Concept · Cognitive Bias: Decision-making and judgment biases
Ambiguity effect
Origin: Ellsberg, 1961
Biological Parallel
Given a choice between a known berry patch (30% of bushes have fruit) and an unfamiliar patch (unknown fruiting rate), animals prefer the known patch even if the unknown might be better. Ambiguity signals unknown dangers—unfamiliar patches could harbor predators, toxins, or competitors. The ambiguity effect is informational risk aversion: known probabilities permit preparation; unknown probabilities mean uncontrolled exposure. Better the devil you know.