Multistep inference across the human lifespan can be improved with individualized memory interventions

OBJECTIVES: Effective goal-directed decision making relies on memory and planning-processes that are known to decline with age. We tested the hypothesis that these declines stem from a common mechanism by focusing on mnemonic discrimination, a measure of memory precision that shows unique vulnerability to age-related decline. METHODS: We used a latent learning task that measures the ability to learn and make judgments about associations among interconnected stimuli, assessing performance across the adult life span. This task allows us to measure multistep inference judgments that reflect how individuals organize relational structure, previously shown to capture the internal model-construction processes that support model-based planning. In Experiment 1, we examined relationships between judgment performance and memory precision. In Experiment 2, we tested whether a "blocked" learning schedule designed to reduce memory interference by separating overlapping objects could improve performance for individuals with weaker memory abilities. RESULTS: Across the life span, both younger and older adults showed evidence of successful latent learning and inference, but variability in judgment performance was explained by mnemonic discrimination ability. In Experiment 2, mnemonic discrimination interacted with training condition: intermixed training benefited those with high memory precision, whereas blocked training benefited those with low memory precision. We also implemented artificial neural network simulations, which reproduced these qualitative patterns. DISCUSSION: These findings suggest that age-related declines in complex judgments stem from declines in mnemonic discrimination and demonstrate that individualized, memory-based training interventions can improve learning and reasoning processes that support goal-directed planning, offering a promising approach to preserving decision-making abilities across the life span.