Narrative Bias
Narratives reduce complex information into simpler, more memorable stories, but this can cause people to overestimate the probabilities of events within the story, as seen when readers assign high probabilities to multiple suspects in a detective novel.
THE IDEA
A Better Way to Die
To view the potency of narrative, consider the following statement: “The king died and the queen died.” Compare it to “The king died, and then the queen died of grief.” This exercise, presented by the novelist E. M. Forster, shows the distinction between mere succession of information and a plot. But notice the hitch here: although we added information to the second statement, we effectively reduced the dimension of the total. The second sentence is, in a way, much lighter to carry and easier to remember; we now have one single piece of information in place of two. As we can remember it with less effort, we can also sell it to others, that is, market it better as a packaged idea. This, in a nutshell, is the definition and function of a narrative.
To see how the narrative can lead to a mistake in the assessment of the odds, do the following experiment. Give someone a well-written detective story—say, an Agatha Christie novel with a handful of characters who can all be plausibly deemed guilty. Now question your subject about the probabilities of each character’s being the murderer. Unless she writes down the percentages to keep an exact tally of them, they should add up to well over 100 percent (even well over 200 percent for a good novel). The better the detective writer, the higher that number.
When to use it
When evaluating investment opportunities, be wary of compelling narratives about a company's future that may inflate its perceived likelihood of success.
In legal settings, jurors may assign high probability to a suspect's guilt if the prosecutor's narrative is compelling, even when evidence is weak.
When making predictions, consider whether a story makes an event seem too plausible and adjust your probability estimates accordingly.
FROM THEORY TO EVERYDAY LIFE
In practice
Forster's King and Queen
Comparing 'The king died and the queen died' to 'The king died, and then the queen died of grief' shows how adding a causal narrative reduces the dimensionality of information, making it easier to remember and transmit.
Detective Novel Probabilities
Taleb proposes asking a detective-story reader for each suspect’s probability of being the murderer, then checking whether the total exceeds 100%. For this check, the alternatives must be mutually exclusive and cover the possibilities under consideration. The passage proposes the exercise rather than reporting study results.
A MOMENT TO REFLECT
Put it to work.
How can you detect when a narrative is influencing your probability assessment?
In what ways do news stories shape your perception of risk?
Can you identify a time when a compelling story led you to overestimate an outcome's likelihood?
CONTINUE THE CONVERSATION
Source texts
- The Black Swan The Impact of the Highly Improbable With a new section On Robustness and Fragility (Nassim Nicholas Taleb)