This article investigates the roles of psychological biases for deviations between subjective survival beliefs
(SSBs) and objective survival probabilities. We model these deviations through age-dependent inverse Sshaped
probability weighting functions. Our estimates suggest that implied measures for cognitive weakness
increase and relative optimism decrease with age. Direct measures of cognitive weakness and optimism share
these trends. Our regression analyses confirm that these factors play strong quantitative roles in the formation
of SSBs. Our main finding is that cognitive weakness instead of optimism becomes with age an increasingly important
contributor to the well-documented overestimation of survival chances in old age.