standard pattern
is to describe an oddity in thinking that he noticed, a theory about
the possible cause, and the outcome of a set of small experiments he
and others developed to test that theory. There are a lot of those
small experiments, and all the betting games with various odds and
different amounts of money blurred together unless I read slowly and
carefully.

Those experiments also raise the elephant in the room, at least for me:
how valid are they? Psychology is one of the fields facing a
replication crisis. Researchers who try to reproduce famous experiments
are able to do so only about half the time. On top of that, many of the
experiments Kahneman references here felt artificial. In daily life,
people spend very little time making bets of small amounts of money on
outcomes with known odds. The bets are more likely to be for more
complicated things such as well-being or happiness, and the odds of
most real-world situations are endlessly murky. How much does that
undermine Kahneman's conclusions? Kahneman himself takes the validity
of this type of experiment for granted and seems uninterested in this
question, at least in this book. He has a Nobel Prize and I don't, so
I'm inclined to trust him, but it does give me some pause.

It didn't help that Kahneman cites the infamous marshmallow experiment
approvingly and without caveats, which is a pet peeve of mine and means
he fails my normal test for whether a popular psychology writer has
taken a sufficiently thoughtful approach to analyzing the validity of
experiments.

That caveat aside, this book is fascinating. One of the things that
Kahneman does throughout, which is both entertaining and convincing, is
show the reader one's brain making mistakes in real time. It's a
similar experience to looking at optical illusions (indeed, Kahneman
makes that comparison explicitly). Once told what's going on, you can
see the right answer, but your brain is still determined to make an
error.

Here's an example:

  A bat and ball cost $1.10.
  The bat costs one dollar more than the ball.
  How much does the ball cost?

I've prepped you by talking about cognitive errors, so you will
probably figure out that the answer is not 10 cents, but notice how
much your brain wants the answer to be 10 cents, and how easy it is to
be satisfied with that answer if you don't care that much about the
problem, even though it's wrong. The book is full of small examples
like this.

Kahneman's explanation for the cognitive mistake in this example is the
subject of the first part of the book: two-system thinking. System one
is fast, intuitive, pattern-matching, and effortless. It's our default,
the system we use to navigate most of our lives. System two is
deliberate, slow, methodical, and more accurate, but it's effortful, to
a degree that the effort can be detected in a laboratory by looking for
telltale signs of concentration. System two applies systematic rules,
such as the process for multiplying two-digit numbers together or
solving math problems like the above example correctly, but it takes
energy to do this, and humans have a limited amount of that energy.
System two is therefore lazy; if system one comes up with a plausible
answer, system two tends to accept it as good enough.

This in turn provides an explanation for a wealth of cognitive biases
that Kahneman discusses in part two, including anchoring, availability,
and framing. System one is bad at probability calculations and relies
heavily on availability. For example, when asked how common something
is, system one will attempt to recall an example of that thing. If an
example comes readily to mind, system one will decide that it's common;
if it takes a lot of effort to think of an example, system one will
decide it's rare. This leads to endless mistakes, such as worrying
about memorable "movie plot" threats such as terrorism while
downplaying the risks of far more common events such as car accidents
and influenza.

The third part of the book is about overconfidence, specifically the
prevalent belief that our judgments about the world are more accurate
than they are and that the role of chance is less than it actually is.
This includes a wonderful personal anecdote from Kahneman's time in the
Israeli military evaluating new recruits to determine what roles they
would be suited for. Even after receiving clear evidence that their
judgments were no better than random chance, everyone involved kept
treating the interview process as if it had some validity. (I was
pleased by the confirmation of my personal bias that interviewing is
often a vast waste of everyone's time.)

One fascinating takeaway from this section is that experts are good at
making specific observations of fact that an untrained person would
miss, but are bad at weighing those facts intuitively to reach a
conclusion. Keeping expert judgment of decision factors but replacing
the final decision-making process with a simple algorithm can provide a
significant improvement in the quality of judgments. One example
Kahneman uses is the Apgar score, now widely used to determine whether
a newborn is at risk of a medical problem.

The fourth part of the book discusses prospect theory, and this is
where I got a bit lost in the endless small artificial gambles.
However, the core idea is simple and quite fascinating: humans tend to
make decisions based on the potential value of losses and gains, not
the final outcome, and the way losses and gains are evaluated is not
symmetric and not mathematical. Humans are loss-avoiding, willing to
give up expected value to avoid something framed as a loss, and are
willing to pay a premium for certainty. Intuition also breaks down at
the extremes; people are very bad at correctly understanding odds like
1%, instead treating it like 0% or more than 5% depending on the
framing.

I was impressed that Kahneman describes the decision-making model that
preceded prospect theory, explains why it was more desirable because it
was simpler and was only abandoned for prospect theory because prospect
theory made meaningfully more accurate predictions, and then pivots to
pointing out the places where prospect theory is clearly wrong and an
even more complicated model would be needed. It's a lovely bit of
intellectual rigor and honesty that too often is missing from both
popularizations and from people talking about their own work.

Finally, the fifth section of the book is about the difference between
life as experienced and life as it is remembered. This includes a
fascinating ethical dilemma: the remembering self is highly sensitive
to how unpleasant an experience was at its conclusion, but remarkably
insensitive to the duration of pain. Experiments will indicate that
someone will have a less negative memory of a painful event where the
pain gradually decreased at the end, compared to an event where the
pain was at its worst at the end. This is true even if the worst moment
of pain was the same in both cases and the second event was shorter
overall. How should we react to that in choosing medical interventions?
The intuitive choice for pain reduction is to minimize the total length
of time someone is in pain or reduce the worst moment of pain, both of
which are correctly reported as less painful in the moment. But this is
not the approach that will be remembered as less painful later. Which
of those experiences is more "real"?

There's a lot of stuff in this book, and if you are someone who (unlike
me) is capable of reading more than one book at a time, it may be a
good book to read slowly in between other things. Reading it straight
through, I got tired of the endless descriptions of experimental setup.
But the two-system description resonated with me strongly; I recognized
a lot of elements of my quick intuition (and my errors in judgment
based on how easy it is to recall an example) in the system one
description, and Kahneman's description of the laziness of system two
was almost too on point. The later chapters were useful primarily as a
source of interesting trivia (and perhaps a trick to improve my memory
of unpleasant events), but I think being exposed to the two-system
model would benefit everyone. It's a quick and convincing way to
remember to be wary of whole classes of cognitive errors.

Overall, this was readable, only occasionally dense, and definitely
thought-provoking, if quite long. Recommended if any of the topics I've
mentioned sound interesting.

Rating: 7 out of 10

Reviewed: 2019-08-23

URL: https://www.eyrie.org/~eagle/reviews/books/1-4299-6935-0.html

-- 
Russ Allbery (eagle at eyrie.org)              <http://www.eyrie.org/~eagle/>


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