The perceptual use of multisensory information apparently changes with age. Yet it remains unclear whether previously reported age-effects arise from changes in the sensory computations by which information is combined, from reduced sensory precision with age, or changes in the belief that different sensory-motor cues are indeed causally linked. To address this question we analysed how healthy young and older adults integrate audio-visual information within (ventriloquist-effect) and between trials (ventriloquist after-effect) using models of Bayesian causal inference. Despite a reduced precision of sensory representations in the elderly, both groups exhibited comparable ventriloquist biases that were reproduced by largely the same sensory computations. While the after-effect bias was also comparable between groups, modelling showed that this was driven by previous sensory information in younger but by the previous response in older participants. This suggests a transition from a sensory- to a behavior driven influence of past experience on subsequent choices with age, possibly related to the reduced sensory precision or memory capacity with age.