Book Review: Thinking, Fast and Slow - Part 2
1. The science of availability
The availability heuristic (mental shortcut) substitutes one question for another.
In a famous study couples were asked how large was their personal contribution to keeping their place tidy in percentages. Both contributions added up to more than 100%. Both spouses remember their own individual efforts and contributions more than those of the other.
Many members of a collaborative team feel they have done more than their share but its useful to know that you are likely to have that feeling even when every other member of the team feels the same way.
2. The psychology of availability
Norton Schwarz led an intriguing study on the availability heuristic in the 90’s.Participants were asked to list six instances where they behaved assertively, to evaluate how assertive they were.
The study observed that the task of listing the instances enhanced the judgement of the trait by two different routes:
The number of instances retrieved
The ease with which they come to mind
The experiment also asked a cohort of people to list twelve instances. Most people struggled to come up with the last few to make up twelve.
The study proved that regardless of how many instances retrieved, the ease (or difficulty) of retrieval was the bigger impact on the judgement of the trait.
Next, they tested the theory further, they told participants they would hear background music during the task and the background music would affect the performance. So participants expected a disruption to performance.
When prior warned of the fluidity of retrieval, the availability heuristic was less prevalent in the task of judging assertiveness. It was used less as a substitutive answer.
3. Availability biases
Examples in which people are affected more strongly by the availability heuristic (which tends to be guided by system 1):
When they are engaged in another effortful task at the same time
Score low on the depression scale
A knowledgeable novice on a task, rather than a true expert
When they score high on the scale of faith in intuition
If they are (or are made to feel) powerful
4. Availability, emotion and risk
Paul Slovic, Sarah Lichtenstein and Baruch Fischoff carried out a study on availability bias. They researched public perceptions of risk asking participates to indicate the more frequent cause and and estimated ratio of the following:
Tornadoes were seen as more frequent killers than asthma, although asthma actually causes 20 times more deaths
Death by disease and death by accidental death were seen as equally as likely, even though death by disease is 18 times more likely
Death by accidents was judged to more than 300 times more likely than death by diabetes, even though the true ratio is 1 accidental death for every 4 deaths by diabetes.
Something was becoming clear via the survey, estimates of causes of death are warped by media coverage. The world in our heads is not a precise replica of reality; our expectations of the frequency of events are distorted by the prevalence of and emotional intensity of the messages that we are exposed to.
5. The affect heuristic is an instance of substitution
Whereby the answer to easy questions (e.g. how do I feel about it?) serves as the answer to much harder questions (e.g. what do I think about it?)
6. How this substitution affects our lives
This heuristic simplifies our lives by creating a world that is much tidier than in reality. In the real world there are painful trade-offs between benefits and costs.
Good technologies have few costs in the imaginary word we inhabit, bad technologies have no benefits, and all decisions are easy.
7. Probability
Daniel Kahneman considers that in all the years he’s spent asking questions about probability of events, nobody has raised a hand and asked “what do you mean by probability?”
He surmises that people are not stumped because people generally do not try to judge probability as statisticians and philosophers do.
Instead the word acts as a mental shotgun, evoking answers to easier questions, such as predictability by representativeness.
8. Predictability by representatives
Micheal Lewis bestselling Moneyball is an example of how predictability by representativeness is not statistically optimal.
The manager of the Oakland A’s makes the unpopular opinion of ignoring his scouts assessment of players based on build and look but instead by their statistics of past performance.
The players the A’s picked were inexpensive, because other teams had rejected them in part for not looking the part. The team soon achieved excellent results at low cost.
9. In life, we are regularly faced with conflicts between the intuition of representativeness and the logic of probability.
10. When you specify a possible event in greater detail you can only lower its probability:
In an experiment, audiences were given a list of eight possible scenarios for a person:
Linda is a teacher in elementary school
Linda works in a bookstore and takes yoga classes
Linda is active in the feminist movement
Linda is a psychiatric social worker
Linda is a member of the league of women voters
Linda is a bank teller
Linda is an insurance salesperson
Linda is a bank teller and is active in the feminist movement
Audiences were asked to rank these findings, and people come to the conclusion that Linda fits the idea of a feminist bank teller better than the fits the stereotype of bank teller. The sterotypical bank teller is not a feminist activist, and adding that detail to the description makes for a more coherent story.
There is a logical relation between the two scenarios. Think in terms of Venn diagrams, the set of feminist bank tellers is wholly included in the set of bank tellers, as every feminist bank teller is a bank teller.
Therefore, the probability that Linda is a feminist bank teller must be lower than the probability of her being a bank teller!
The problem sets up a conflict between the intuition of representativeness and the logic of probability.