Department of Psychology, Program in Neuroscience, and The Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana-Champaign IL, United States.
Brain Lang. 2010 Dec;115(3):149-61. doi: 10.1016/j.bandl.2010.07.006. Epub 2010 Aug 21.
During sentence comprehension, older adults are less likely than younger adults to predict features of likely upcoming words. A pair of experiments assessed whether such differences would extend to tasks with reduced working memory demands and time pressures. In Experiment 1, event-related brain potentials were measured as younger and older adults read short phrases cuing antonyms or category exemplars, followed three seconds later by targets that were either congruent or incongruent and, for congruent category exemplars, of higher or lower typicality. When processing the less expected low typicality targets, younger - but not older - adults elicited a prefrontal positivity (500-900ms) that has been linked to processing consequences of having predictions disconfirmed. Thus, age-related changes in prediction during comprehension generalize across task circumstances. Analyses of individual differences revealed that older adults with higher category fluency were more likely to show the young-like pattern. Experiment 2 showed that these age-related differences were not due to simple slowing of language production mechanisms, as older adults generated overt responses to the cues as quickly as - and more accurately than - younger adults. However, older adults who were relatively faster to produce category exemplars in Experiment 2 were more likely to have shown predictive processing patterns in Experiment 1. Taken together, the results link prediction during language comprehension to language production mechanisms and suggest that although older adults can produce speeded language output on demand, they are less likely to automatically recruit these mechanisms during comprehension unless top-down circuitry is particularly strong.
在句子理解过程中，老年人比年轻人更不可能预测即将出现的单词的特征。两项实验评估了这些差异是否会扩展到对工作记忆需求和时间压力要求较低的任务中。在实验 1 中，当年轻和年长的成年人阅读提示反义词或类别范例的短语时，测量了事件相关的脑电波，三秒钟后，目标出现的是一致的或不一致的，对于一致的类别范例，目标的典型性更高或更低。当处理不太可能出现的低典型性目标时，年轻的成年人——而不是年长的成年人——诱发了前额正波（500-900ms），这与预测被证实的处理后果有关。因此，理解过程中预测的与年龄相关的变化在任务环境中普遍存在。对个体差异的分析表明，类别流畅度较高的老年人更有可能表现出类似年轻人的模式。实验 2 表明，这些与年龄相关的差异并不是由于语言产生机制的简单减速造成的，因为年长的成年人对提示的反应与年轻人一样快——并且更准确。然而，在实验 2 中相对更快地产生类别范例的年长成年人在实验 1 中更有可能表现出预测性处理模式。总之，这些结果将语言理解过程中的预测与语言产生机制联系起来，并表明，尽管年长的成年人可以按需产生快速的语言输出，但除非自上而下的电路特别强，否则他们在理解过程中不太可能自动招募这些机制。
