Update beliefs explicitly when new information arrives
Treat new information as a reason to state a revised probability, not as confirmation of the old one.
Why it works
Motivated reasoning causes people to accept confirming evidence uncritically and scrutinize disconfirming evidence heavily. Explicitly updating a stated probability when new information arrives counteracts this: it forces engagement with whether the new information actually moves the probability and by how much, rather than allowing the old position to persist through selective attention.
How to do it
- When new information arrives, ask: does this change my probability estimate? By how much?
- State the updated probability explicitly, not just the direction of change.
- Distinguish between new information (genuine update trigger) and noise (random fluctuation without evidential weight).
- Track how often new information actually moved your estimate — this calibrates your updating sensitivity.
Evidence
Bayesian updating is the normative model for belief revision under uncertainty. Research on belief perseverance and confirmation bias shows people update less than the evidence warrants; interventions that force explicit probability statements improve updating. (mechanistic)
Bayesian updating is prescriptive; human updating is imperfect even with training, and overconfident updating (moving too much on weak evidence) is also a documented error.
Sources
- Lord, Ross & Lepper (1979), belief perseverance after evidential challenge, Journal of Personality and Social Psychology
Common mistake
Saying "that changes things" without specifying how your probability changed — vague acknowledgment of new information is not an update.
Practice this with IX Coach
7 days free, then $40/month (~$1.30/day).
More practices for Thinking in Bets
- Separate the quality of the decision from the outcome
A good decision can produce a bad outcome, and a bad decision can produce a good outcome — do not confuse them.
- Think in probabilities, not certainties
Replace "I think this will happen" with "I think there is a 70% chance this will happen."
- Run a premortem before committing
Imagine the decision has already failed — then ask why.
- Check the outside view before trusting the inside view
Ask how similar situations have gone before trusting your story about this specific situation.
- Find a truth-seeking group that argues with you
Surround yourself with people whose job in the relationship is to challenge your reasoning, not validate it.
Related concepts
- Thinking, Fast and Slow, Made Usable
Two systems, the biases they create, and when to slow down
- Hanlon's Razor: Never Attribute to Malice What Stupidity Can Explain
The charitable-attribution heuristic and why it usually serves you better
- Circle of Competence
Know what you know, know what you do not know, and act accordingly
- Second-Order Thinking: And Then What?
Tracing consequences of consequences, the way Howard Marks does