Evidence for magnocellular involvement in the identification of flanked letters
Evidence for magnocellular involvement in the identification of flanked letters
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DOI：
10.1016/s0028-3932(02)00069-6
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发表时间：
2002-01-01
期刊：
影响因子：
2.6
通讯作者：
Kolk, HHJ
中科院分区：
文献类型：
--
作者：
Omtzigt, D;Hendriks, AW;Kolk, HHJ
人们对磁系统在阅读中的作用所知甚少。一个重要的假设是，这个系统参与了注意力的分配。我们推断，单个字母的呈现会自动将注意力吸引到该字母上，而在侧翼字母的情况下，需要额外的注意力分配过程才能发生识别。在三个字母命名实验中，每个实验有24名受试者，正常阅读的成年人在三个可能的中央凹位置看到两个字母（如xxx）和一个字母（如a）。这些字母与背景形成不利于磁强的色彩对比或不利于微弱的亮度对比。对照实验证实，颜色对比比亮度对比产生的大细胞活动更少。颜色对比的呈现导致侧翼字母的命名表现明显低于亮度对比的呈现，尽管事实上两种对比在字母单独呈现时并没有引起命名表现的差异。后一项发现排除了颜色对比不仅产生更少的磁诺，而且比亮度对比产生更少的微粒细胞活动的可能性。因此，可以得出结论，磁诺系统参与了侧面字母的识别。这一结论支持了磁诺系统对注意力分配很重要的假设。此外，它可能为经常发现患有发展性阅读障碍的人在他们的大细胞系统中有损伤提供了解释。(C) 2002 Elsevier Science Ltd.版权所有。
Little is known about the role of the magno system in reading. One important hypothesis is that this system is involved in the allocation of attention. We reasoned that the presentation of a single letter automatically draws attention to this letter, whereas in the case of a flanked letter, an additional process of attention allocation is required for identification to occur. In three letter-naming experiments with 24 subjects each, normally reading adults were presented with flanked (e.g. xax) and with single (e.g. a) letters at three possible (Para)foveal locations. The letters appeared in magno-disadvantageous colour contrast or in parvo-disadvantageous weak luminance contrast with the background. A control experiment verified that colour contrast had generated less magnocellular activity than had luminance contrast. Colour-contrast presentation led to a significantly lower naming performance for flanked letters than did luminance-contrast presentation, despite the fact that the two contrasts did not elicit differences in naming performance when the letters were presented in isolation. This latter finding rules out the possibility that colour contrast had generated not only less magno- but also less parvocellular activity than had luminance contrast. Thus, it can be concluded that the magno system is involved in the identification of flanked letters. This conclusion supports the hypothesis that the magno system is important to the allocation of attention. Further, it may provide an explanation for the frequent finding that people with developmental dyslexia have impairments in their magnocellular system. (C) 2002 Elsevier Science Ltd. All rights reserved.