Cognitive Psychology (PSYC 110) · Module 7 of 10
Heuristics & Biases in Judgment
The mental shortcuts that make quick judgments possible — and the systematic errors they produce.
The Availability Heuristic
- The availability heuristic judges the likelihood or frequency of an event based on how easily examples come to mind, which can be distorted by media coverage or vividness rather than actual statistical frequency.
Why do people tend to overestimate the risk of dying in a plane crash compared to a car crash, even though car crashes are statistically far more common?
Solution. Plane crashes receive vivid, extensive media coverage, making examples easier to recall, which — via the availability heuristic — leads people to overestimate their actual frequency compared to more common but less memorable events.
The Representativeness Heuristic
- The representativeness heuristic judges the probability of something belonging to a category based on how similar it is to a typical or stereotypical example of that category, often ignoring important statistical information like base rates.
Why might someone incorrectly judge a quiet, detail-oriented person as more likely to be a librarian than a salesperson, even if salespeople vastly outnumber librarians?
Solution. The person's traits seem representative of a stereotypical librarian, leading to a representativeness heuristic judgment; this ignores the base rate — the fact that there are far more salespeople than librarians overall.
Anchoring & Adjustment
- The anchoring and adjustment heuristic involves relying too heavily on an initial piece of information (the "anchor") when making estimates, and insufficiently adjusting away from it, even when the anchor is arbitrary or irrelevant.
In a classic study, participants who saw a higher randomly-spun number gave higher estimates for an unrelated question than participants who saw a lower number. What does this demonstrate?
Solution. It demonstrates anchoring and adjustment — the initial random number served as an anchor, and even though it was irrelevant, participants' estimates were pulled toward it, showing insufficient adjustment away from an arbitrary starting point.
Confirmation Bias
- Confirmation bias is the tendency to seek out, interpret, and remember information in ways that confirm one's existing beliefs, while ignoring or discounting contradictory evidence.
How might confirmation bias affect someone doing "research" to confirm a belief they already hold strongly?
Solution. They are likely to seek out sources that support their existing belief, interpret ambiguous evidence as supporting it, and more easily dismiss evidence that contradicts it, reinforcing the original belief regardless of its actual accuracy.
Check yourself
2 of this module's 5 quiz questions. Pick your answers, then check them in the app, with an explanation for every question.
1. What does the availability heuristic rely on to judge likelihood?
2. What does the representativeness heuristic ignore, that it shouldn't?