Kandhadai Padmapriya, Federmeier Kara D
Department of Psychology, University of Illinois, Urbana-Champaign, Champaign, IL 61820, USA.
Brain Res. 2007 Jun 11;1153:144-57. doi: 10.1016/j.brainres.2007.03.046. Epub 2007 Mar 23.
The coarse coding hypothesis postulates that the cerebral hemispheres differ in their breadth of semantic activation, with the left hemisphere activating a narrow, focused semantic field and the right weakly activating a broader semantic field. In support of coarse coding, studies investigating priming for multiple senses of a lexically ambiguous word have reported a right hemisphere benefit. However, studies of mediated priming have failed to find a right hemisphere advantage for processing distantly linked, unambiguous words. To address this debate, the present study made use of a multiple priming paradigm in which two primes either converged onto the single meaning of an unambiguous, lexically associated target (LION-STRIPES-TIGER) or diverged onto different meanings of an ambiguous target (KIDNEY-PIANO-ORGAN). In two experiments, participants either made lexical decisions to lateralized targets (Experiment 1) or made a semantic relatedness judgment between primes and targets (Experiment 2). In both tasks, for both ambiguous and unambiguous triplets we found equivalent priming strengths and patterns across the two visual fields, counter to the predictions of the coarse coding hypothesis. Priming patterns further suggested that both hemispheres made use of lexical level representations in the lexical decision task and semantic representations in the semantic judgment task.
粗略编码假说假定大脑半球在语义激活广度上存在差异，左半球激活一个狭窄、集中的语义场，而右半球则微弱地激活一个更广泛的语义场。为支持粗略编码，对词汇歧义单词的多种意义启动效应进行研究的报告称存在右半球优势。然而，中介启动效应的研究未能发现右半球在处理远距离关联的明确单词时具有优势。为解决这一争论，本研究采用了一种多重启动范式，其中两个启动词要么汇聚到一个明确的、词汇相关目标的单一意义上（狮子-条纹-老虎），要么发散到一个歧义目标的不同意义上（肾脏-钢琴-器官）。在两个实验中，参与者要么对侧化目标进行词汇判断（实验1），要么对启动词和目标之间的语义相关性进行判断（实验2）。在这两项任务中，对于歧义三元组和明确三元组，我们在两个视野中都发现了等效的启动强度和模式，这与粗略编码假说的预测相反。启动模式进一步表明，两个半球在词汇判断任务中都利用了词汇层面的表征，在语义判断任务中都利用了语义表征。
