Older compared to younger adults show greater amygdala activity to positive emotions, and are more likely to interpret emotionally ambiguous stimuli (e.g., surprised faces) as positive. While some evidence suggests this positivity effect results from a top-down, effortful mechanism, others suggest it may emerge as the default or initial response. The amygdala is a key node in rapid, bottom-up processing and patterns of amygdala activity over time (e.g., habituation) can shed light on the mechanisms underlying the positivity effect. Younger and older adults passively viewed neutral and surprised faces in an MRI. Only in older adults, amygdala habituation was associated with the tendency to interpret surprised faces as positive or negative (valence bias), where a more positive bias was associated with greater habituation. Interestingly, although a positive bias in younger adults was associated with slower responses, consistent with an initial negativity hypothesis in younger adults, older adults showed faster categorizations of positivity. Together, we propose that there may be a switch to a primacy of positivity in aging.

与年轻人相比，老年人对积极情绪表现出更大的杏仁核活动，并且更有可能将情绪模糊的刺激（例如，惊讶的面孔）解释为积极的。虽然一些证据表明这种积极效应是由自上而下的、努力的机制产​​生的，但另一些证据表明它可能作为默认或初始反应出现。杏仁核是快速、自下而上处理的关键节点，随着时间的推移（例如，习惯化）的杏仁核活动模式可以揭示积极效应背后的机制。年轻人和老年人在核磁共振成像中被动地观察中性和惊讶的面孔。只有在老年人中，杏仁核习惯与将惊讶的面孔解释为正面或负面的倾向有关（效价偏差），其中更积极的偏见与更大的习惯​​相关。有趣的是，尽管年轻人的积极偏见与较慢的反应有关，这与年轻人最初的消极假设一致，但老年人表现出更快的积极分类。我们一起提出，老龄化可能会转向积极性的首要地位。