Impaired Sensory-motor Reconfiguration and Pupil-linked Arousal in Aging

Older adults show reduced pupil-linked arousal during high-probability rule-switch moments in a hierarchical decision task, alongside lower accuracy driven by more incorrect-rule use.

• Why it matters: Aging is linked to declines in brainstem arousal control and cognitive flexibility, but their relationship is unclear. This work tests whether impaired arousal recruitment tracks impaired adaptive behavior.
• What they did: Older and younger adults (60% women) performed a hierarchical decision-making task with hidden rule switches inferred from noisy evidence, while luminance-independent pupil responses indexed arousal dynamics.
• The result: Older adults were less accurate due to more frequent use of the incorrect rule, while perceptual categorization and rule-switch detection did not differ. High switch probability was associated with pupil dilation in both groups, but dilation was reduced in older people, suggesting impaired recruitment limits ongoing reconfiguration for flexibility.

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