Sleeping Beauty Problem
Version 1.0.0 · Updated 2026-07-30
CORE DEFINITION
Sleeping Beauty participates in an experiment. A coin is tossed. If heads, she is woken once; if tails, she is woken twice (with memory erased each time). When she wakes, what probability should she assign to the coin having landed heads? (1/2 or 1/3?) Scaffold role: The difference in perspective on the sample space. It depends on whether you look from the perspective of the coin itself (God's eye view) or from the waking experience (subjective view). In business, this corresponds to the difference between unique users (UV) and page views (PV).
SCAFFOLDING EFFECT
Reduce cognitive load
The difference in perspective on the sample space. It depends on whether you look from the perspective of the coin itself (God's eye view) or from the waking experience (subjective view). In business, this corresponds to the difference between unique users (UV) and page views (PV).
Anchor fast decisions
The disagreement stems from the definition of the sample space. Thirder perspective: if tails, she is woken twice, so 2/3 of all wakings correspond to tails, hence the probability of heads is 1/3. Halfer perspective: the coin is fair, and waking provides no new information about the coin, so the probability remains 1/2. The essence is whether to use the event itself or the subjective experience/observation count as the sample.
MINIMUM ACTION
In progress 0/2Practice this model in one real situation:
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Source support: Explicit
- zh.wikipedia.orghttps://zh.wikipedia.org/wiki/%E7%9D%A1%E7%BE%8E%E4%BA%BA%E9%97%AE%E9%A2%98verified
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