 Probability Weighting. Finally, for known exogenous probabilities, people do not calibrate their subjective probabilities by direct inference (Levi 1977), but instead systematically underweight high-probability events and overweight low-probability events, with a cross-over point of approximately one-third  (Figure 1b).  Thus, changes in very small or very large probabilities have greater impact on the evaluation of prospects than they would under expected utility theory. People are willing to pay more to reduce the number of bullets in the chamber of a gun from 1 to 0 than from 4 bullets to 3 in a hypothetical game of Russian roulette.