tl;dr: Brain scans of adults aged 18-74 during a face-object/scene pairing task found that older adults' memory errors weren't just forgetting—they showed "category-level misbinding," confusing items across entirely different categories (e.g., linking a face to a scene instead of an object). In younger adults, hippocampal activity overlap between learning and recall predicted accuracy; in older adults, that same overlap predicted these cross-category mix-ups, suggesting aging brains replay memories too broadly. Hippocampal shrinkage and attention differences didn't fully explain the effect.