There are systematic differences in younger and older adults’ decision making under risk. Previous research has mainly focused on comparing the two age groups in terms of their choice behavior. Very little is currently known about the cognitive processing underlying age differences in risky choice. We analyzed younger and older adults’ information acquisition behavior, measured with a process-tracing software MouselabWEB, with a neurocognitive Markov attention model (He & Bhatia, 2023). According to the model, information acquisition is guided by a mixture of different policies, one of them being an interactive attention policy that transitions between an outcome and its corresponding probability depending on the respective sizes of the attribute values. We applied this model to data from 90 younger and 90 older adults who completed 242 risky choice problems. While both age groups were more likely to transition from a probability to its corresponding outcome when the probability was high, this sensitivity to differences in probabilities was reduced for older adults. Participants with lower sensitivity to differences in probability in the interactive attention process also selected the option with the lower expected value more often and they showed lower probability sensitivity when their choices were modeled with cumulative prospect theory. Our findings suggest that reduced sensitivity to probability differences is a key factor for adult age differences in risky choice and point to a formal account of the neurocognitive processes underlying age differences in attention allocation.