Centre for Speech, Language and the Brain, Department of Experimental Psychology, University of Cambridge, Cambridge, United Kingdom.
J Cogn Neurosci. 2011 Dec;23(12):3778-90. doi: 10.1162/jocn_a_00046. Epub 2011 May 12.
Spoken word recognition involves the activation of multiple word candidates on the basis of the initial speech input--the "cohort"--and selection among these competitors. Selection may be driven primarily by bottom-up acoustic-phonetic inputs or it may be modulated by other aspects of lexical representation, such as a word's meaning [Marslen-Wilson, W. D. Functional parallelism in spoken word-recognition. Cognition, 25, 71-102, 1987]. We examined these potential interactions in an fMRI study by presenting participants with words and pseudowords for lexical decision. In a factorial design, we manipulated (a) cohort competition (high/low competitive cohorts which vary the number of competing word candidates) and (b) the word's semantic properties (high/low imageability). A previous behavioral study [Tyler, L. K., Voice, J. K., & Moss, H. E. The interaction of meaning and sound in spoken word recognition. Psychonomic Bulletin & Review, 7, 320-326, 2000] showed that imageability facilitated word recognition but only for words in high competition cohorts. Here we found greater activity in the left inferior frontal gyrus (BA 45, 47) and the right inferior frontal gyrus (BA 47) with increased cohort competition, an imageability effect in the left posterior middle temporal gyrus/angular gyrus (BA 39), and a significant interaction between imageability and cohort competition in the left posterior superior temporal gyrus/middle temporal gyrus (BA 21, 22). In words with high competition cohorts, high imageability words generated stronger activity than low imageability words, indicating a facilitatory role of imageability in a highly competitive cohort context. For words in low competition cohorts, there was no effect of imageability. These results support the behavioral data in showing that selection processes do not rely solely on bottom-up acoustic-phonetic cues but rather that the semantic properties of candidate words facilitate discrimination between competitors.
口语识别涉及基于初始语音输入（“语料库”）激活多个单词候选词，并在这些竞争者中进行选择。选择可能主要由自上而下的声学语音输入驱动，也可能受到词汇表示的其他方面的调制，例如单词的含义[Marslen-Wilson，WD。口语识别中的功能并行。认知，25，71-102，1987]。我们通过向参与者呈现单词和伪词进行词汇决策，在 fMRI 研究中检查了这些潜在的相互作用。在一个因子设计中，我们操纵了（a）语料库竞争（高/低竞争语料库，竞争单词候选词的数量不同）和（b）单词的语义属性（高/低可想象性）。以前的行为研究[Tyler，LK，Voice，JK，和 Moss，HE。声音与声音在口语识别中的相互作用。心理与评论，7，320-326，2000]表明，可想象性有助于单词识别，但仅适用于高竞争语料库中的单词。在这里，我们发现随着语料库竞争的增加，左额下回（BA 45、47）和右额下回（BA 47）的活动增加，左后颞中回/角回（BA 39）的可想象性效应，以及左后颞上回/颞中回（BA 21、22）中图像和语料库竞争之间的显著交互作用。在具有高竞争语料库的单词中，高可想象性单词比低可想象性单词产生更强的活动，这表明在高度竞争的语料库环境中，可想象性具有促进作用。对于低竞争语料库中的单词，没有可想象性的影响。这些结果支持行为数据表明，选择过程不仅依赖于自下而上的声学语音线索，而且候选词的语义属性有助于区分竞争者。
