Volen National Center for Complex Systems, Brandeis University, Waltham, Massachusetts, USA.
Ear Hear. 2018 Jan/Feb;39(1):101-109. doi: 10.1097/AUD.0000000000000469.
The increasing numbers of older adults now receiving cochlear implants raises the question of how the novel signal produced by cochlear implants may interact with cognitive aging in the recognition of words heard spoken within a linguistic context. The objective of this study was to pit the facilitative effects of a constraining linguistic context against a potential age-sensitive negative effect of response competition on effectiveness of word recognition.
Younger (n = 8; mean age = 22.5 years) and older (n = 8; mean age = 67.5 years) adult implant recipients heard 20 target words as the final words in sentences that manipulated the target word's probability of occurrence within the sentence context. Data from published norms were also used to measure response entropy, calculated as the total number of different responses and the probability distribution of the responses suggested by the sentence context. Sentence-final words were presented to participants using a word-onset gating paradigm, in which a target word was presented with increasing amounts of its onset duration in 50 msec increments until the word was correctly identified.
Results showed that for both younger and older adult implant users, the amount of word-onset information needed for correct recognition of sentence-final words was inversely proportional to their likelihood of occurrence within the sentence context, with older adults gaining differential advantage from the contextual constraints offered by a sentence context. On the negative side, older adults' word recognition was differentially hampered by high response entropy, with this effect being driven primarily by the number of competing responses that might also fit the sentence context.
Consistent with previous research with normal-hearing younger and older adults, the present results showed older adult implant users' recognition of spoken words to be highly sensitive to linguistic context. This sensitivity, however, also resulted in a greater degree of interference from other words that might also be activated by the context, with negative effects on ease of word recognition. These results are consistent with an age-related inhibition deficit extending to the domain of semantic constraints on word recognition.
现在越来越多的老年人接受了耳蜗植入，这就提出了一个问题，即耳蜗植入产生的新信号如何与语言环境下听到的单词的认知老化相互作用。本研究的目的是检验语言语境的促进作用是否能对抗反应竞争对单词识别有效性的潜在年龄敏感的负面影响。
年轻（n=8；平均年龄=22.5 岁）和老年（n=8；平均年龄=67.5 岁）成年植入者听到 20 个目标词，这些词是句子的最后一个词，句子语境操纵了目标词在句子中的出现概率。还使用了已发表的规范数据来测量反应熵，反应熵的计算方法是总反应次数和句子语境提示的反应概率分布。使用词起始门控范式向参与者呈现句子结尾词，在该范式中，目标词以其起始持续时间的递增量呈现，每次增加 50 毫秒，直到正确识别出该词。
结果表明，对于年轻和老年成年植入者，正确识别句子结尾词所需的词起始信息的数量与它们在句子语境中的出现概率成反比，老年成年人从句子语境提供的语境约束中获得了不同的优势。另一方面，老年成年人的单词识别受到高反应熵的不同程度的阻碍，这种效应主要是由可能也符合句子语境的竞争反应数量驱动的。
与先前对正常听力的年轻和老年成年人的研究一致，本研究结果表明，老年成年植入者对口语单词的识别高度敏感于语言语境。然而，这种敏感性也导致了更多可能也被语境激活的其他单词的干扰，从而对单词识别的容易程度产生负面影响。这些结果与年龄相关的抑制缺陷扩展到语义约束对单词识别的影响相一致。
