A doctor estimates that a rare disease is common because she recently treated three cases. This judgment most likely reflects which heuristic?
ARepresentativeness — the cases are representative of the disease
BAvailability — recent vivid experiences make the disease seem more common than it is
CAnchoring — the doctor is anchored on the number three
DAffect — the doctor has an emotional reaction to the disease
The availability heuristic judges the probability or frequency of an event by the ease with which examples come to mind. Recent, vivid, or emotionally charged events are easier to recall and therefore judged as more frequent or probable. Three recent cases are highly available in the doctor's memory, leading to an overestimate of the disease's prevalence. The actual base rate of the disease is the relevant statistic, but availability substitutes ease of recall for statistical analysis.
Question 2 True / False
Heuristics are always harmful because they deviate from optimal statistical reasoning.
TTrue
FFalse
Answer: False
Heuristics are cognitive adaptations that trade accuracy for speed and efficiency. In many environments, they produce good-enough judgments with minimal cognitive cost. The representativeness heuristic often works because similar things do tend to belong to the same category; the availability heuristic often works because frequent events are indeed easier to recall. Biases arise at the margins — when the heuristic diverges from the statistical reality — but for everyday judgments under time pressure, heuristics are often the only feasible approach. Gigerenzer's ecological rationality program argues that heuristics can even outperform complex optimization in uncertain environments.
Question 3 Short Answer
What is the anchoring effect, and why is it particularly difficult to overcome?
Think about your answer, then reveal below.
Model answer: Anchoring occurs when an initial value (the anchor) disproportionately influences subsequent judgments, even when the anchor is arbitrary or irrelevant. People start from the anchor and adjust insufficiently toward the true value. It is difficult to overcome because anchoring operates through both deliberate adjustment (which people can try to correct) and selective accessibility (the anchor primes anchor-consistent information in memory), making it resistant to debiasing efforts. Even awareness of the bias does not eliminate it.
Tversky and Kahneman showed that spinning a wheel of fortune to generate a random number influenced estimates of the percentage of African countries in the UN — an obviously irrelevant anchor. Real-world anchoring affects salary negotiations (the first number named anchors the zone of possible agreement), legal judgments (damage award demands anchor jury deliberations), and retail pricing (suggested retail prices anchor willingness to pay). The dual-mechanism explanation (insufficient adjustment + selective accessibility) explains why anchoring is robust even among informed, motivated judges.