Learning to avoid in older age.

The dopamine hypothesis of aging suggests that a monotonic dopaminergic decline accounts for many of the changes found in cognitive aging. The authors tested 44 older adults with a probabilistic selection task sensitive to dopaminergic function and designed to assess relative biases to learn more from positive or negative feedback. Previous studies demonstrated that low levels of dopamine lead to avoidance of those choices that lead to negative outcomes, whereas high levels of dopamine result in an increased sensitivity to positive outcomes. In the current study, age had a significant effect on the bias to avoid negative outcomes: Older seniors showed an enhanced tendency to learn from negative compared with positive consequences of their decisions. Younger seniors failed to show this negative learning bias. Moreover, the enhanced probabilistic integration of negative outcomes in older seniors was accompanied by a reduction in trial-to-trial learning from positive outcomes, thought to rely on working memory. These findings are consistent with models positing multiple neural mechanisms that support probabilistic integration and trial-to-trial behavior, which may be differentially impacted by older age.