Exhibit 03 · Wing of Judgment
A spinning wheel you know is random is about to move your estimate. Watch it happen.
well-replicated since 1974 · replicated across 36 labs in Many Labs 1
Step 1 — spin the wheel of fortune
The wheel is honest randomness. It has no memory and no opinion.
Remember that in a minute.
Step 2 — a quick question
What percentage of the United Nations' member states are in Africa?
Is it higher or lower than %?
Step 3 — your actual estimate
When people estimate an unknown quantity, they start from whatever number is lying around — even a number they just watched a roulette wheel produce — and adjust from there. The adjustment is never enough. In Tversky and Kahneman's original 1974 demonstration, a wheel rigged to land on 10 or 65 preceded this exact question about African states in the UN: the group that saw 10 gave a median answer of 25%; the group that saw 65 gave 45%. A meaningless number, witnessed for three seconds, moved estimates by twenty points.
Anchoring has since been replicated across dozens of labs (including the 36-lab Many Labs project), with judges, doctors, and real-estate agents all proving as movable as undergraduates. Knowing about it helps less than you'd hope. (The true answer, as of the mid-2020s: 54 of 193 member states — about 28%.)