Abstract
Metacognition enables adaptive behavior through the self-evaluation of our cognitions. An unresolved question is whether metacognition relies on domain-general or domain-specific mechanisms. The domain-general account proposes that shared prefrontal resources support metacognition across all cognitive functions. This predicts that metacognitive abilities should correlate across cognitive tasks and show uniform age-related decline, as aging would affect this shared system. However, behavioral results show inconsistent cross-domain correlations and age-related decline, often confounded by methodological differences between tasks. The neural oscillations supporting metacognition also remain unclear, though electroencephalography (EEG) studies suggest theta oscillations as a potential mechanism in specific domains. No study has compared both behavioral and oscillatory patterns across domains using matched tasks. We addressed this by recording EEG from younger and older-adults during matched perceptual and visual short-term memory tasks. Despite equivalent task performance, aging selectively impaired metacognition in perception and not memory, revealing behavioral decoupling between domains. This dissociation was mirrored in oscillatory dynamics. Younger adults showed stronger occipital theta-synchronization supporting perceptual metacognition, while older adults engaged compensatory frontal beta-desynchronization. During memory, older adults' metacognition was supported by occipital alpha-desynchronization. These findings reveal the domain-specific oscillatory mechanisms supporting metacognition, each tuned to computational demands of the cognitive domain and age-group.