Grindrod Christopher M, Baum Shari R
School of Communication Sciences and Disorders and the Centre for Research on Language, Mind and Brain, McGill University, 1266 Pine Avenue West, Montreal, Que, Canada H3G 1A8.
Brain Lang. 2003 Jun;85(3):503-23. doi: 10.1016/s0093-934x(03)00072-5.
Using a cross-modal semantic priming paradigm, the present study investigated the ability of left-hemisphere-damaged (LHD) nonfluent aphasic, right-hemisphere-damaged (RHD) and non-brain-damaged (NBD) control subjects to use local sentence context information to resolve lexically ambiguous words. Critical sentences were manipulated such that they were either unbiased, or biased toward one of two meanings of sentence-final equibiased ambiguous words. Sentence primes were presented auditorily, followed after a short (0 ms) or long (750 ms) interstimulus interval (ISI) by the presentation of a first- or second-meaning related visual target, on which subjects made a lexical decision. At the short ISI, neither patient group appeared to be influenced by context, in sharp contrast to the performance of the NBD control subjects. LHD nonfluent aphasic subjects activated both meanings of ambiguous words regardless of context, whereas RHD subjects activated only the first meaning in unbiased and second-meaning biased contexts. At the long ISI, LHD nonfluent aphasic subjects failed to show evidence of activation of either meaning, while RHD individuals activated first meanings in unbiased contexts and contextually appropriate meanings in second-meaning biased contexts. These findings suggest that both left (LH) and right hemisphere (RH) damage lead to deficits in using local contextual information to complete the process of ambiguity resolution. LH damage seems to spare initial access to word meanings, but initially impairs the ability to use context and results in a faster than normal decay of lexical activation. RH damage appears to initially disrupt access to context, resulting in an over-reliance on frequency in the activation of ambiguous word meanings.
本研究采用跨模态语义启动范式，调查了左半球损伤（LHD）的非流畅性失语症患者、右半球损伤（RHD）患者和非脑损伤（NBD）对照受试者利用局部句子语境信息来解决词汇歧义的能力。对关键句子进行了处理，使其要么无偏向性，要么偏向句子末尾等偏向性歧义单词的两种含义之一。句子启动项通过听觉呈现，在短（0毫秒）或长（750毫秒）的刺激间隔（ISI）后，呈现与第一种或第二种含义相关的视觉目标，受试者对该目标进行词汇判断。在短ISI时，与NBD对照受试者的表现形成鲜明对比的是，两个患者组似乎都未受语境影响。LHD非流畅性失语症受试者无论语境如何都会激活歧义单词的两种含义，而RHD受试者在无偏向性和偏向第二种含义的语境中仅激活第一种含义。在长ISI时，LHD非流畅性失语症受试者未表现出激活任何一种含义的证据，而RHD个体在无偏向性语境中激活第一种含义，在偏向第二种含义的语境中激活符合语境的含义。这些发现表明，左半球（LH）和右半球（RH）损伤都会导致在利用局部语境信息完成歧义解决过程中出现缺陷。LH损伤似乎不影响对单词含义的初始通达，但最初会损害利用语境的能力，并导致词汇激活的衰减速度快于正常情况。RH损伤似乎最初会干扰对语境的通达，导致在激活歧义单词含义时过度依赖词频。
