Podrouzek K W, Modigliani V, Di Lollo V
Simon Fraser University, Burnaby, British Columbia, Canada.
Perception. 1992;21(6):705-16. doi: 10.1068/p210705.
The term compound letter refers to a large (global) letter made up of small (local) letters. Reaction time to identify local letters is longer when local and global letters are different than when they are the same (the global dominance effect). The possible contribution of lateral masking to this effect was investigated. Lateral masking denotes reduced probability of identifying a stimulus when it is closely surrounded by other stimuli (as is the case for the local items in a compound stimulus). Three experiments were conducted in which the dependent measure was percentage of correct responses, rather than reaction time. In experiment 1 compound letters were used; accuracy of performance yielded evidence of global dominance such as obtained with reaction time measures. In experiments 2 and 3 the strength of lateral masking in geometrical forms was varied by varying the density of their component items. In agreement with earlier suggestions based on indirect evidence, the results directly implicated lateral masking as an important determinant of global dominance. However, lateral masking could not account fully for the experimental outcome. Factors beyond lateral masking, such as global precedence in the processing sequence or inhibitory interactions among low and high spatial-frequency components of the compound images are required in order to provide a comprehensive account of global dominance effects.
复合字母一词指的是由小（局部）字母组成的大（整体）字母。当局部字母和整体字母不同时，识别局部字母的反应时比它们相同时更长（整体优势效应）。研究了侧向掩蔽对这种效应的可能贡献。侧向掩蔽是指当一个刺激被其他刺激紧密包围时（复合刺激中的局部项目就是这种情况），识别该刺激的概率降低。进行了三个实验，其中因变量是正确反应的百分比，而不是反应时。在实验1中使用了复合字母；表现的准确性产生了整体优势的证据，就像用反应时测量所得到的那样。在实验2和3中，通过改变几何图形组成部分的密度来改变侧向掩蔽的强度。与基于间接证据的早期观点一致，结果直接表明侧向掩蔽是整体优势的一个重要决定因素。然而，侧向掩蔽不能完全解释实验结果。为了全面解释整体优势效应，需要考虑侧向掩蔽之外的因素，例如处理序列中的整体优先性或复合图像的低空间频率和高空间频率成分之间的抑制性相互作用。
